fyxmll ^nivmii^ f ;ilratg BOUGHT WITH THE INCOME •FROM THE SAGE ENDOWMENT FUND THE GIFT OF Henrg M. Sage 1891 ...A-.N.^fH^ - . ..M/JX/Jf^... RETURN TO ALBERT R. MANN LIBRARY ITHACA, N. Y. Cornell University Library TX 555.M68 Flesh foods, with methods for their chem 3 1924 003 547 563 Cornell University Library The original of tliis book is in tlie Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924003547563 FLESH FOODS A PEACTICAL HAND-BOOK SELECT WORKS for ANALYSTS, ENGINEERS, & OTHERS DAIRY CHEMISTRY FOR DAIRY MANAGERS, CHEMISTS, and Analysts. A Practical Handbook for Dairy Chemists and others having control o Dairies. With Tables and Illustrations. By H. DROOP RICHMOND, T.C.S., Chemist to tlie Aylesbury Dairy Company. §4.50. " The BEST OONTKIBUTION On the subject that has yet appeared."— ioncei. THE PRINCIPLES AND PRACTICE OF BREWING. A Text- Book for the use of Students and Practical Men. By WALUE J. STKBB, M.D., D.P.H., F.I.C., Editor of the Analyst. With Plates and numerous Illustrations. $6.00. " A BETTER aoiDH could hardly be found."— ComjiJi/ Brewers' Gazette. TECHNICAL MYCOLOGY. A Practical Handbook on Fermentation for Brewers, Distillers, Analysts, Technical and Agricultural Chemists. By Dr Franz Lafar, Professor of Fermentation-Physiology and Bacteriology in the Technical High School, Vienna. Vol, I., Complete IN itself. With numerous Illustrations. Price S4.00. "The chapters teem with interbstinb matter from beginning to end."— fAe Lancet. OILS, FATS, WAXES, and the Manufacture therefrom of Soaps, Candles, and other Products. By C. R. ALDER WRIGHT, D.Sc, F.E.S. With 144 lUustrations. Handsome cloth. S6.75. " Will be found absolutely indispensable by every chemist."— rAe Analyst. LUBRICANTS AND LUBRICATION. The Theory and Practice of Lubrication, and the Nature, Properties, and Testing of Lubricants. 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K 02 H Pw»"«ire^?waw5 a. 02 H O ■0^?ff?^l?^0iW^^P?CIiff^|fg^^!Bg()(!f^^ ea eq H f5W*'s-i^iS:j5^'^ie5?evs FLESH FOODS WITH METHODS FOR THEIR CHEMICAL, MICROSCOPICAL, AND BACTERIOLOGICAL EXAMINATION A Practical Hand-Book for Medical Men, Analysts, Inspectors, and others , ../■ BY V C. AINSWOETH :^ITCHELL, B.A. (Oxon.), F.I.C, F.C.S. MEMBKK OF OODNOIL, SOCIETr OF PUBLIC ANALYSIS WITH ILLUSTEATIONS AND A COLOtTRED PLATE LONDON CHAELES GEIFFIN & COMPANY, LIMITED Philadblphia : J. B. LIPPINCOTT COMPANY 1900 [All Mights Reserved.'] TO OTTO HEHNER, Esq., PAST-PRESIDENT OF THE SOCIETY OF PUBLIC ANAITSTS, VICE-PKESIDBNT OF THE INSTITUTE OF OHEMISTET, ae a matft of IRegarD an5 Esteem. PREFACE. The word 'flesh,' like so many other words in the English language, has come to have a very extended application, and although in its strictest sense it is applied to the muscular tissue only, yet it is often used to connote the combined mus- cular and connective tissue (including fat and bone), or even the whole of the interior organs and tissues of an animal. It is with flesh in the sense of muscular fibre that this book chiefly deals, although the connective tissue and blood are touched upon as being intimately associated with the muscle. It has been the author's endeavour to collect and summarise in a convenient form, records of investigations which are, for the most part, scattered throughout English and foreign scientific books and periodicals, and to select such methods as appeared most suitable for the examination of meat and its preparations. In describing these methods an elementary knowledge of analytical chemistry and bacteriology on the part of the reader has been assumed, so as to save the space which would have been required for details which may be found in any general text-book. The author gratefully acknowledges the valuable assistance given him by many friends in the preparation of this book, and especially by Mr. Otto Hehner, and by Dr. Sykes, editor of the Analyst, to whom he is also indebted for the loan of numerous preparations of the parasites of flesh. VUl PREFACE. He would also express his best thanks to Mrs. E. Mitchell and Mr. R. M. Prideaux, F.I.C, for their kindness in drawing many of the illustrations ; to Dr. Kdnig for permission to make use of the numerous tables published in his classical work, CJiemie der menschliehen Nahrungs- und Genussmittel ; and to Dr. H. Schjerning for the communication of the results of unpublished work. C. A. M. 57 Chanoeey Lane, London, W.C, Mil, I 1900. CONTENTS. CHAPTEE I. STRUCTITRE AND CHEMICAL COMPOSITION OF MUSCULAR FIBRE. Structure of Muscle. — Non-striated Muscle — Striated Muscle — Pale and Red Muscles — Muscle Plasma. Proteid ConstituentB. — The Sarcolemma — Proteids of Muscle Plasma — Nucleins— Phospho-Carnic Acid — Enzymes — Colouring Matters — Stroma Substance. Nitrogenous Non-proteid Con- stituents. — Meat Extractives — Neurinic Leucomaines — Kreatinic Bases — Xanthic Bases — Leucomaines of the Fatty Acid Series — Amido Acids, Non-nitrogenous Organic Constituents. — Reaction of Muscle — Free Acids — Glycogen — Fat— Glucose— Inosite—Scyllite. Inorganic Con- stituents. — Mineral Matter— Water — Gases. Summary of the Com- position of Muscular Fibre, .... pp. 1-22 CHAPTER II. STRUCTURE AND COMPOSITION OF CONNECTIVE TISSUE AND BLOOD. Connective Tissue.— White Fibres— Elastic Fibres. Adipose Tissue.— Dis- tribution of Fat in the 'Body — Composition of Animal Fat. Cartilage. — Structure — Composition. Osseous Tissue. — Structure — Composition —Table of Mineral Constituents of Bone. The Blood.— Quantity in the Body — General Characteristics — Conditions affecting its Coagulation — The Red Corpuscles — Oxyhremoglobin Crystals — Hsemin Crystals — Spectra of Haemoglobin and its Compounds — The White Corpuscles — The Blood Plasma — Proteids of the Plasma — Inorganic Constituents of the Plasma — Gases in Blood— Ultimate Composition of Blood — Proximate Composition of Blood — Identification of Blood in Stains, etc.— The Blood of Invertebrate Animals — Hamolymph, . . pp. 23-45 CONTENTS. CHAPTEE III. THE FLESH OP DIFFERENT ANIMALS. Flesh of Domestic Animals. — Beef — Veal— Mutton — Composition of the Flesh and Fat — ' Braxy ' Mutton — Pork — Composition of Pig's Fat — Horse Flesh— Horse Fat. The Flesh of Wild Animals and Birds.— General Characteristics— Bear's Flesh — Composition of the Fat of Wild Animals and Birds — 'Ripening' and 'Heating' of Game. The Flesh of Vertebrate Fish.- General Characteristics — The Fat of Fish — Con- stants of Certain Fish OUs. The Flesh of Invertebrate Animals. — Composition of Representative Examples — Green Oysters, . pp. 46-69 CHAPTER IV. THE EXAMINATION OF FLESH. Colour. — Abnormal Colorations — Artificial Coloration. Unsound Flesh. — Chemical Tests — Eber's Hydrogen Sulphide Test — The Reaction towards Litmus — Eber's Teat for Putrefaction. Treatment of Meat with Anti- septics. Blown Meat. Consistency of Flesh. — Determination of the Degree of Toughness. Odour of Flesh. Analytical Methods. — Deter- mination of Water — Ash — Sulphur — Chlorine — Soluble Extract and Muscular Fibre — Phospho-Carnic Acid — Amide Nitrogen — Fat — Digesti- bility of Different Kinds of Flesh— Calculation of the Food A''alue — Scheme for the Examination of Fresh Meat, . . pp. 70-90 CHAPTER V. METHODS OF EXAMINING ANIMAL FAT. Crystallisation — Specific Gravity — Melting and Solidifying Points — Iodine Value — Saponification Value — Hehner Value — Reichert Value — Acetyl Value — Acid Value^Separation of Liquid and Solid Fatty Acids- Determination of Stearic Acid — Oleic Acid — Linolic Acid — Linolenic Acid, . . . ' . . . .pp. 91-101 CHAPTER VI. THE PRESERVATION OF FLESH AND THE COMPOSITION AND EXAMINATION OF PRESERVED FLESH PRODUCTS. The Decomposition of Flesh. Preservation by Cold. — Alterations in Frozen Flesh — Detection of Frozen Meat. Preservation by Drying. — Pemmican —Charque— Flesh Powder. Preservation by Salting.— Methods of Salt- CONTENTS. XI ing — Addition of Nitre — Influence of Salting on the Flesh — Caviar. Freseiration by Smoking. — Methods of Smoking — Action of Smoke on Bacteria — Influence on the Flesh — Composition of Bacon. Heat Steri- lisation and Exclusion of Air. — Canned Meats — Sardines — Methods of Examining Canned Meats — Metallic Contamination — Potted Meats. Preservation by Antiseptics.— Boric Acid — Sulphites — Salicylic Acid- Formaldehyde, , . . . . .pp. 102-124 CHAPTER VII. THE COMPOSITION AND ANALYSIS OP SAUSAGES. German Sausages — English Sausages— French Sausages — Water in Sausages — ^The Specific Gravity — Determination of Flour or Starch— Acidity — Acid Value of the Fat — Determination of Gristle — Detection of Horse- flesh — Artificial Coloration — Action of Certain Dyes on Flesh Proteids — Action of Nitre on Natural Colouring Matters in Flesh — Methods of Extracting Artificial Colours, . . . .pp. 125-146 CHAPTER VIII. THE PEOTEIDS OP FLESH. Definition and Classification of Proteids. — Composition of Representative Proteids — Albuminous Substances — Compound Albuminous Substances — Albuminoid Substances — Albumoses — Peptones — Combinations of Pro- teids with Hydrochloric Acid — Colour Reactions of Proteids — Heat Coagulation — Optical Rotation. Precipitation of Proteids. — By Alcohol — By ' Salting out ' — By Metallic Salts — Relation to the Periodic Law — Precipitation by Halogens — Sclijerning's Method. Action of Formalde- hyde on Proteids. Decomposition of Proteids. — By Sulphuric Acid — By Superheated Steam — By Proteolytic Enzymes — By Bacteria, pp. 147-185 CHAPTER IX. MEAT EXTRACTS AND FLESH PEPTONES. Manufacture of Meat Extracts. — Physiological Value. Fluid Beef and Pep- tones. — Prepared by the action of Superheated Steam — By Pepsin — By Trypsin — By Papayotin — Physiological Value of Fluid Beef and Pep- tones. Analysis and Composition of Meat Extracts and Commercial Peptones. — Stutzer's Method — Use of Formaldehyde in the Analysis of Peptones — Analyses by Alcohol Precipitation — Schjerning's Method, pp. 186-206 XU CONTENTS. CHAPTER X. THE COOKING OF FLESH. Advantages of Cooking — Amount of Loss — Composition of Cooked Meat — Composition of Cooked Fish— Effect of Cooking on Animal Parasites — Tliermal Death Points of Bacteria — Action of Heat on Bacterial Toxines — Temperatures reached in the ordinary Processes of Cooking — Public Sterilisation of Infected Flesh in Germany, . . pp. 207-215 CHAPTER XI. POISONOUS FLESH. Flesh rendered Poisonous by the Food of the Animal — Poisons elaborated in the Cells of the Living Animal — Leucomaines also known as Ptomaines — Poisonous Fish — Poisons produced by Bacteria in the Living Animal — Mussel Poisoning — Poisons produced by the Action of Bacteria on the Dead Flesh — Summary of the Principal Ptomaines — Symptoms of Ptomaine Poisoning — Botulism or Sausage Poisoning, . pp. 216-226 CHAPTER XII. THE ANIMAL PARASITES OF FLESH. Classification ofEntozoa. Sporozoa. — Miesuher's Tubes — Coooidia. TseuiadsB. — Cystic Tapeworms — Cysticerci in Beef and Pork — Ccenurus Cerebralis — Tfenia Echinococcus. Bothriooephalidse. — B. Latus — Temperatures at which Cysticerci perish — Influence of Putrefaction on Cysticerci — Examination of Flesh for Cysticerci. Trematoda or Liver Flukes. The Trichina. — Life History — Number of Trichina in Infected Flesh — Detection of TrichinEe — Parasites which might be mistaken for Trichinse — The Temperature at which Trichinte perish — The Destruction of TrichinEe in Flesh — Effect of Salting and Smoking — Occurrence of Trichinje and Trichinosis, ..... pp. 227-264 CHAPTER XIII. THE BACTERIOLOGICAL EXAMINATION OF FLESH. Bacteriological Methods — Embedding and Staining — Determination of the Number and Species of Micro-organisms — Bacteria of Normal Flesh — Chromogenic Bacteria — Phosphorescent Flesh — Bacteria of Putrefaction and their Products — The Bacillus of Sausage Poisoning. Pathogenic CONTENTS. xiii Bacteria. — Pyismia — Septiciemia — Swine Fever — Hog Cholera — Fowl Cholera — Swine Erysipelas — Malignan t CEderna — Tetanus — Rabies — Glanders — Anthrax — Quarter Evil — Foot-and-Mouth Disease — Tuber- culosis — Actinomycosis — Bothriomyoosis — The Muscle Ray-Fungus — Pathogenic Bacteria in Shell-fish, . . . • PP. 265-297 CHAPTER XIV. THE EXTRACTION AND SEPARATION OF PTOMAINES. Brieger's Method of Extraction — Pouchet's Method — The Stas-Gautier Method — DragendorfPs Method — Systematic Description of Ptomaines. Monamines. Diamines. — Putrescine — Cadaverine — Neuridine — Saprine. Triamines and Tetramines of the Fatty Acid Series. — Guanidines. Aromatic Ptomaines not containing Oxygen. Monamines. — Pyridine — Corindine. Aromatic Diamines and Triamines. — Morrhuine. Aromatic Tetramines.-^Aselline — Scombrine. Ptomaines containing Oxygen or Sulphur. — Neurine — Choline — Muscarine — Betaine — Mydatoxine — Gadinene — Mydaleine — Tyrosamines — Mydine — Tirotoxine — Amido Acids — Carbopyridic Acids, . ■ , • PP- 298-322 Index, ...... pp. 323-336 LIST OF ILLUSTRATIONS. Fia. PAGE 1. Isolated Smooth Muscle, ..... .2 2. Strands of Smooth Muscle from Bladder of Frog, ... 2 3. Cardiac Muscular Fibre, . . . . _ . .2 i. Striped Muscle of Frog, ...... 3 5. Striped Muscle of Calf, Teased, ... .3 6. Muscular Fibre of Great Adductor of Rabbit, . . 3 7. Fat Cells from Babbit, . . . . . .24 8. Fat Cells showing Nucleus, .... .24 9. Transverse Section of Shaft of Human Femur, . . .30 10. Cancellated Bone, ....... 30 11. Human Red and White Blood-Corpuscles, . . . .34 12. Haemoglobin Crj'stals from Blood, ..... 35 13. Fleischl's Hsemometer, ...... 36 14. Hsemin Crystals, ... ... 38 15. Spectra of Hsemoglobin and its Compounds, . . .39 16. White Corpuscles under different Reagents, . . .40 17. Apparatus for the Determination of Stearic Acid, . . .100 18. Apparatus for collecting Gases from Cans, .... 115 18a. Halliburton's Apparatus for separating Proteids by Heat Coagulation, 162 19. Preparation of Muscle containing Miescher's Tubes, . . 228 20. A Single Miescher's Tube, ...... 228 21. Coccidia in the Liver of a Rabbit, ..... 229 22. Tosnia saginata (Natural Size), .... 232 23. Head of Cystioerci of T. saginata, ..... 233 24. ' Measles ' in Beef, ....... 233 25. Section of Free Proglottis of T. solium, .... 234 26. Portion of Section of T. solnim, ..... 235 27. Section of Proglottis of T. solium, with Sexual Organs, . . 235 28. ' Measles ' in Pork, . . . . . . .236 29. Swine Cysticercus, ....... 237 30. Egg of T. solium, ....... 237 31. Head, etc., of T. solium and T. saginata, .... 237 32. Cysticerci of T. solium, ...... 238 LIST OF ILLUSTRATIONS. XV PIO. 33. Cystioercus of T. solium, 34. Head of Cystkcrcus pisiformia, 35. CcBiiuriis cerebralis, . 36. Cysticercus fasciolaris, 37. Echinocoocus Bladder, 38. T. ediinococcus, 39. Head of B. latus, . 40. Ovum of B. latits, . 41. Ciliated Embryo of B. latus, 42. Higher Larva of B. latios, . 43. Higher Larva of 5. fates, encapsuled, 44. Common Liver Fluke, 45. Immature female Trichina, . 46. Encysted Trichinse in Human Flesh, 47. Calcified Muscle Trichinx, . 48. Calcified Muscle Trichinw, . 49. Dead, Calcified Trichinse, . 50. Dead, Calcified and Disintegrated Trichinse. 51. Kschoeder's Compressor, 52. Muscle Ray-Fungus, 53. Calcareous Deposit in Muscle, 64. Crystalline Deposit in Smoked Ham, 55. Muscle Distomum, . 56. Bacteria (after Baumgarten), 57. Ranvier's Microtome, 58. Swift's Freezing Microtome, PAGE 238 240 241 241 243 243 245 245 245 246 246 251 253 255 255 256 256 256 258 259 260 261 261 266 267 268 FLESH FOODS. CHAPTER I. STRUCTURE AND CHEMICAL COMPOSITION OF MUSCULAR TISSUE. STEUCTUEE OF MUSCLE. CLASSIFICATION OF MUSCULAR FIBRES. Flesh, in its primary sense of musaular contractile tissue, con- sists of numbers of fibres lying side by side, and united by means of connective tissue carrying the nerves and blood-vessels. These muscular fibres may be classified into three groups in accordance with their appearance under the microscope. 1. Unstriated involuntary muscle of the alimentary canal, blood-vessels, intestines, bladder, etc. 2. Striated involuntary muscles of the heart. 3. Striated voluntary muscles. 1. Non-Striated Muscle. — The unstriated or smooth muscular fibres, which are not under the control of the will, are composed of a number of small fibre cells, which are usually spindle-shaped and contain an elongated nucleus, the ends of which are surrounded by granular protoplasm. Although usually described as unstriped muscle, a longitudinal striation may frequently be observed in the fibres, especially after they have been treated with reagents. 2. Cardiac Muscle. — This occupies an intermediate position, as regards structure, between the non-striated and striated muscle. It consists of elongated and branched cells, each of which contains a nucleus, and is marked by faint longitudinal and rough trans- verse striations. 3. Voluntary Striated Muscle. — The transversely striped muscular fibres, which, from the fact that they compose the A FLESH FOODS. muscular tissue under the control of the will, are often de- scribed as Yoluntary muscles, consist of long contractile fibres about -i^inch in diameter, and as much as an inch or more in length. ^■s :* ,^vj- / . i,- '.IV--. ■ ■ .■'It / ■* •* :/•• r Fig. 1. — Isolated smooth muscle. X 300. (Stirling.) Fig. 2. — Strands of smooth muscle from Bladder of Frog. Each fibre is surrounded by an elastic envelope or sarcolemma, which is a structureless proteid body. On breaking a fibre in two, the ends of the sarcolemma may often be left attached to the two Fig. 3. — Cardiac muscular fibre. A, muscular fibres from the heart of a mammal, and 0, from a frog ; B, transverse section of the cardiac fibres ; b, connective tissue corpuscles ; c, capillaries. (Landois and Stirling. ) fragments. The fibres, with their surrounding sarcolemma, are bound together by a variety of connective tissue, in which lies a deposit of fat. From the interior of the fibre a viscous liquid CLASSIFICATION OF MUSCULAR FIBRES. 3 which readily congeals to a soft jelly can be expressed. This is known as muscle plasma. Fig. 4. — Striped muscle of Frog. A, sarcolemma raised ; B and C, ruptured fibres ; D, fibre treated with acetic acid ; E, muscle discs. {Stirling. ) Fig. 5. — Part of striped muscle of Calf, teased, showing isolated bundles of fibrils. x 200. {Stirling.) Fig. 6. — Muscular fibre of great adductor of Rabbit, living and ejrtended. a, dim disc ; b, light disc ; c, intermediate or Dobie's line ; n, nucleus seen in profile. Examined in its own juice, x 300. {Stirling.) Voluntary muscle shows but little vertical striation, but has characteristic transverse markings composed of alternating dark 4 FLESH FOODS. and bright lines. When examined under higher powers of the microscope, the lighter stripe shows a further division, a thin black line, known as Krause^s membrane, making its appearance. In the darker stripes a region less dark than the rest may also be observed. This is known as Hensen's disc. Striated muscle, after being steeped in alcohol or chromic acid, can be resolved into fibrillx, in each of which alternately light and dark transverse markings are visible. Horizontal cleavage can be brought about by macerating the fibres in dilute hydrochloric acid, which creates a tendency to split across through the bright bands, into a number of discs termed discs of Bowman. The numberless small particles which would be produced by a simul- taneous vertical and horizontal cleavage were called by Bowman * sarcous elements — a term which is now used in a different sense. Sub-division of Voluntary Muscle. — The voluntary muscles of some animals show distinct differences in appearance, some being pale and others red. In the pale muscles, an example of which is seen in the breast muscles of a hen, the striations are well marked, and the longitudinal markings very faint; in the red muscles the vertical striations are much more plainly visible. The red muscles contract more slowly than the pale muscles, the fibres are thinner, and they contain more sarooplasm. Double Refraction of Muscle. — The property of double refraction is a characteristic of muscular fibre, and is readily demonstrated by means of the polariscope. It is especially marked in the case of striated fibre, though also clearly discernible in the smooth variety. Muscle Plasma. — When dead muscular fibre is examined, all the contents of the sarcolemma are solid ; but by rapidly freezing living muscular fibre and applying pressure, it is possible to express a viscous liquid which readily congeals to a soft jelly. This is known as muscle plasma, and it is the coagulation of this plasma which causes the rigidity of muscular tissue, or rigor mortis, which rapidly sets in after death. The coagulation is retarded by cold, but only in the case of cold-blooded animals is it possible to thus delay it sufficiently to enable the plasma to be collected. According to Kiihne the contents of the sarcolemma consist of sarcous elements suspended in this liquid, and the changes which these bodies undergo in their form cause the con- traction of the muscle. * Phil. Trans. Eoy. Soc, 1840, p. 457. PEOTEID CONSTITUENTS OF MUSCLE. CHEMICAL COMPOSITION OF MUSCLE : L ORGANIC COMPOUNDS. A.— PEOTEID CONSTITUENTS. The Sarcolemma. — This is composed of a proteid substance which is somewhat related to that of elastic tissue, from which, however, it differs in being slowly dissolved by acids and alkalies, and in being more readily acted upon by peptic and pancreatic enzymes. Muscle Plasma. — Preparation. — Kiihne's method of preparing this is to free the muscular tissue of a frog from blood by injection of a solution of salt (0"5 per cent.) into the aorta, and to treat the fibre cut into small fragments, at 0° C, with more of the salt solution to eliminate the lymph. The fragments are then frozen by exposure to a temperature of - 7° C, cut into slices with chilled knives, pounded in a cold mortar, and pressed in linen at the ordinary temperature. The expressed liquid, which has a tem- perature of about 0° C, is filtered through paper moistened with ice-cold salt solution. Proteids of Muscle Plasma. — Neumeister * gives a description of these, of which the following is a summary : — Myogen fibrin. — On warming muscle-plasma to about 40° C. coagulation takes place — a proteid substance, named myogen fibrin by Ftirth,! being deposited. The amount of this varies in different animals, a larger quantity being obtained from frogs' muscle, for instance, than from that of mammals. Myosin. — On dialysing the plasma, from which the myogen fibrin has been removed, for twelve to twenty-four hours, in running water, and subsequently in distilled water, a voluminous precipitate is obtained. This proteid, termed myosin by Fiirth, can also be precipitated by adding ammonium sulphate until the solution contains 23 per cent. It is of a globulin character. Myosin fibrin. — When a neutral aqueous solution of myosin, con- taining salt, is allowed to stand, it gradually becomes turbid and deposits a flocculent precipitate — myosin fibrin. This is insoluble in neutral liquids, and is regarded as an insoluble modification of myosin. It is completely precipitated from neutral solutions of myosin at 50° C. Myogen. — Myosin composes only about 20 per cent, of the proteids of plasma (rabbits'), the remaining 80 per cent, consisting of a proteid not precipitated by dialysis — myogen. It can be * Phys. Chem., p. 401. fArch. Exper. Path. M. Fharm., IS 95, 36, p. 231, etc. 6 FLESH FOODS. isolated by complete saturation of the muscle plasma with ammonium sulphate after the myosin has been removed by partial saturation. It is not a globulin. On adding acetic acid or mineral acids to solutions of myogen, and then neutralizing, syntonin is precipitated. Soluble myogen fibrin appears to be an intermediate stage in the formation of myogen fibrin. Neumeister gives the following genetic scheme of the pro- duction of muscle fibrins from the plasma, and considers that some such change probably takes place in the alteration which occurs in muscle after death : — Myosin. Myogen. I I Myosin fibrin. Soluble myogen fibrin. Myogen fibrin. Myoproteid. — Fiirth has isolated from the muscle-plasma of fish a proteid substance which he terms myoproteid. Nucleins. — These are not present in great quantity in muscular fibre. In dogs' muscle they amount to about 0'37 per cent. The muscles of embryos, the composition of which is more akin to that of young cells, contain more. They are compound albuminous substances in which phosphoric acid is a principal constituent, in combination, in certain cases, with bases such as guanine, xanthine, etc. Neumeister gives the elementary composition of nuclein obtained from the yolk of egg as: — Carbon, 42-11; hydrogen, 6'08 ; nitrogen, 14-73; oxygen, 31-05; sulphur, 0-55; phosphorus, 5-19; and iron, 0-29 per cent. Nucleins are usually insoluble in water and alcohol, but dissolve in dilute alkalies. On treatment with boiling acids or alkalies they yield derivatives of the proteid part of the molecule together with phosphoric acid, and, in certain cases, nuclein bases and their derivatives. Phospho-Carnic Acid. — Siegfried precipitated with ferric chloride from muscle extract previously freed from albumin, a compound containing phosphorus, to which he gave the name of phospho- carnio acid, and which he considered was expended during muscular activity. It can be salted out with ammonium sulphate, and, on dialysis into water, decomposes, yielding phosphoric acid. Enzjrmes of Muscle. — The enzymes pepsin, ptyalin, and maltase have been identified in muscle. It is also probable that other enzymes are present, and the coagulation of the proteids of the plasma, and the acidity of the muscle after death, may possibly be brought about through the agency of bodies of this nature. NITROGENOUS NON-PEOTEID CONSTITUENTS, 7 Colouring Matter of Mxiscle.— Hemoglobin.— The principal colouring matter of the red muscles is hsemoglobin, which Kiihne * was the first to practically demonstrate as being present even in muscular tissue washed completely free from blood. As was mentioned before, t there is a difference in colour in the muscles in different parts of the same animal, and Eanvier | and others have shown that the red colour is a product of the activity of the muscles. Thus, muscles which are continually contracting, like those of the heart, are of a deep red colour, whilst those which are in a comparative state of rest are paler. In birds, for instance, the breast muscles used in flying are dark red, except when, as in the case of the common hen, these are but rarely exercised. Even in the muscles of the same animal, an increase of colour often accompanies an increase of strength — witness the difference in the colour of the flesh of the calf and cow. According to Eanvier the muscle hsemoglobin is not derived from the muscle substance, but originates in the blood-vessels. Colouring Matter of Fish Muscle. — In the muscular tissue of many kinds of fish (e.g. salmon and goldfish), there is, in addition to hsemoglobin, a peculiar rosy red colouring matter, which Krukenberg and Wagner § have found, in the case of the salmon, to be of the nature of a red lipochrome, and not a proteid substance. Myohxmatin. — This is one of a number of pigments (histo- hsematins) discovered by MacMunn || in the muscles of many kinds of animals, and notably in the cardiac muscles of the pigeon. Though giving characteristic spectra they have never been isolated. Myohsematin appears to be capable of forming compounds analogous to the oxyhsemoglobin and methsemoglobin derived from hsemo- globin. MacMunn's theory is that these pigments retain the oxygen which the blood brings to the tissue, until it is required by the latter. Stroma Substance. — This is a simple proteid substance, which cannot be extracted from the sarcoplasmic bodies by neutral reagents. On treatment with dilute potassium hydroxide solution it passes into solution as an albuminate. B.— NITEOGENOTJS NON-PROTEID CONSTITUENTS. Meat Extractives. — When muscular fibre is extracted with boiling water, a considerable proportion of the proteid substances coagulate, and there pass into solution various non-proteid nitro- genous substances, together with other organic bodies and inorganic salts. The nitrogenous bases, to which Gautier gave the name of * Virch. Arch,., 1865, 33, p. 79. t P. 4. t Arch. Fhys., 1874. %ZeU. Biol, 1885, 3, 37-40. || Fhil. Trans. Hoy. Soc, 1886, Pt. 1. 8 FLESH FOODS. leucomaines or physiological alkaloids, are formed normally in the living cell at the expense of the lecithins or of other nitrogenous compounds (see page 217). Classification of Leucomaines. — Gautier classifies the leuco- maines into five groups : — I. Neueinic Leucomaines, including choline, neurine, and betaine. II. Kbeatinic bases, including kreatine, kreatinine, cruso- kreatinine, etc. III. Xanthio bases, including adenine, xanthine, sarcine, etc. IV. Leucomaines of the Fatty Acid Series, e.g. neuridine, cadaverine, gerontine. V. Amido-aoids. I. Netirinic Leucomaines. — As a rule these bases are only found in small quantities in animals. They also occur as ptomaines in the products of the putrefaction of animal matter (c/. page 218). In both cases they appear to be derivatives of lecithins. Choline [CjEuNOj] has been found in small quantity in blood, in glands, and in the yolk of egg. Neurine rCjHjgNO] generally accompanies choline in traces. Betaine [CjHjgNOg] occurs as a normal constituent in certain molluscs, such as the mussel. II. Kreatinic Bases. — The general characteristics of these bases are that they are usually only slightly soluble in water, and nearly insoluble in alcohol. All are precipitated on adding zinc chloride to solutions of their hydrochlorides. All give precipitates with silver nitrate, and most of them with mercuric chloride. They are distinguished from the xanthic bases by containing more hydrogen, and by not being precipitated by copper acetate. Kreatine [C^HgNgOj] (or Methyl-glycocyamine) — ^(^^\n(CH3).CH2.COOH is a feeble base discovered by Chevreul in 1835 in meat broth. It crystallizes in colourless needles and in rhombs which melt at 100° C. It is very soluble in boiling water, less soluble in alcohol, and insoluble in ether. When an acidified solution of kreatine is boiled it is completely converted into its anhydride, kreatinine. C(^^)\N(CH3).CH2.COOH = ^(^^Kn(Ci5ch;.C0 + ^^O- KREATININE. 9 When boiled with barium hydroxide it is hydrated, and yields urea and sarcosine. C4H9N3O2 + H2O = CO(NH2)2 + (NH).CH8.CH2.COOH. Gautier considers that this reaction explains the disappearance of the flesh bases from the tissues. Kreatine is precipitated by sodium phosphomolybdate, and by zinc chloride in the presence of hydrochloric acid and alcohol. Its hydrochloride [C^HgNgOj.HCl] crystallizes in prisms which are non-deliquescent, and but little soluble in alcohol. It gives no precipitate with Bouohardat's reagent (I + KI), and no blue coloration with a mixture of ferric chloride and potassium ferricyanide. Method of Separation. — Kreatine can be isolated from an aqueous extract of meat by boiling, filtering, adding a slight excess of basic lead acetate, or of barium hydroxide, filtering, removing the excess of lead by hydrogen sulphide, or of barium by carbon dioxide, filtering, concentrating the liquid at a low temperature, and puri- fying, by recrystallization, the fine needles which gradually deposit. Kreatine has a slightly bitter taste. It is not very poisonous when injected into animals, but can be transformed by bacteria into the poisonous ptomaine, methyl-guanidine (page 307). It is a common constituent of the muscles of most animals, the average amount found by 0. Voit* being 0-21 to 0-28 per cent. He ob- tained the following quantities from the muscular fibre of various animals :— Frog, 0-21 to 0-35; fox, 0-206 to 0-237 ; ox, 0-219 to 0-276 ; dog, 0-223 to 0-248 ; rabbit, 0-269 to 0-336 ; and man, 0-282 to 0-301 per cent. There appears to be less kreatine present in cardiac muscles than in the voluntary muscles. Rreatinine [C^Hj-NjO]. — This base is invariably present in small quantities in the muscles of the higher animals. In certain fish (e.^. conger) Krukenberg found as much as 0-3 per cent. In cer- tain diseases, such as pneumonia and typhoid fever, the amount obtainable from the urine is largely increased, t Kreatinine forms brilliant prismatic crystals which are readily soluble in cold water (12 parts) and in alcohol (120 parts). In aqueous solution it gradually undergoes hydration, being converted into kreatine ; and the same result is obtained by treating it with dilute alkalies. It is precipitated by sodium phosphomolybdate from acid solu- tions, and by picric acid when the solution is not too dilute. Zinc * Zeit. BwI.,\%69,,\y.^.T!. t G. S. Johnson has shown that the kreatinine ohtained from urinB is not identical with the flesh-kreatinine. Proc, Roy. Soc., xlii. p. 365. 10 FLESH FOODS. chloride precipitates it in crystalline needles [(C4H^N30)2ZnCl2], which are nearly insoluble in cold water, and insoluble in alcohol. It gives a precipitate with mercuric chloride, but not with Bouchardat's reagent (I + KI), or with Selmi's reagent (Fe2Cl, + K3Fe(CN),). It is converted by oxidizing agents into methyl-guanidine, and when heated with barium hydroxide in excess yields methyl- hydantoin. Weyl's Reaction for Kreatinine. — On adding to a cold solution of kreatinine several drops of a dilute solution of sodium nitro- prusside, and then a little dilute sodium hydroxide solution, a red coloration is obtained which changes to yellow, and on acidifying the liquid with acetic acid and warming becomes green and then blue. This reaction is also given by substances allied to kreatinine which contain the group [CHj.CO] united to two atoms of nitrogen. Kreatinine has a greater physiological effect than kreatine. Iso-Kreatirdne. — J. E. Thesen * has isolated this base from the muscle of the haddock. It differs from kreatinine in its colour (yellow crystals), in its solubility in various solvents, reducing action on cupric compounds, and in yielding ammonia instead of methyl- guanidine on oxidation with potassium permanganate. It appears to be converted into kreatinine when allowed to stand in contact with milk of lime. Xantho-Kreatinine [CjHjqN^O]. — This base was discovered by Gautier t in 1882 in muscle and in meat extract. It has often been mistaken for kreatinine, which it resembles in many respects. It crystallizes in yellow spangles, and has a slightly bitter taste, and an odour recalling acetamide. It dissolves in hot concentrated alcohol, and is fairly soluble in cold water. On heating it gives off ammonia and methylamine. Its reaction is amphoteric. Its hydrochloride crystallizes in feathery masses. The platino- chloride is very soluble. Zinc chloride gives a yellowish-white precipitate, consisting of groups of needles. Silver nitrate gives a gelatinous precipitate, and mercuric chloride a yeUowish-white precipitate. No precipitates are given by potassium mercury iodide, cupric acetate, or iodine in potassium iodide. Xantho-kreatinine is poisonous when injected in fairly large quantity, causing extreme lassitude, defecation, and vomiting. * Zeit. phys. Chem., 1897, 24, pp. 1-17. t Le, in profile ; c, a rouleau ; d, three-quarter face ; e, /, crenated ; g, spherical ; L, large white corpuscles ; I, small white corpuscles ; p, granu- lar leucocyte ; », free granulations, x 1000. {Stirling. ) According to Bunge,* the proportion of blood corpuscles in 100 parts of blood is, in the case of different animals, as follows : horse, 53; pig, 43-5; ox, 35; -dog, 35-7. Arouet* found human blood to contain on the average 48 per cent. Colour. — This is due to haemoglobin, which, in the form of oxyhsemoglobin, composes about 13 per cent, of the total blood, 40 per cent, of the moist corpuscles, and 95 per cent, of their total organic matter. The other constituents of the corpuscles are grouped together under the term stroma. Examined under the microscope, the individual corpuscles are transparent, and have a faint yellowish-green colour. OxyTixmoglohin. — This is the colouring matter of the bright red arterial blood. It can be isolated from the stroma in a crystalline form. The blood corpuscles are separated from the defibrinated blood by means of centrifugal action, washed free from serum with a solution of sodium chloride, shaken with ether, transferred to a separating funnel with a small quantity of water, and the lower aqueous solution filtered. The filtrate is cooled to zero, mixed with a fourth of its volume of alcohol also at 0° C, and allowed to stand for twenty-four hours at a temperature of from -2° to - 10° C. The crystals of oxyhaemoglobin which have deposited are pressed between filter paper, and purified by recrystallization. Differences in the Oxyhemoglobin Crystals obtained from the Blood of Different Animals. — The crystals obtained by the method described above vary greatly in chemical composition, crystalline form, and solubility (see fig. 12). As an instance of the variation in composition the following * Quoted by Neumeister, Phys. Chem., p. 559. HEMOGLOBIN CRYSTALS FEO^I BLOOD. 35 analysis of different specimens of crystals from horse-blood may be quoted : — Carbon. Iron. Sulphur. Hoppe-Seyler, . . 54-87 0-47 0-65 Zinoffsky, . . . 51-15 0-34 0-39 The water of crystallization in different varieties of oxyhsemo- globin varies from 3 to 10 per cent. Fig. 12. — Haemoglobin crystals from Blood, a, b, human ; c, cat ; d, guinea-pig ; e, hamster ; /, squirrel. {Landois and Stirling, ) As regards crystalline form, the oxyhsemoglobin of human blood is obtained in microscopic rhombic needles, and that of the horse in quadrilateral prisms often several millimetres in length. The blood of the guinea-pig, rat, and many birds yield rhombic tetra- hedra, while from that of the squirrel hexagonal plates are deposited. The difference in solubility is shown by the fact that the crystals are easily prepared from the blood of the guinea-pig, rat, and squirrel, and fairly readily from that of the horse, dog, cat, and mouse, but only with considerable difficulty in the case of the pig and ox. Identification of Oxyhsemoglobin. — The most characteristic pro- 36 FLESH FOODS. perty of oxyhaemoglobin is its absorption spectrum. In a suitable degree of dilution it shows two bands, one at D, and the other, which is broader and less defined, at E. On continued dilution the latter is the first to disappear (c/. fig. 15). Quantitative Estimation of Oxyhsemogloiin. — The amount of oxyheemoglobin in blood, or in liquids containing blood, can be approximately estimated by determining the amount of iron in the ash. The oxyhsemoglobin from horses' blood contains from 0'34 1 ' Fir. 13. — Fleisohl's heemometer. K, red-coloured wedge of glass moved by R ; G, mixing vessel with two compartments, a and a! ; M, table, with hole to read o£f percentage of hsemoglobin on scale P ; 2" to move K\ S, mirror of plaster of Paris. (Lcmdois and Stirling. ) to 0'47 per cent, of iron, and 0-42 per cent, may be taken as the average amount in dry oxyhsemoglobin in general. The method most frequently employed, however, is Hoppe- Seyler's colorimetrio process,* or one of its modifications. This consists in diluting a measured quantity of blood with water until it matches the colour of a solution containing a known quantity of pure crystalline oxyhsemoglobin. The Nessler tubes, and the process recommended by Hehner t for the determination of ammonia in water, are well adapted for this colorimetrio process. G. Oliver f advocates the use of Lovibond's tintometer and standard colour glasses, and, according to Halliburton, % this gives a better result with diluted blood than any other colorimetrio process. * Zeit. physiol. Chem., 1892, xvi. p. 505. t Analyst, 1877, ii. p. 180. J Kirk's Physiology, p. 597. DEEITATIYES OF HAEMOGLOBIN. 37 Fleischl's hsemometer, which is one of those most frequently used, is illustrated in fig. 13. Reduction of Oxyluemoglobin. — The oxygen in oxyhsemoglobin is only feebly combined, and is completely liberated in vacuo. It is known as 'respiratory oxygen,' and the iron in the proteid mole- cule probably plays some part in its addition. Besides being re- duced in a vacuum, oxyheemoglobin is also converted into hfemo- globin by passing a current of an inert gas such as hydrogen, carbon dioxide, or nitrogen through a solution of it, by the addi- tion of reducing agents such as ammonium sulphide, and by the products of putrefaction. ^ Pseudo-Hxmogloiin.' — Certain reducing agents, suchas potassium hydro-sulphide, only cause a partial reduction of oxyheemoglobin, and an intermediate product is formed with the same spectrum as the com- pletely reduced oxyhsemoglobin, but still containing some oxygen. Hssmoglobin. — This is obtained by the complete reduction of oxyhsemoglobin, and is the dark purple colouring matter of the venous blood. It combines energetically with oxygen and carbon monoxide. Its spectrum is shown in fig. 15. Hxmatin. — On heating an aqueous solution of oxyhfemoglobin to about 80° C. it undergoes decomposition, and an amorphous pre- cipitate is deposited, which has a composition corresponding to the formula C32H32N^O^Fe. Hsematin has a bluish-black metaUic lustre, and can be heated to 180° C. without decomposition. Hxmin, — This is the hydrochloric acid compound of hsematin anhydride, and has the formula CgjHgoN^OgFe.HCl. It is precipi- tated in characteristic crystals on heating a solution of oxyhsemo- globin in glacial acetic acid containing a little sodium chloride. The crystals are minute rhombic plates with a bluish-black metallic lustre. They are insoluble in water, alcohol, and ether, slightly soluble in acetic acid and dilute mineral acids, and easily soluble in alkaline liquids and acidified alcohol. The diflference in the form of hsemin crystals from diiTerent kinds of blood is seen in fig. 14. Hmmatin Acid. — This has recently been prepared by Kuster* by oxidizing hsematin dissolved in acetic acid. It is a crystalline, dibasic acid, and has the formula CgHj^Oj. Hsemo-chromogen, or reduced hsematin, is produced by the action of acids and alkalies on hsemoglobin in the absence of oxygen. In alkaline solution it rapidly absorbs oxygen from the air, changing to hajmatin. In acid solution it gradually loses its iron, and becomes converted into hsemato-porphyrin. Hsemato-porphyrin. — When hsematin or hsemin crystals are treated with concentrated sulphuric acid, fuming hydrochloric acid, or acetic acid and hydrobromic acid, the iron is completely * BericUe, 1897, p. 105. 38 FLESH FOODS. split off, and, ou dilution, a colouring matter is obtained. This has the composition C32H35N"^05, and was named haemato-porphyrin by Hoppe-Seyler. Methxmoglohin. — By acting on the colouring matter of blood with oxidizing agents, such as potassium permanganate, hydrogen peroxide, or ozone, the oxyhsemoglobin undergoes a molecular change, and an isomeric compound with a distinctive spectrum is formed. It can be reconverted into oxyheemoglobin by dissolving /-:' '4 e ^ \ % Fig. 14. — Haemin crystals. 1, human ; 2, seal ; 3, calf; 4, pig ; 5, lamb ; 6, pike ; 7, rabbit. {Landois and Stirling.) it in dilute sodium hydroxide solution, and adding a reducing agent such as ammonium sulphide. Carbon Monoxide HxmogloUn is a compound of haemoglobin with carbon monoxide, and is produced in the blood in cases of poisoning by that gas (c/. fig. 15). Spectra of Hxmoglohin and its Derivatives. — The spectra of haemoglobin and of some of its most characteristic compounds are shown in the accompanying figure (fig. 15). THE WHITE CORPUSCLES. The white corpuscles, or leucocytes, are present in the blood in much smaller quantity than the red corpuscles, the normal ratio being about 1 : 350. They are also considerably larger, being usually about ^^d o °f ^^ i'^'^^ ™ diameter. In form they are irregular, and are continually altering their shape after the manner of the amosha. They are composed of a granvdar sub- stance of a protoplasmic nature containing a rounded nucleus, which can readily be made visible by treating the white corpuscles with very dilute acetic acid. This nucleus assumes a darker colour than the rest of the corpuscle when stained with carmine. Fig. 16 represents the appearance of the white corpuscles when treated with different reagents. SPECTKA OF HEMOGLOBIN COMPOUNDS. 39 OTHEE SMALL BOBIES IN BLOOD. In addition to the corpuscles, blood contains small irregularly- shaped bodies containing protoplasm, to which the name of Wood platelets or ' hmmatohlasts ' has been given. There also occur here Red. Orange. Yellow. Green. Cyan Blue. Oxyhsemo- globin, 0-8 %. Oxyhsemo- globin, 0-18 %. Carbonic Oxide Hsemo- globin. Reduced Haemo- globin. Methjfnio- globin in Acid Solu- tion. Hsematin in Alkaline Solution. Hfemo- chromogen in Alkaline Solution. i"r"T"j"'T^"l"'T"T"T"'l""| " 1 1 1" ' ' r ■ ' ' I Hsematin 4o 5o 00 A a B C D E F Fig. 15. — Spectra of haemoglobin and its compounds. {Landois and Stirling. ) and there small particles, some of which contain a brown or black pigment. These are about five times the size of the red cor- puscles, and possibly have their origin in the spleen. The colour- less particles which are met with in the blood are probably frag- ments of broken-up white corpuscles. 40 FLESH FOODS. THE BLOOD PLASMA. This contains about 8 per cent, of solid matter, chiefly of a pro- teid nature. The amount of inorganic matter is about 075 per cent. Proteids of the Plasma. — The albuminous substances contained in blood plasma are chiefly globulins. Serum albumin is also present in small proportion, the ratio between it and the globulins varying in difi'erent species of animals. The plasma of cold- blooded animals contains the least serum albumin. '.•9" ( » \» r Fig. 16. — White corpuscles under diflferent reagents. A, human white blood corpuscles without any reagent ; £, after the action of water ; C, after acetic acid ; B, frog's corpuscles ; changes of shape due to amoeboid move- ment ; E, fibrils of fibrin from coagulated blood ; F, elementary granules. {Landois and Stirling.) Metaglohulin or Fibrinogen. — This is the most important of the proteid constituents. It can be separated from the globulins and serum albumin by adding sodium chloride to its solution. When the amount of sodium chloride reaches 16 per cent., the fibrinogen is precipitated, whilst the globulins remain in solution until the liquid has been saturated with salt. On heating fibrinogen in aqueous solution to from 56° to 60° C, it is decomposed into two globulins, one of which is precipitated, while the other remains in solution until the temperature reaches 65° C. After removing the sodium chloride by means of dialysis, fib- rinogen is obtained in white flakes, which readily agglomerate into PKOTEIDS OF BLOOD PLASMA. 41 an elastic mass. When left in water it undergoes an alteration and becomes insoluble in dilute salt solutions. ' Thrombin ' or ' Fibrin Ferment.' — According to A. Schmidt * and others the coagulation of fibrinogen is brought about by an enzyme, the so-called ' thrombin ' or ' fibrin ferment,' which is derived from a substance of a similar nature, 'prothrombin,' con- tained in the corpuscles of the blood, more especially the white corpuscles. It can be obtained from the defibrinated blood or from the blood serum by leaving the liquid in contact with strong alcohol for several months, and extracting the air-dried deposit with a little water. This aqueous extract contains the active enzyme, and rapidly causes a solution of fibrinogen to coagulate in the presence of a small quantity of calcium chloride. Fibrin. — On coagulation fibrinogen is decomposed into two pro- teid bodies— ^6rm and fibrin globulin. The quantity of fibrin obtained from blood only amounts to from O'l to 0'4 per cent., although from its voluminous nature it appears considerably more. When deposited during the coagulation of blood it is very impure, being mixed with serum globulin and constituents of the white corpuscles. The pure substance can be prepared by treating a solution of pure fibrinogen containing calcium chloride with the fibrin ferment. Pure fibrin is insoluble in water and (at first) in neutral saline liquids, but is completely soluble in dilute acids and alkalies after remaining in contact with them for some days, and in dilute salt solutions after some weeks. Fibrin Globulin. — This substance is formed together with fibrin during the coagulation of fibrinogen. It is also produced together with another proteid on heating fibrinogen to 56-60° C. On evaporating its aqueous solution fibrin globulin is converted into a substance of an albumose character. Paraglobulin or Serum Globulin. — When blood coagulates (with deposition of the altered fibrinogen) this proteid is found in an unaltered state in the serum. A solution of paraglobulin in a 10 per cent, solution of sodium chloride coagulates at 75° C. It can be precipitated by adding to its solution an equal volume of a saturated solution of ammonium sulphate. Serum Albumin. — This is also found in the serum after coagula- tion of the blood and can be isolated by precipitating the globulins by saturating the liquid with magnesium sulphate at 30° C, and then adding dilute acetic acid to the filtrate. Pure serum albumin coagulates from its aqueous solution at 50° C, but when salts are also present the coagulation temperature is considerably raised. Yellow Colouring Matters of Blood Serum. — The faint yellow colour of the blood serum of man and most animals is due to the * Neumeister, loc. cit., p. 594. 42 FLESH FOODS. presence of a dissolved colouring matter (lipoclirome), which can be extracted by means of amyl alcohol. This colour is much more pronounced in certain animals than in others. It is well marked, for instance, in the serum of the ox, pigeon, hen, and tortoise, whilst rabbits' serum is almost colourless. Under the name ' lipo- chrome' are classified various non-nitrogenous animal colouring matters, the constitution of which has not been determined. Hammarsten * found that the blood serum of the horse always contained a small quantity of bilirubin, one of the colouring sub- stances of the bile. The amount of this appears to vary in different horses. Fat. — This may amount to as much as 1 per cent, in the case of animals whose food has contained a large amount of fat. It can be extracted from the serum with ether. Cholesterin and lecithin are invariably present in small pro- portions. Glucose. — This is a constant constituent in varying quantity in the blood serum of different animals, but it never appears to exceed 0'2 per cent, of the original blood. Other reducing bodies, in- cluding gums, are also present in traces. Traces of sarcolactic acid, kreatine, uric acid, and urea are also present. Inorganic Constituents of Plasma. — These are found partly in combination with the proteids and partly in the free state. Bunge t obtained the following mean results in his examination of the blood serum of the horse, ox and pig : — Potassium oxide, 0'026 ; sodium oxide, 0'435 ; calcium oxide, 0'013 ; magnesium oxide, 0'004 ; chlorine, 0-369 ; phosphoric acid, 0-022 ; total, 0-869 per cent. The sodium chloride is in the free state, and not in combination with the proteids. A considerable proportion of the sodium is in the form of sodium bicarbonate. In addition to these salts traces of fluorine compounds have also been found. Gases in Blood. — -These are oxygen, carbon dioxide, and nitro- gen. Arterial blood contains more oxygen than venous blood, while the latter is richer in carbon dioxide. Piliiger J obtained from the arterial blood of a dog, 21 per cent, by volume of oxygen, and from the venous blood 1 2 per cent. In the case of the carbon dioxide the respective quantities were 38 and 46 per cent, by volume. There is not this difference to be observed in the amount of nitro- gen, which, in each kind of blood, is about 2 per cent. The carbon dioxide is present partly in the form of sodium bicar- bonate, and the remainder is probably loosely combined with some of the proteid substances. Practically the whole of the oxygen is in chemical combination with the hsemoglobin of the red corpuscles. * Neumeister, loc. cit., p. 585. t 2eit. Biol., 1876, 12, p. 191. J Neumeister, loc. cit., p. 600. CONSTITUENTS OF BLOOD IN OXEN AND HOKSES. 43 ULTIMATE COMPOSITION OF BLOOD. According to the analysis of Playfair and Boeckmann, the dried blood of the ox has the following elementary composition : — Car- bon, 57-9 ; hydrogen, 7-1; nitrogen, 17-4; oxygen, 19-2; ash, 4-4 per cent, ■which is identical flesh. This would correspond to the formula C^jHgpNjgOis, with that found by the same chemists for PROXIMATE COMPOSITION OF BLOOD. E. Abderhalden * gives the following table of the quantity of the various constituents in the blood of the ox and horse. COMPOSITION' OF THE BLOOD OF THE OX AND HOESE. Grammes in 1000 Grammes. Ox. Horse. Blood. Blood Serum. Blood Corpus- cles. Blood. Blood Serum. Blood Corpus- cles. Water, . 808'9 913-64 591-858 749-02 902-05 61315 Solid Matter, . 191 1 86-36 408-141 250-98 97-95 386-84 Haemoglobin, . 82-0 251-92 166-9 315-08 ... . ' Albumin, , 90-9 72-5 129-02 69-7 84-24 56-78 Sugar, 0-7 105 0-526 1-176 Cholesterin, 1-935 1-238 3'-'379 0-346 0-298 0-388 Lecithin, , 2-349 1675 3-748 2-913 1-720 3-973 Fat, . 0-567 0-926 • •• 0-611 1-300 ... Phosphoric Acid in Nucleins, . 0267 0-0133 0-0546 0-060 0-020 0-095 Sodium Oxide, . 3-635 4-312 2-2322 2-091 4-434 Potassium Oxide, 1-407 0-255 0-722 2-738 0-163 4'-'935 Iron Oxide, 0-544 .t< 1-671 0-828 1-563 Calcium Oxide, . 0-069 01194 0-051 0-1113 Magnesium Oxide, 0-0356 0-0446 0-0172 0-064 0-045 0-0809 Chlorine, . 3-079 3-69 1-8129 2-785 3-726 1-949 Phosphoric Acid, 0-4038 0-244 0-7348 1-120 0-240 1-901 Phosphoric Acid in inorganic combination, . 0-1711 0-0847 0-3502 0-806 0-0715 1-458 Zeit. physiol. Chem., 1897, 23, p. 521. 44 FLESH FOODS. IDENTIFICATION OP BLOOD IN STAINS, ETC. This belongs rather to the domain of forensic chemistry than to the subjects treated of in the present work, and hence no exhaus- tive description of the methods which have been recommended for the purpose is attempted here. The following details may, how- ever, be found serviceable. Alteration of Dried Blood on Heating* — When dried blood is heated for an hour at 100° C, it still remains soluble in water, cold saturated solutions of borax, concentrated solutions of potassium cyanide, dilute sodium hydroxide solution, ammonium hydroxide, acidulated alcohol, and glacial acetic acid. After being heated for an hour at 120° C, it becomes insoluble in water, and less soluble in the other liquids, with the exception of sodium hydroxide solution, and acetic acid, in which it dissolves as readily as before. After an hour at 140° to 180° C, it is only slightly soluble in ammonium hydroxide, but more so in sodium hydroxide solution and glacial acetic acid, which must therefore be regarded as the most suitable solvents. Preparation of Hxmin Crystals. — This is generally looked upon as the most characteristic test for blood. By using potassium iodide instead of sodium chloride, Strzyzowski * was able to detect as little as 0-000025 gramme. In his method a trace of the sub- stance under examination is mixed with a drop of a 0-2 per cent, solution of aqueous potassium iodide on a glass slide, and after the liquid has evaporated, a cover glass is placed over the residue, and a little glacial acetic acid introduced. The slide is gently heated until the acetic acid commences to boil, and when cold is examined under the microscope. Spectroscopical Examination. — This often furnishes corroborative evidence. The absorption spectra of some of the colouring sub- stances, obtained from blood, are shown on p. 39. Detection of Blood in the Presence of Iron. — It is often impos- sible to obtain htemin crystals from blood which has become insol- uble from being left in contact with iron. In such cases Gantter f recommends the use of hydrogen peroxide as a reagent. A drop of the solution, or a fragment of the insoluble substance moistened with water, is made feebly alkaline, and a drop of hydrogen per- oxide added. If the slightest trace of blood be present, numerous bubbles of oxygen are libei-ated, which, in a short time, coalesce into a white scum. Unfortunately, other animal fluids [e.g. pus) behave in a similar * Zeit. anal. Cliem., 1898, p. 467. t Ibid., 1895, pp. 159, 160. H^MOLYMPH AND OXYHiEMOCYANIN. 45 manner, so that a positive result is not absolutely conclusive. Still the test is of value as confirmatory evidence. THE BLOOD OF INVERTEBRATE ANIMALS. HsBmolymph. — In worms and the majority of molluscs, the liquid which corresponds to the blood in higher animals, fulfils the functions of blood and lymph, and has hence received the name of ' hxmolymph.' It is a liquid rich in albuminous sub- stances, and in many cases shows signs of fibrin coagulation. It contains white corpuscles (leucocytes), and in some few instances, red corpuscles, but the latter are rare. Instead of red corpuscles, free oxyhsemoglobin is not uufrequently found in solution, its function being probably of a respiratory nature, and the violet or purple colouring matter in the hsemolymph of some invertebrata appears to play a similar part. Oxyhxmocyanin. — In certain arthropoda and molluscs (e.g. the crab, oyster, and snail), the hsemolymph has a bright blue colour, due to the presence of an albuminous colouring matter, which takes the place of the oxyhaemoglobin in red blood, but which contains copper instead of iron. This pigment, known as ' oxy- hxmocyanin,' can be partially separated from the haemolymph by dialysis, but it readily redissolves in a dilute solution of sodium chloride. It coagulates at 68° to 69° C, and, like the globulins, can be precipitated by saturating its solution with magnesium sul- phate or sodium chloride. When acted upon by acids, it is decomposed into albumin, and a colouring substance which contains a large proportion of copper, and corresponds to hxmatin. When the respiratory oxygen is withdrawn from it in vacuo, or by means of reducing agents, a colourless compound (hxmocyanin) is left, which rapidly becomes blue again on exposure to the air. Neither of these compounds appears to have a very definite absorption spectrum. Other pigments, of the nature of lipochromes, have also been found in hsemolymph of various origin, but these have not been proved to have any definite respiratory functions. CHAPTER III. THE FLESH OF DIFFEKENT ANIMALS. There is no more difficult problem in analytical chemistry than the detection of one kind of flesh when mixed with another. It is true that each has its own characteristic odour, but the substance producing this is probably present in too minute a quantity to be isolated from the flesh or separated from a mixture of such bodies. Then, too, the chemical differences which have been recorded by various observers are in most cases incapable of giving reliable data, owing to the variation in the composition of the flesh of different animals of the same species, and the similarity of that of animals of different species. In some cases an examination of the fat of the adipose tissue connected with the muscle or of the fat within the muscular tissue itself may be of service, as, for instance, in the detection of horse- flesh in meat preparations,* and for that reason the chemical and physical constants of the fat of different animals are given at length in the following pages. Sometimes the flesh contains a considerable proportion of a given constituent, which is either absent altogether or only present in smaller amounts in other kinds of flesh, as, for example, isokrea- tinine in the flesh of the haddock, betaine in the mussel, and gly- cogen in horse flesh. In such cases a quantitative determination of the substance may give an approximate idea of the amount of the original flesh. It is only, however, in the case of horse-flesh that such a method has as yet been worked out with any degree of success. C. Virchow t made experiments to determine whether there was a difference in the amount of soluble extractives in different kinds of flesh. After removing all visible fat, the finely divided flesh was extracted with water at 45° C, the extract boiled, filtered from the coagulated albumin, an aliquot part of the filtrate evapo- rated, and the residue dried and weighed. His results showed that * Cf. p. Ul. t B,. Virchow's Archiv, 1881, p. 543. THE FLESH OF DOMESTIC ANIMALS. 47 CO I— I O )— I CO O ft Eq O CO W w EH o o t/2 o :^ o o ^ s n . t>i i-l (N CO : 'o OS -^ oa 00 10 C^ o'a rH Tft i-C i-( I-t ' |zi a <) I '^ ■ ^ g. t^o cq CO . 03 to cq 4jt Ah CO rH 10 in .^ ■^ Ah 00 rH CO 1 i-i ?-< rH I— < f-H i-t I-H r-l . *" *>•£ CD CO t^ CO 10 ■"it t^ CO ■"*< CO cq 1-H CD 3 -t^ CO Wi 00 00 cq P 00 W t^. yi ip p «3 Tjl 6^ ^ cq OS t^ Ca i- «D CO Ah CO 4»( CI O) <© rH cq cq CO (N t* Cfl Tjt fci ii (S« £ ■ © ^ DD M . OS OS CO COI>- W5 OS ^ Oi «3 »rs p CO M iCi CO r* 9° rH OS CD s » »n -ii* t^ 01 «o 00 (TO urs .-1 00 CO ClD CO ITS +3^ cor^ 00 CO 00 CO 01 CO (>- cq ir^ 10 OS 00 •^ 3 !2;a! •d cq -^ CO t*(M CO CO CO cq t^ cq rH OS r-i rH p CO CO »p OS CO r* rH p rH p »-H r-t i-H rH I^ i-H Ah Ah Ah > i rH t* 10 (O : th ; ■^ : P ; ; : : : : 9 "?* '■ 2 * * • 6 ■ • Ah !^« *3 H s 00 .-H Tj( CO r-l CM 1—1 f- •<:t< I-H T(1 CO 6 -t^ ■?•■?* ^ t- J>* T** 00 to i>- CO 00 ip tp -Kp & ana r-i !>■ i-l t»o 00 r^ CO »o s (N cq CO I-H (5 CO d m 10 to i-H to ■* 00 CO (M t-H ■*s 000 ^ 9* ^ 00 »o 00 CO 9 7^ la cq p cot* CO OS 00 Oi CO t- 4i< 00 « A< .^1 i-((M (N i-H CN I-H tH r-H i-H 1-t cq rH cq cq !2;M fe 10 eo t^ CD U3 I-" (N I-H OS ot^ OS -g p p 00 p CO CO 00 CO p T* ^ CO CO M c3 CO cq i> eb w 00 COW t^ cq A^ OS Afi ^ IQ t^t^ lr*t"* i>-t-- »OJ>- ■"*< I:* CD i>.Jr* -.^ g S 3 3- 1 ^"1" . f^T3 a * - pT - c « d ^ s « ^ 'i^ S ai .3^ 3J 'aas v-^ ^T-' ^-1— ' w-' ' r— ' 3 1 §■ 'a 1 t4-~ Ph 48 FLESH FOODS. there was no appreciable difference in the total amount of ex- tractives yielded by the muscular fibre of different species, or of different animals of the same species, whatever their age, condition, or food. In the case of the ox his mean results were : — Ox (he Fat. althy). Lean. Ox (diseased). Calf. Water, . . . .76-68 76-25 77-47 77-61 per cent. Extractives, . . .373 3-53 3-87 3-82 ,, calculated on dry substance, . 15 78 15-09 17-19 17-22 In the description given in this chapter of the varieties of flesh more commonly used as food, a classification into four groups has been adopted for the purpose of convenience: — (1) Domestic animals ; (2) Game and birds ; (3) Vertebrate fish ; (4) Invertebrata. The word ' flesh ' is here chiefly used in its colloquial sense of fat and lean meat. THE FLESH OP DOMESTIC ANIMALS. There is, in general, a marked distinction between the flesh of the common domestic animals and birds and of ' game,' the muscular tissue of the former being of a coarser texture, and undergoing putrefactive decomposition more readily than that of the latter. This difference must be chiefly attributed to the difference in food, environment, and habits of life, for when a domestic animal is placed under the same conditions as a wild one its flesh in the course of future generations assumes the finer texture and other characteristics of ' game,' an instance of which is seen in the case of Welsh mountain mutton. The sex of an animal often has an influence on the physical characteristics of its flesh, and, as a rule, the flesh of the female is more tender, but has less flavour, than that of the male. The table on p. 47, compiled from those of Kdnig,* gives the mean results of the analyses of different chemists. The subjoined table on p. 49 by Strohmer t gives an idea of the comparative composition of the chief animals in this group re- garded from another point of view. The average composition of commercial lean meat, freed from bone and all visible fat, is given by Voit as : — Water, 75-9 ; pro- teids, 18-4; collagenous substance, 1-6; fat, 0-9 ; extractives, 1-9 ; and ash, 1-3 per cent. * Nahr. u. Geniissmittel, ii. 110. f Die Ernahrung des Menschen, p. 112. CHAEACTERISTICS OF BEEF. 49 Age of Animal, years, Living Weight, kilos. Contained per cent. — Bone Muscular flesh, . . Fat Entrails, skin, etc. , Butcher's refuse, . Fit for food, . . . Fat Calf. 258 12-4 45-5 11-0 31-1 37-9 62-1 Medium Ox. 4 1232 11-4 47-9 12-7 28-0 35-2 64-8 Fat Ox. 4 1419 10-4 40-2 25-8 23-6 Fat Lamb. 84 8-1 36-9 23-7 31 '3 40-2 59-8 Lean Sheep, 1 97 9-5 37-5 14-8 38-2 46-7 53 '3 Fat Sheep, n 107 7-0 29-8 32-4 30-8 42-5 57-5 Lean Pig. 93 8-3 47-6 20 '0 24-1 26-3 73-7 Fat Pig- 185 5-6 37-3 39-4 17-7 17-2 82-8 BEEF. Characteristics. — The muscular tissue of the ox has a somewhat closer texture than that of the other animals in the preceding table, and retains more of the blood. In certain parts the flesh is nearly free from visible fat, in others the fat is intermingled with the lean, giving a mottled appearance. The connective tissue of an animal in good condition glistens on exposure to the air, and is fairly moist, though no water should exude from it. The proportion of muscular tissue, fat, etc., contained in an ox are shown in the following table of Lawes and Gilbert : — Per cent. Condition. Moderately fat. Fat, . 3 years Bones. 11-4 10-4 Muscle. 47-9 40-2 Fat. Skin, etc. 12-7 28-0 25-8 23-6 Influence of Sex. — The flesh of the cow is more tender than that of the ox, but has somewhat less flavour. That of the bull has a rank, strong taste, and in consequence bull-beef may only be exposed for sale in this country with a plain notification as to its nature.* In general it may be stated that the flesh of the male uncastrated animal has a more pronounced taste and smell than that of the female or castrated male. Composition. — According to the analyses of Playfair and Boeck- mann,t beef has the following ultimate composition : — Carbon. Hydrogen. Nitrogen. Oxygen. Ash. Playfair, . . 61-83 7-57 15-01 2137 4-23 Boeckmann, . 51-89 7-59 1505 21-24 4-23 * Public Health Act, 1875, § 261. + Liebig,' Organic Chemistry, p. 314. 50 PLESH FOODS. Almen * found its proximate percentage composition to be : — Water, 76'76; solid matter, 23-24; proteids, 17-88; fat, 2-24; insoluble salts, 0-65; and soluble salts, 0-48. As an instance of the variation in tbe composition of the flesh from different parts of the same animal, the following results may be quoted from Kbnig : — Flesh of Fat Ox from Per Cent. Per Cent. Calculated on Dry Substance. Water. Nitrogenous Substances. Pat. Ash. Nitrogenous Substances. rat. Nitrogen. Neck, . . Shoulder, 73-5 50-5 19-5 14-5 5-8 34-0 1-2 1-0 73-58 39-29 21-89 68-69 11-77 4-68 Digestibility. — Judging by the results of artificial digestion experiments, the muscular tissue of the ox is the most digestible of all the kinds of flesh ordinarily eaten, f The Fat. — Beef-fat shows considerable variation in colour according to the age and food of the animals. In young bulls it is whiter than in cows and bullocks, and the fat of animals fed on oil-cake is much yellower than that of animals fed on grass or corn. The fat of certain breeds of cattle, notably those of Jersey and Guernsey, is of a deep yellow colour. In composition beef-fat consists almost entirely of the glycerides of stearic, palmitic, and oleic acids, and is much more constant in its consistency and composition than the fat of the sheep and pig, although the variation in the fat from different parts of the body is considerable. Lewkowitsch J gives the ratio of stearin to palmitin as about 1 :1, a statement which is borne out by Hehner and Mitchell,§ who found a specimen of fresh beef ' stearin ' (i.e. fat from which the liquid portion had been almost entirely removed, the iodine value being only 2) to contain 50 per cent, of the glyceride of stearic acid, the remainder being, presumably, palmitin. Beef-fat has a characteristic odour, and on crystallization from ether gives fan-shaped bunches of needle-shaped crystals consisting of a mixture of palmitin and stearin. This has been largely employed as a test for the presence of beef-fat in lard. || Falck, Bas Fleisch, p. 346. : Oils, Fats, and Waxes, 1895, p. 482. Of. p. 91. t Cf. p. 87. § Analyst, 1896, p. 328. VEAL AND MUTTON. 51 Lewkowitsoh* gives the following Table (see p. 52), by Leopold Mayer, of the composition and constants of the fat taken from different parts of the body of a Hungarian ox, three years old. The iodine value of beef-fat varies, according to different ob- servers, from 35-4 (B'ilsinger) to 44 (Wilson), and that of the liquid fatty acids from 92 to 92-5 (Wallenstein and Finck). Farnsteiner has found traces of linolic acid and of linolenic acid in ox-tallow (p. 101). VEAL. Characteristics. — The flesh of the calf is of a paler colour and less consistent than beef. It was formerly a general practice to increase the paleness by bleeding the animal before death — a custom which has happily fallen into disuse in this country.! In Germany it is illegal to kill a calf for food at a younger age than ten or twelve days, while a month is the time prescribed iu a corresponding Austrian regulation. The muscular tissue of an embryo or of a newly-born calf is watery, and the fat has a soapy appearance and a distinctive odour. According to Walley t the flesh of a young calf closely resembles that of a dog, and the same authority states that veal is occa- sionally substituted for chicken in certain food pastes. Lawes and Gilbert found a fat calf six months old to have the following percentage composition : bone, 12-4 ; muscle, 45'5 ; fat, 11*0; skin, etc., STL The general composition of calf's flesh is given in the table on page 47, and the fat has practically the same chemical character- istics as beef-fat. Veal contains much less iron and alkali salts than beef, but, on the other hand, is richer in connective tissue. According to StafFel J the ash, after deducting the sodium chloride, has the following percentage composition : potassium phosphate, 68*05; sodium phosphate, 5'66 ; calcium phosphate, 3"72; magnesium phosphate, 6'21 ; free phosphoric acid, 15'10; ferric oxide, 0'30 ; and silica, 0'92. MUTTON. Characteristics. — The muscular tissue of the sheep differs from beef in its colour and in being less firm in texture. The flesh of an old ram, however, has a marked colour, and is firm and tough. * Loe. cit., p. 480. t Walley, Meat Inspection, p. 15. X Liebig, Letters on Chemistry, 52 FLESH FOODS. o o H o Eh O H H O w o ^ t3 6D "3.S ■ CO Oi p o oo 00 CD -S • 00 CO iM CN rH CO ■«*< ■* w vn CO CD .— . f— ■ lO o g 3 >^ ^ip J;^ rH p *P ?* ■^ ■"S" i—t t-H OS t^ OO CO S2;, iCt lO '* t3( CO CO « T^ an " ■E3 <1 >> c3 1 Sag fp 1-H Ml p CO p CO OS 0-J3 a o O o o o OS g-^ (M CI (N c^ (M 1-t ra 60 . ■■3 .go ia 00 T* T** p r-i ■So" t^ r^ I-- " ti . a J si -o g St ^^g § ^ lb' >* v Oladdini Wiley. Teunille von Eau Valenta. Dietericl 1 f < 1 03 IstS 1 1 0) 0) C 3 § Mi* : . . ■■i'- ■■■■■■ • ■ is" "P So « . CD a=«aw . ffl r-l lj^^ ''' 0-. H ta -a OOO f^' . ?> •3 cneq-jK t-OMCOO) COttl 04 J < ^ SSSSB i° GO o P oo HH oooo o-t»n 00 CO la . S P g Ph IH uaeOr-' t-t-qo MOO fe OMW 00 00 43 J?- lisN t-- 6> o ■* "* &0 a m CB / ID ^5 o ■ A » • ■ * lO -* Sm fl ^4* si" 00 rt r-J To (N tHS^CO P J h V,— ->.'—*.— - CO ^ oJ (M 00 S 3 ■^ -<7' t— i>- JIh — < OS a 03 vnun ^ 1 w> Oi Oi Oi to OS 00 tJ ^ OT . CD s-s la t^\a ^^ OS 00 Oi A- 10 1 Oi Oi Oi 01 rH r-t r-H rH l-H \a 00-43 OS i-i cn , m 3 CO i-i r^ r^ CO 3'^ "0 CO Tji 00 -^ CO p w . QO :=J "3 QO O -. 00 cc r^ cjo 00 CO 00 i~\ d TS 01 ■<* o -S QO «p Oi Tji as 7P l-H HH & A^ 4*< Ah OS i>- c^ ITS i : 00 t* CO t-- t^ 00 CO QO 00 t-^ Solidifi- cation Point. F. Acids u^ CO (N t» l>- CO (N CO CO CO ■^ CO ^ mi III-* co 1 1 1 us rp 00 I— c CO C^ .-< -* CO -5i '■^J^ CO CO CO CO urs m y CO '* tM Oi . l>-CO c^ „,^^„ (N CO 40 CO CO CO 1 H «ti 1 1 1 (N CO 00 !>. \a Is to CM i-H la -^ iCi ^ CO CO Ph CO CO CO bC s M -4J +3 in t^ CO CO CO s 1 1 OS Tj< «3 00 1 00 CO CO CO ^ >* s >. OS 0^ en jp (N CO i-H 'i^ OS r-»(M n OS CO CO CO !>. 10 <© .-' CO 1ft =0 r-C ■-< i-H CM .-H ^H '"' ■"000 <1 _jj OS OJ OS 01 < OS d s ■ ■ ' ' in ' C5 ce -^ ^ -a •rj S a i S § g 1 a 4J -2 ^ C! 60 FLESH FOODS. THE FLESH OF WILD ANIMALS AND BIRDS. As -was mentioned before (p. 48), the flesh of wild animals differs from that of the animals included in the preceding class in its closer texture and in containing much less fat. But this distinc- tion is largely due to the different conditions under -which the animals live. The kind of food given to an animal has a considerable influence on the flavour of the flesh. Where fish has been the chief food the flesh acquires a fishy taste, and there is a marked difference in the flavour of a wild and tame duck. The following are some of the principal average results of the analyses of the flesh of animals in the group. They are taken from the long table given by Konig '* : — Per Cent. Per Cent. Calculated on the Dry Substance. ■Water. Nitrogenous Substances. Fat. N.-tree Extractives. Ash. Nitrogenous Substances. Tat. Nitrogen. Hare, . . Rabbit, . . Deer, . . Hen (lean), „ (fat) . Duck (wild), Goose (fat). Pigeon, . . 74-16 66-85 75-76 76-22 70-06 70-82 38-02 75-10 23-34 21-47 19-77 17-72 18-49 22-65 15-91 22-14 1-13 9-76 1-92 1-42 9-34 3-11 45-59 1-00 0-19 0-75 1-42 1-27 1-20 2-33 0'76 1-18 1-17 1-13 1-37 0-91 1-09 0-48 1-00 90-34 64-77 81-86 82-93 61-76 77-59 88-02 89-58 4-37 29-74 7-92 5-97 31-19 10-62 73-55 4-17 14-46 10-84 13-10 11-25 9-88 12-92 4-11 14-23 Schlossberger and von Bibra obtained the subjoined results (see Table, page 61). Bear's Flesh. — Strohmerf gives the following as the percentage composition of bear's flesh : — Water, 65-14 ; nitrogenous sub- stances, 26-37; fat, 5-41; and ash, 1-44. The Fat. — With one or two exceptions, the fat of the animals referred to in the preceding table has been but little examined, and in many cases the constants have been determined only with the fat of one individual. The most complete research on this point is that of Amthor and Zink, \ who have determined all the usual constants of the fat of a large number of animals and birds. They found that as a rule * Loc. cit., ii. p. 118. t Die Ernahrung des Menschen, J Abst. Analyst, 1897, p. 75. WILD ANIMALS AND BIKDS. 61 a high specific gravity of the fat was accompanied by a high melting point and low iodine value. The iodine value of the fats and fatty acids decreased on keeping, whilst, on the other hand, in the case of many fats, such as that of the stag, dog, and wild boar, the acid value increased. The iodine value and, gene- rally, the acetyl value* were lower in the fat of domestic animals than in that of the corresponding wild animals. A similar differ- ence was observed in the case of the birds, the fat of the domestic goose, hen, and duck being lard-like, while that of the related wild birds was oily. In four cases the fats had marked drying pro- Flesh of Water. Nitrogenous Substances. Albumin. Flesh Fibre. Gelatin- yielding. Roe, .... Do Hen, .... Wild Duck, Pigeon, 74-63 78-30 77-30 71-76 76-00 1-94 2 30 3-00 2-68 4-50 16-81 18-00 16-50 17-68 17-00 0-50 l'-20 1-23 1-50 perties, three of them becoming quite solid in the course of seven or eight to twelve days when spread in a thin layer on a glass plate. This property was possessed by the fat of the hare, wild rabbit, wild boar, and, in a lesser degree, by that of the blackcock. The fat of the wild boar differed from common lard in having a higher specific gravity, iodine value, and acetyl number, and especially in the above-mentioned drying property. Fox fat differed from that of the cat and dog in its higher iodine value and specific gravity, but more particularly in its high acetyl value.* The principal differences in the fats of the common and wild cats were the higher Eeichert and acetyl numbers and the considerably higher acid values of the latter. Pole-cat fat was quite liquid and had somewhat lower constants than the fat of the marten. The fat of the dog and cat were very similar in appearance to lard, which they also resembled in analytical constants, with the exception of the acetyl value, which was higher. Of the different bird-fats examined, that of the blackcock was noticeable for its drying properties and high iodine value. When spread on glass it soon set to a varnish, which, however, still re- * But cf. note, p. 58 (t). 62 FLESH FOODS. mained sticky. After fourteen days drying was still proceeding. After ninety-five days the iodine value had fallen to 29 '7. The chemical and physical constants of the fat of some of the principal animals of this group, which are used for food, are shown in the subjoined table (page 63). The ' Ripe7iing ' of Game. — When game is allowed to hang for some time in a whole condition the flesh undergoes an alteration which Eber considered was of a purely chemical nature, although he termed it ' acid fermentation.' The reaction of the flesh becomes strongly acid, the muscular tissue becomes more tender, and after some time traces of hydrogen sulphide are liberated. Eber found that the production of the characteristic iiavours of game stood in direct proportion to the amount of hydrogen sulphide or mer- captans set free ; but in his opinion the flavour (Iiaut goiet) was in no way due to the formation of putrefactive compounds. A similar ripening process can be brought about in the flesh of other animals besides game, and indeed is necessary in the case of old cattle, or of bulls. As apparently Eber did not make a bacteriological examination of the flesh before and after 'ripening,' his view appears unlikely to be correct, and it is far more probable that the change is brought about by certain species of bacteria. T?te ' Seating ' of Game. — When game is packed too closely and subjected to too high a temperature, an alteration rapidly takes place, which is probably, in the main, a chemical change, brought aboiit by bacterial products rather than by the bacteria themselves. Within an hour or two the skin becomes green, the hair loose and easily removed, and the muscle soft and flabby, while bubbles of gas may often be observed within the tissue. The reaction of the flesh is very acid, and considerable quantities of hydrogen sulphide are evolved, so that the flesh has a dis- agreeable odour. Eber* succeeded in imitating the green coloration and acid for- mation by injecting milk of potassium sulphide (0'5 per cent.). The origin, however, of the excess of sulphur compounds in the natural ' heating ' is doubtful, though it is probably due to the rapid permeation of bacterial products from the large intestine. That the alteration is not an ordinary putrefactive process is shown by the facts that no ammonia is produced, and that the change is not progressive, i.e. on removing the causes (the close packing and high temperature) the muscle retains for a consider- able period its consistency and original structure. This condition of the flesh may also occur in the flesh of other * Zeit.f. Fleiscli u. Milch Hyg., 1897, vii. p. 208. WILD ANIMALS AND BIRDS. 63 °9 O S 3 5.9 w> SSBW cf Mo Ga Oi o W ^ (M IN OS o o> (N i-t 64 CD .H O Tt"? Tl" OJ CO coeo „ OO 00 tM_ ^ tM ff~ ^ -*^ 2 ci 4. «!> :T 04 CO CO o in ■* «i> : CC ^ CO ^ CI CI en ■• o o o tH C^ _^ 00 O •* N O CO -M i a ":r .fe. •s 64 FLESH FOODS. animals from which the skin has not been removed in the summer. Eber has frequently observed it in the case of horses. According to Fischoeder,* ' heated ' flesh is not allowed to be sold in Germany, although no ill results have been traced with certainty to its use. THE FLESH OF VEKTEBRATE FISH. The muscular tissue of fish is generally white, and is less con- sistent than that of land animals. The difference in colour is due to the flesh and the blood retained by it containing so much less haemoglobin. In certain fish, however, such as the salmon, the flesh has a delicate pink tint which Krukenberg attributes to the presence of a colouring matter of the nature of a lipo- chrome. The flesh of fish usually contains a high percentage of water, often as much as from 80 to 85 per cent.; the amount of mineral matter is also usually high, sometimes amounting to nearly 2 per cent. In certain fish special constituents have been found, as, for instance, isokreatinine in the haddock (c/. p. 10). Fish undergo decomposition with extreme readiness, and in many cases the products of decomposition are deadly poisons to the human system. Occasionally, too, the living fish elaborate poisonous substances. These may be of the nature of leucomaines or albuminous toxines, and are probably in some instances due to the condition of the water in which the fish have been living.! The age of carp may be approximately estimated in the follow- ing manner : — A scale from the side of the fish is cleansed with alcohol and held to the light. If only a bright central spot is visible the carp is only one year old. If one ring surrounds the central point the fish is two years old ; if two rings, three years old, and so on. Experiments have shown that the number of rings regularly increases with the age. J The Fat of Fish.— It is mainly to the presence of certain constituents in the fat that the characteristic flavour of different kinds of fish is due. In some fish the liver is the chief source of the fat, as, for instance, in the case of the cod and shark, while the rest of the body contains only a small proportion. In other fish the oil is distributed throughout the body, and is not specially abundant in the liver. The fat is of an oily nature, and as a rule contains a smaller proportion of the compounds of the solid fatty acids than does the * Leitfaden der prak. Fleischheschau, 1897, p. 199. t Cf. pp. 219-222. t Zeit. Fleisch u. Milch Byg., 1897, p. 244. COMPOSITION OF FISH. 65 o I o hn a :o M a o * -a Tl ya =4H ■M O T3 ,y s fl ;3 [f 6J0 O cC a j» "D ^ (11 c3 ,ja 6r rl o n .OlO eoir-»OTtir- iHiHrHT-trH ^^ ti •s OOOeOCD-* ^ ,a ^ .S . . . .. H • • N River Eel Herring (i Mackerel Perch, Salmon, 66 FLESH FOODS. xn Eh o o o <1 * CO i-l 00 CI M o 0!;3 ^ HO =o.2,S'3d ogPn .° 5° i2 ^lO CO CO — -^m CO 3 "* ^ i CO -^ OO CO CO f-i CO CO l-\ I— ( I-t I— I CO CO O .M M -t^ *J Ift ^^ ^^ 0^ 1^ .( -i> Ti ail! ^^y^ COMPOSITION OF INVEETEBEATA. 67 fat of land animals.* It is mainly composed of glycerides of various unsaturated acids. The liver-oils usually contain certain bile products, which give rise to characteristic colour reactions with acids and alkalies. A considerable proportion of unsaponifiable matter, principally cholesterin, is also a usual constituent. "With the exception of cod-liver oil, the fish fats have been but little studied, and our knowledge of their physical and chemical characteristics is therefore limited. Hehner and Mitchell t have found that from marine animal oils — cod-liver, cod, shark, whale — compounds can be obtained which have many similarities with those prepared in the same way from linseed oil, though they have not the same drying capacity. For a full description of the nature of cod-liver oil and the methods of detecting its adulteration, reference must be made to works dealing specially with the examination of fats and oils. The previous table (page 66) gives some of the constants which have been obtained with fats of this class. THE FLESH OF INVEETEBRATE ANIMALS. The flesh of invertebrate animals does not present any marked difference in structure to that of other animals. In chemical com- position it diSers, as a rule, from that of vertebrate animals in con- taining more water, nitrogen-free extractives and ash, and less fat. According to Bolland, the acidity of Crustacea, calculated on the original substance, varies from 0'038 to 0-258 per cent. Konig I gives the following percentage composition of some of the members of this group : — Calculated on the Dry Substance. Water. Nitro- genous Sub- stances. Fat. N.-free Extrac- tives. Ash. Nitro- genous Sub- stances. Fat. Nitro- gen. Oyster, Flesh, 80-5 9-04 2-04 6-44 1-96 46-41 10-47 7-43 „ Liquid, . 95-76 1-42 0-03 0-70 2-09 33-49 0-71 5-36 ,, Flesh and Liquid, 87-30 5-95 1-15 3-57 2-03 46-85 9-06 7-50 Mussel, 84-16 8-69 1-12 4-12 1-91 54-86 7-07 8-78 Lobster, 81-84 14-49 1-84 0-12 1-71 79-80 10-13 12-77 Crab, . 79-97 15-80 1-64 0-75 1-94 78-87 7-69 12-62 * Excluding the liquid fats extracted from the feet, such as neatsfoot oil, etc. t Analyst, 1898, p. 317. J Loc. ciL, ii. p. 130. 68 FLESH FOODS. The foUoTving representative analyses are taken from A. Bolland's table * : — Nitro- genous Sub- stances. Drj' Substance. Water. Fat. N.-lree Extrac- tives. Ash. Nitro- genous Sub- stances. Fat. N.-free Extrac- tives. Asb. Crab, 76-5 16-89 0-87 5-75 0-99 67-60 3-69 24-50 4-21 Cockle, 92-0 4-16 0-29 2-32 1-23 52-00 3-67 29-00 15-33 Oyster, 80-5 8-70 1-43 7-33 2-04 44-60 7-32 37-61 10-47 Mussel, 82-2 11-25 1-21 4-04 1-30 63-20 6-82 22-68 7-30 Burgundy Snail, . 79-3 16-10 1-08 1-97 1-55 77-88 5-20 9-52 7-50 Weinberg Snail, . 80-5 16-34 1-88 0-45 1-33 83-78 7-10 2-32 6-80 A. Chatin and A. Muntz t have determined the amount of phos- phorus in different varieties of oysters. In 100 parts of the dry flesh they found 1-836 parts in French oysters, and 2"082 parts in Portuguese oysters. A Portuguese oyster of medium size con- tained 0-032 gramme, and a similar French oyster 0-02 gramme of phosphorus, which was present in combination with organic substances. Iron was also present. Green Oysters. — From the recent researches of Boyce and Herdman J there appear to be several kinds of greenness in oysters. In some varieties, such as the Marennes oysters and those from rivers on the Essex coast, the green colour is a normal and healthy condition, and is to be attributed to the presence of a pigment termed ' marennin ' and not to an excess of copper. This confirms Eay Lankester's conclusions, who found that the copper in green Marennes oysters was not greater than that normally present in the heemocyanin of the blood of colourless oysters. The average amount of copper found by Kohn in his analyses for Herdman and Boyce in different varieties (including those of Marennes) was 0'006 grain. In some kinds of greenness, however, there is undoubtedly a larger proportion of copper than this normal quantity. In certain American kinds, and in oysters from Falmouth, Herdman and Boyce found patches of green on the mantle and in the heart. * Comptes Bend., 1898, cxxvi. p. 1728. t Compt. Rend., 1895, p. 1095. t Proc. Hoy. Soc, 1897, Ixii. p. 30, and 1899, Ixiv.-p. 239. GKEEN OYSTEKS. 69 which were derived from an excess of copper in the blood leuco- cytes. This they attributed to a diseased condition of the blood which they term ' green leucocytis.' The quantity of copper in the green leucocytes varied considerably, some giving a marked brown coloration with potassium ferrocyanide, while others gave only a faint reaction. Occasionally iron was also fo.und. In the case of the Falmouth oysters, part of the excess of copper was mechanically attached to the body, probably as basic carbonate. Attempts to produce the greenness artificially by feeding oysters with dilute solutions of copper or iron salts were unsuccessful. CHAPTER IV. THE EXAMINATION OF FLESH. The absolute value of flesh as food, apart from the relative value which depends on the nature of the animal from which it was taken or its position in the animal, is largely based (1) on its physical external characteristics, such as colour, consistency, etc. ; (2) on the proportion of fat ; and (3) on its taste and odour. COLOUR The normal colour of sound flesh varies with its origin, ranging from white, as in the case of many fish, to dark purple-red, as in horse flesh. The colour being largely dependent on the amount of haemoglobin in the flesh, an approximate ratio may often be observed between the colour and the amount of iron (chiefly derived from the hsemoglobin) in the ash, left on calcining the flesh. Abnormal Colorations of Flesh. Melanosis. — Jlorot * describes a case in which the flesh of a calf three months old was found to contain numberless small black specks distributed throughout the body. Sometimes this is only local, and not, as in this instance, general. The black pig- ment is probably a derivative of htemoglobin. In Germany such flesh is sold at a low price by the Freibank (p. 215). White Flesli. — This is found normally in certain full-grown foreign animals. Occasionally it may happen that the flesh of a cow or ox does not acquire the usual amount of haemo- gloljiii and has the appearance of veal. Faucon f records a case of the kind in which the muscular tissue of a cow four years old had all the appearance of a calf's flesh, difl^ering only in the larger size of the muscular fibres and in its greater dryness. "White flesh is * Zeit. Fleisch u. Milch Hyg., 1898, p. 501. t Ibid., 1898, p. 34. ABNORMAL COLOUES IN FLESH. 71 found in certain diseases, such as the ansemia of dropsy, and is probably caused by an insufficient oxidation of the blood. Yellow Colour. — This is sometimes produced by the food given to the animal. In disease it is due to biliary compounds being absorbed and retained by the flesh. Brown Flesh (' Xantosis '). — An instance of this is described by Goltz, in which flesh had a brown coloration due to the presence of granules of a yellowish-brown pigment between the fibres. Dark Purple. — This may indicate that an animal has suffered from acute fever, and it is met with in animals that have died of rinderpest or tuberculosis. It may also be due to the animal having died a natural death, so that the blood has been retained in the body, or to insufficient bleeding after death, due to weak action of the heart. Dark Reddish-Brown. — This is due to imperfect oxidation of the blood. It is observed in the case of animals which have been drowned or sufibcated in smoke (COj poisoning). There is also often considerable discoloration in the flesh of animals which have been hunted or over-driven. Scarlet. — This is but seldom met with. It indicates carbon monoxide poisoning, and is sometimes a result of arsenic poisoning (Walley). Diffused Redness. — This is due to the diff'usion of hsemoglobin, and is often seen in meat which has been frozen. It is also found in cases of blood-poisoning. Iridescence. — This is a normal characteristic of horse flesh. In other animals it occurs as the result of certain diseases of the blood. Green or Violet Hue. — This may be due to the commencement of putrefaction, or to the diffusion of vegetable colouring matter through the membrane of the stomach after death (Walley). (See also Green Oysters, p. 68.) Colorations due to the Direct Action of Bacteria. These are referred to under the heading of 'Chromogenic Bacteria on Flesh,' p. 270. Artificial Coloration of Flesh. KeUermann* has recently detected saffron in a sample of so-called smoked pork. The connective tissue was very yellow, while the muscle had the colour of ordinary flesh. It had not the usual smell of smoked flesh. On treatment with alcohol an * Zeit.f. Vntersuch. Nahr. Genussm., 1898, p. 247. 72 FLESH FOODS. intensely yellow solution was obtained, which, on evaporation, left a residue giving a violet coloration with sulphuric acid. An account of the various substances used to colour sausages and meat preparations, and the means of detecting them, is given in a subsequent chapter.* The 'Flesh Juice' ('Eoseline') of Adamczyk, Berlin, consists of red carmine lake in ammoniacal water. UNSOUND FLESH. In this country the inspectors condemn the flesh of animals which have died from natural causes, or as the result of an accident, as well as of those which have suffered from certain diseases, such as pleuro-pneumonia, puerperal fever, etc. Meat which is tainted with chemical substances, such as phenol, or in a state of putre- faction, or infected with animal parasites, such as liver flukes or hydatids, is also obviously rejected. To distinguish the meat of diseased animals cannot, as yet, be done with any certainty by chemical methods, and it requires considerable practice to form a correct judgment of the character of flesh by its appearance. The bacteriological methods of examina- tion are described in Chap. XIII. General Characteristics of Soimd Flesh. — According to Letheby,t sound fresh meat has the following general charac- teristics: — 1. The colour is neither very pale nor dark purple. 2. It has a marbled appearance, due to the presence of small veins of fat distributed throughout the muscle. 3. It is firm and elastic to the touch, and not sodden or flabby, and scarcely moistens the finger. 4. It is free from objectionable odour. 5. It does not become wet on standing for a day or so, but, on the contrary, gets drier. 6. It does not lose more than 70 to 74 per cent, in weight when dried at 100° C, whereas bad meat often loses more than 80 per cent. 7. It does not shrink much in cooking. Chemical Tests for Unsound Flesh. Apart from alterations in the appearance of the parts locally affected with the disease, it is probable that chemical alterations also occur in the flesh through the products of the bacterial action permeating the muscular tissue of the living animal. So far the only attempt to difierentiate diseased from healthy flesh * Cf. p. 142. t On Foods, p. 210. EBEE'S HYDROGEN SULPHIDE TEST. 73 on these lines is that of Professor Eber, who was still working on the subject at the time of his death.* His test is based on the fact that in the case of diseased animals, especially those suffering from tuberculosis, there is often a considerable increase in the amount of readily decompos- able sulphur compounds in the flesh, which can be approxi- mately measured by noting the relative amount of hydrogen sulphide (or mercaptans) evolved on treating the flesh with dilute acid. Although hydrogen sulphide is often one of the products of putrefactive decomposition, its presence does not necessarily denote putrefaction. Thus traces of it are normally present in the free state in all old flesh, of which the reaction is still acid, and considerable quantities are evolved during the ' heating ' {'verhitzein') of game.f That the volatile sulphur products of pathogenic bacteria may be rapidly diffused throughout the body is shown by the fact that the carcasses of pigs killed on account of swine erysipelas turn green after the lapse of a very short time (thirty minutes), and emit an unpleasant ' odour ; and, as the flesh still has an acid reaction, putrefaction is here out of the question. The muscles, kidneys, and lymph-glands of healthy recently- killed animals evolve hydrogen sulphide when heated in a test- tube on the water-bath, the gas being probably derived from the decomposition of proteid matter ; but Eber could not notice any difference in the quantities thus yielded by healthy compared with diseased flesh. The more limited decomposition brought about by the action of dilute sulphuric acid gave more promising results, which Eber was intending to confirm and extend. Eber's Hydrogen Sulphide Test. J — From 10 to 25 grammes of the finely divided substance are mixed with 50 grammes of dilute sulphuric acid, (1 : 10) in an Erlenmeyer flask, in the neck of which is fixed, by means of a loose plug of cotton-wool, a strip of filter-paper previously soaked in a 10 per cent, solution of lead nitrate. The flask is kept in the dark for twenty-four hours in a spot to which there is free access of air, without a draught, at a temperature which may vary from 12° to 18° C, without influ- encing the results. At the end of the time the strip is gummed in a book, and after the lapse of thirty minutes compared with a standard scale of strips. * "W. Eber, bom 1863, died June 1898. t Of. p. 62. t Zeit. FUisch m. Milch Eyg., 1897, vii. pp. 207-211, 227-231 ; and vlii. pp. 41-46. 74 FLESH FOODS. The colour of the strip will vary from faint brown (rarely yellow) to black, the lower part being the most intense. The colour scale,* of which the relative shades are shown in the frontispiece, is an arbitrary one, and the absolute value of each colour was not definitely determined by Eber. Preliminary experiments, with a solution of potassium sulphide yielding an accurately determined amount of hydrogen sulphide, indicated that the lowest colour in the scale No. 1 corresponded to 0'002 milligramme of hydrogen sulphide, while No. 8 (black) was first attained with O'Ol milligramme. By this method Eber found that the mean results obtained with the flesh of different kinds of animals were, as a rule, some- what higher in oases of tuberculosis (viz., 4'6 as against 3'5), whilst the tests with the ileo-lumbar glands often showed a con- siderable difference, as is seen in the following figures : — i. Healthy, . . 130 samples. 100 negative, mean 0'2 ii. Local tuberculosis, 44 ,, 8 „ „ 1-6 iii. General tuberculosis, 36 „ 3 ,, „ 2'7 The results given by the kidneys were invariably high (6 to 7), and no difference could be found between those of healthy and of diseased animals. As these figures were obtained without the precaution of exclud- ing light, which, as was subsequently found, tends to lower the value, it was Eber's intention to repeat the tests. Much more work is required on the subject before this test can be regarded as having passed the experimental stage, but it indi- cates a starting-point for fresh departures, and has possible appli- cations in other directions. Thus it may be found to serve as a measure of the haut gout of game, f and may be employed to eluci- date the progress of the changes which occur in the putrefaction of flesh. The Ptomaines formed during Putrefaction. — The methods of isolating the basic alkaloidal products formed during the decomposition of flesh by saprophytic bacteria, and the charac- teristics of individual ptomaines, are described in Chap. XIV., p. 298. The Eeaction towards Litmus Paper. — A slice is out from the meat and pressed against a piece of moistened litmus paper. After ten minutes the paper is removed and compared, on a * The original colour scale may be obtained from R, Schbtz, Lnisenstrasse 36, Berlin, N.W. t Gf. p. 62. CHEMICAL TESTS FOE UNSOUND FLESH. 75 white surface, with a piece of the original litmus paper similarly moistened. As a general rule, flesh becomes acid soon after death, and con- tinues so until sufficient ammonia is produced during the progress of putrefaction to render it alkaline.* According to Augst,t in cases of acute pneumonia, or other diseases causing shortness of breath, the flesh only assumes the normal acid reaction some twenty-four hours after death, and is alkaline until then. Hartenstein J records a similar phenomenon in the case of a cow which had been killed after suffering for five days from colic. The flesh had a marked alkaline reaction four hours after death, and it was not until the next day that it became acid. Occasionally the result of the litmus test is a colour inter- mediate between the red and blue. This ' amphoteric ' reaction occurs most frequeiitly in the muscles of animals which have not been cut up, such as birds and fish. The alkaline reaction is also obtained with certain organs of the body in a fresh condition, as, for example, the spleen. Pickled flesh and smoked ham are also, as a rule, strongly alkaline. Eber's Test for Putrefaction. — To detect incipient putrefaction, Eber§ recommended the use of a reagent, composed of hydro- chloric acid, 1 part ; alcohol, 3 parts ; and ether, 1 part. A glass rod is moistened with this and brought near the meat, from which, if putrefaction has commenced, fumes of ammonium chloride are often produced. In order to avoid the chance of error, due to the fuming of the hydrochloric acid itself, a few c.c. of the reagent are introduced into a stoppered cylinder, which is shaken so as to moisten its sides, and a fragment of the meat introduced on the end of a wire. The intensity of the cloud of ammonium chloride is not pro- portional to the odour of the flesh, for in some instances putrefac- tion may proceed without the evolution of malodorous substances, and in others these may only become evident on boiling the flesh. This is noticeable in the case of salt fish, in which there may possibly be a combination between the volatile bad-smelling com- pounds and the salt. Sometimes Eber's reagent gives negative results when putre- faction has commenced, owing to the formation of acid substances, instead of or in excess of the ammonia. This is especially the case with liver and with game. * Cf. p. 19. t BeuUch. Tieriirzt. Wochensch., 1897, p. 37. t Zeit. Fleischu. Milch Eyg., 1898, p. 68. § lArch. Wissensch.il,. prak. Thierheilk., 1893, xviii.,and 1894, xix. p. 81. 76 FLESH FOODS. Eber classified the results of this test in the following scheme : — I. No cloud of NH^Cl (absence of ordinary (alkaline) putrefaction). rAcid "\ Reaction of\ . ', , ■ \(a) with bad odour, /««^. ifrr '((Vwithout „ / i.withH,S. Ulkalme, JW » | h. without h^S. II. Cloud (Putrefaction proper). Reaction 0/ a {. ^ ■ \(a) with bad odour, /e«^, liiT^i '^without „ / i.withH,S. ■> ' Ulkalme, JW .. | ji. without H2S. TEEATMENT OF MEAT WITH ANTISEPTICS. It is no uncommon practice for butchers to treat meat which has been kept too long with various chemical solutions in order to retard or disguise the commencement of decomposition. Of these reagents the least objectionable is a dilute solution of potassium permanganate, which removes the odour from meat slightly tainted on the surface, but is incapable of disguising deep- seated decomposition. Many of the preservative solutions contain calcium or sodium sulphites or bisulphites as a chief constituent. The salts of sul- phurous acid have not only an antiseptic action, but possess the property of restoring the colour of flesh which has become brown or grey through exposure to the air. The action of sulphurous acid on the meat fibres, and the methods of detecting it, are referred to on p. 121. Borax and boric acid are also frequently used for this purpose. L. Baillet * records the results of experiments in which joints of mutton were steeped for a month in a solution of borax. The meat had nearly its normal red aspect, but the borax had pene- trated a long way into the flesh, and could readily be detected by turmeric paper (see also p. 119). According to de Cyon of St Petersburg, meat treated with a solu- tion of boric acid acquires a disagreeable appearance and flavour. The use of salicylic acid or formaldehyde, which are said to be employed for ' doctoring ' meat, cannot be very general on account of their other effects (pp. 122-123). As meat which has thus been treated is often in a state of arrested decomposition, the following tests will often be service- able in detecting the fraud. * TraiU de I'Inspection des Kiandes, p. 523. 124), 'BLOWN meat' — CONSISTENCY OF FLESH. 77 1. General appearance and physical characteristics, such as excess of moisture and want of firmness ; meat which has been kept too long readily tears, and does not cut evenly. 2. The appearance and acid value of the fat (c/. p. 95). 3. The reaction of the meat-juice towards litmus and turmeric paper (p. 74). 4. The microscopical appearance of the fibres (p. 117). 5. The chemical identification of definite preservatives (pp. 118- ' BLOWN' MEAT. With the object of imparting a better appearance, meat is some- times ' blown ' by butchers. This process consists in inflating the loose cellular tissue by means of bellows, or usually with the breath through a blow-pipe, and then blowing melted fat over the parts. In Germany this disgusting practice is common in the case of calves and sheep, but is less frequently met with in beef.* In this country, according to 0. Andrews, veal and lamb are occasion- ally 'blown.' The blown-out parts appear larger, and have a shiny surface, while the muscle feels spongy and crackles under the pressure of the finger. Small air-bubbles may frequently be observed within the tissue. Lungs which have thus been ' blown ' have rounded edges, and contain isolated air-bubbles. CONSISTENCY OF FLESH. The consistency of meat is a valuable criterion of its soundness. Good meat is firm to the touch, while unsound flesh is frequently flabby and exudes moisture. Coarse-grained meat, which cannot be cut evenly and regularly, is inferior to fine-grained. The nature of ' grain ' depends (1) On the age of the animal, the fibres being finer in the case of young animals ; (2) On the race of animals and nature of their feeding ; and (3) On the sex of the animal — the cow, for example, having flesh of finer fibre than the bull. Determination of the Degree of Toughness. — Lehmann t has devised an ingenious apparatus for determining the degree of tough- ness of different food products. This consists of a balance with arms of different lengths, the shorter being constructed on the principle of a 'pair of scissors with one of the blades fixed. The weights are placed in the pan of the longer arm, and the force required to cut through a layer of the substance 1 cm. thick is expressed in grammes. * Fischoeder. t Zeit. Fleish u. Milch Hyg., 1898, viii. pp. 32-33. 78 FLESH FOODS. With this apparatus Lehmann found that the skin muscle of beef is two and a half times as tough as the fillet, owing to the greater proportion of the white (collagenous) fibres of connective tissue in the former, and of elastic fibres in the latter. Colla- genous fibres (sinews) required 1040 grammes, whilst elastic tissue required only 580 grammes for complete division. Hence, flesh which contains much collagenous tissue becomes more tender on boiling, whereas that containing but little remains practically the same. For instance : — Fillet of beef, . . . . Skin muscle of beef {HautmuskeT), The following values were also obtained body in the raw and cooked state : — Heart, Tongue (Hyoglossus), Liver, ox, . ,, calf, Kidneys, Brain, It is interesting to note that game, on hanging, loses in a few days 25 per cent, of its toughness. Kaw, Boiled, rammes. 83-4 grammes. 84-0 236-4 88-8 different parts of t Kaw, Boiled, grammes. 104 grammes 88 . . • 64 42 8 35 6-6 40 24 7-0 2-4 THE ODOUE OF FLESH. This is best observed on boiling fragments of the flesh with water, and in some cases by mixing the flesh with dilute sulphuric acid, distilling about a fourth part of the liquid, and noting the smell of the distillate. It may be : — (i.) The normal odour characteristic of each kind of animal. (ii.) The characteristic odour intensified to a very unpleasant extent, in the case of the flesh of uncastrated male animals. This is more marked with the flesh of the he-goat and boar than with that of the ram and bull. (iii.) An abnormal odour, due to the substances (fish, for example) eaten by the animal, (iv.) An odour due to chemical alteration or decomposition, as, for instance, that of the volatile products formed during the ' heating ' of game, or the putrefaction of flesh, (v.) An odour of foreign substances — phenol, chloride of lime, etc. DETERMINATION OF WATER AND ASH. 79 ANALYTICAL METHODS. Determination of Water. — From 5 to 10 grammes of the finely divided flesh are dried in an air bath maintained at 105°-110° C. until the weight is constant. If the substance is readily oxidizable it must be dried in vacuo, or approximate results may be rapidly obtained by the following method, used by C. Parsons * for sensitive organic bodies, in which the action of atmospheric oxygen is excluded during the drying : — A neutral mineral oil with a high flash test and boiling point is heated at 250° F. imtil its weight becomes constant. A basin con- taining some of the oil is weighed, heated at 240° F. for some minutes, a few thin pieces of the meat (previously weighed) added, and the heating continued until all effervescence ceases. The loss in weight of the basin containing the oil and the meat gives the amount of water expelled. Abnormal Moisture. — Walley t gives a summary of the various causes leading to an excess of water in flesh. These are (1) Albu- minous effusion, as in 'turnip braxy' in sheep (c/. p. 53), due to enzymic action in the cells of the living animal ; (2) Effusion of serum or hydrasmia, as in the ' water-braxy ' of sheep. This is also found in diseases with inflammatory symptoms, such as erysipelas, and may originate from irritation set up by parasites (cysticerci). Effusion of serum occurs in mea»t which has been thawed after freezing. (3) Lymph effusion, either local or diffused, arising from inflammation or other disease. (4) Effusion of blood, either local or general, caused by violence or disease. (5) Effusion of urine, which is necessarily local. Determination of Mineral Matter (Ash). — The residue left from the determination of water is ignited in a covered platinum dish, preferably in a muffle-furnace. Iron, Calcium, and Magnesium. — The ash is dissolved in dilute hydrochloric acid, and the iron precipitated with ammonium acetate, the calcium with ammonium oxalate, and the magnesium with sodium phosphate. Sodium and Potassium. — Warden and Bose % determine these metals in the following manner : — The soluble ash is dissolved in water, barium chloride, ammonium chloride, and ammonia added, and the liquid heated and filtered. The filtrate is mixed with ammoniimi carbonate and ammonium oxalate, heated and filtered. The filtrate and washings are evaporated to dryness, the ammonium salts removed by gentle ignition, water added to the residue, and the insoluble matter filtered off. The filtrate is mixed with a few * Journ. Amer. Chem. Soc, 1897, p. 388. t Loc. at., p. 33. J Chem. News, 1890, Ixi. p. 291. 80 FLESH FOODS. drops of hydroclilorio acid, and evaporated to dryness with an excess of platinum chloride. The residue of double chlorides thus obtained is treated with alcohol in the usual manner, but the insoluble potassium compound, instead of being weighed, is ignited at a low temperature, the residue exhausted with boiling water, and the resulting solution of potassium chloride titrated with standard silver nitrate. The alcoholic solution containing the excess of platinum chloride and the platinum sodium chloride is evaporated to dryness in a platinum basin, sufficient ammonium chloride solution added to combine with all the platinum, the mixture evaporated to dryness, and the residue cautiously ignited. The final residue is extracted with hot water, and this solution also titrated with silver nitrate. From the results of the two titrations the respective amounts of potassium and sodium are calculated. Estimation of Sulphur. — The finely divided flesh is placed in a large silver or nickel dish, and covered with about twice its weight of sodium carbonate, on which is laid a piece of sodium hydroxide about half the weight of the carbonate. The dish is moved slowly over a small flame until all evolution of gas has ceased, and a half fused mass is obtained. Finely powdered sodium peroxide is then dusted over in successive small quantities imtil the carbon has been completely burned away. When cold the mass is treated with water, the solution filtered, hydrochloric acid containing bromine added, and the liquid boiled until free from odour. The sulphate is then precipitated with barium chloride in the usual manner.* Estimation of Chlorine. — A weighed quantity of the flesh is calcined with calcium nitrate, the residue dissolved in hot dilute nitric acid, and the chlorine determined either gravimetrically or volumetrically. Estimation of Phosphoric Acid. — J. Katz t lays stress on the importance of determining the amount of this constituent. He states that the phosphoric acid which can be extracted from the flesh with water belongs to the phosphates, whilst that obtained from substances soluble in alcohol is a constituent of the lecithin. The substances insoluble in both solvents contain the phosphorus of the nucleins (see p. 21). Estimation of the Total Nitrogen.— rThe total nitrogen may be determined either by combustion with soda-lime, or, more readily, by modifications of Kjeldahl's process. In ordinary cases correct results are obtained by the Gunning * A. von Asboth, Ohem. Zeit., 1895, xx. p. 2040 ; C. Glaser, Journ, Amer. Chem. Soc, 1898, xx. p. 130. t ArcMv. ges. Fhys., Ixiii. p. 1. KSTIMATION OF SOLUBLE CONSTITUENTS. 81 modification, in which the substance is oxidized with boiling sul- phuric acid, to which potassium bisulphate and a drop of metallic mercury are added after frothing has ceased. When, however, nitrates are present in any quantity, as in the case of meat which has been pickled in a solution containing nitre, lodlbauer's modification should be employed. In this 2 grammes of salicylic acid (or phenol) are previously dissolved in the sul- phuric acid, and 1 or 2 grammes of zinc dust and a little mercury introduced into the flask before the heat is applied. Dyer* recommends the rapid introduction of the oxidizing agents, in order to avoid loss through the formation of lower oxides of nitrogen. Kivifere and Bailhache t made experiments with various sub- stances with the object of shortening the time required for the oxidation. They found sodium pyrophosphate, prepared by calcining the ordinary phosphate, the most suitable substance for raising the temperature of the sulphuric acid and accelerating its action. At the same time a much smaller quantity (2 grammes) was requited than in the case of potassium bisulphate. The com- parative table published in the original paper shows that this modification gives accurate results with horn, dried blood, and flesh. The Soluble Extract and Eesidual Muscular Fibre. — Konig adopts the following method of determining the soluble substances in flesh : — About 50 grammes of the flesh, freed as completely as possible from fat, are repeatedly extracted with cold water, the united extracts filtered, the filtrate made up to definite volume, and aliquot portions taken for the subjoined estimations : — (i.) Total Soluble Matter. — An aliquot portion is evaporated in a platinum basin and dried at 100°-105° C. (ii.) Ash. — The residue left on evaporation of the water is ignited in a covered platinum basin and weighed. About 94 per cent, of the total mineral matter in the flesh goes into solution. (iii.) Total Soluble Nitrogen. — An aliquot portion is evaporated in a tinfoil basin, the residue (with the tin-foil) intro- duced into a Kjeldahl flask, and the nitrogen determined in the usual way. (iv.) Soluble Albumin. — An aliquot portion is boiled, the coagulated albumin filtered off, and the amount of nitrogen remaining in the filtrate determined and de- ducted from the total nitrogen. The difierence, multi- plied by 6"3, gives the quantity of albumin. * Analyst, 1895, p. 242. t Bull. Soc. Chim., 1896, xvi. pp. 806-811 : Analyst, 1396, p. 267. F 82 FLESH FOODS. Collagene. — On treating flesh witlt boiling water instead of cold, or at 40° C, no albumin is dissolved, but gelatin derived from the connective tissue passes into solution. A weighed quantity of the flesh is first extracted with cold water, as above, and then with boiling water, which dissolves the collagene, leaving behind the fat and fibre. The amount of collagene is determined by evaporating an aliquot part of the hot water extract and drying the residue at 100°-105°. Muscular Fibre. — The residue left from the successive cold and hot water extractions is collected on counterpoised filter-papers, washed with hot water, then with warm alcohol, to remove the water, and finally extracted with ether, which removes nearly all the fat. It is then dried at 105°-110° C. and weighed. The amount of the constituents of flesh soluble in water varies between 4 and 8 per cent., the mean, including albumin and gelatin, being from 6 to 6'.5 per cent. Substances Soluble in Alcohol. — The amount of these is deter- mined in the same manner as the aqueous extract. According to Konig they consist of flesh bases, non-nitrogenous extractives and salts, and vary in quantity from 1'5 to 3 per cent., the mean being about 2 per cent. The strength of the alcohol used is 80-90 per cent. Nature of the Soluble Nitrogenous Substances.— Salkowski* treats the flesh with water at a temperature not exceeding 30° C, in order to prevent as completely as possible the gelatin dis- solving. He finds that under these circumstances 22-6 per cent, of the total nitrogen of the flesh is dissolved, the solution con- taining coagulable albumin, albumoses, peptones, the flesh bases, and Siegfried's carno-phosphorio acid. Determination of Phospho-Camic Acid.t — After precipitating the phosphoric acid from the extract by means of calcium chloride and ammonium hydroxide, the carno-phosphoric acid is precipitated with ferric chloride. The precipitate, which also contains some ferric hydroxide, is dried, and the nitrogen it contains deter- mined by Kjeldahl's process. The quantity of nitrogen multiplied by 6"124 gives the carno-phosphoric acid. Detenniaation of the Amide Nitrogen. — Of the numerous methods which have been proposed for the estimation of amide nitrogen in the presence of proteids, J, W. Mallet J has found precipitation of the proteids, with phosphotungstic acid supple- mented in some cases by precipitation with tannin, to give the most satisfactory results. * Forschungs Berichte, 1897, p. 22. t Balke and Ide, Zeit. Physiol. , 1896, p. 330. J Bull. 54, U.S.A. Department of Agriculture, abst. Analyst, 1899, p. 328. DETEEMINATION OF AMIDE NITROGEN AND FAT. 83 For the analysis of raw or cooked meat he triturates a weighed quantity with sharp-edged sand (previously ignited) or with hard- glass, so as to thoroughly subdivide the tissue. Two aliquot parts of this pulp are taken, of which one is used for the deter- mination of the total nitrogen. The other is digested with cold water (to avoid formation of gelatin) so long as soluble matter is removed to any extent. By this treatment kreatinine and sar- cosine are readily dissolved ; kreatine fairly readily ; but xanthine, hypoxanthine (1 : 300) and carnine (1 :312) are less soluble. The filtrate is rendered slightly acid with acetic acid, heated to about 99° C, and filtered from any precipitate. An acidified solution of phosphotungstic acid is added to this filtrate so long as a precipitate results, any large excess being avoided. A little powdered glass or sand is then added, the contents of the beaker heated to about 90° C, and filtered, and the precipitate washed with water, also at. about 90° C. Assuming that only proteid and amide nitrogen are now present, the former is determined by Kjeldahl's method in the precipitates and deducted from the total nitrogen previously determined. When peptones are present they are incompletely precipitated by phosphotungstic acid, and the solution should therefore be treated with tannic acid (5 to 10 per cent, solution) and filtered before the addition of the phosphotungstic acid, the nitrogen of the precipitate being estimated and added to the proteid nitrogen. As factors for the conversion of the nitrogen found in the proximate constituents, Mallet prefers the following : — For proteids and allied substances, multiply the nitrogen by 6-25. For flesh bases and simpler amides of animal origin, multiply by 3*05. For simple amides and amido acids of vegetable origin, multiply by 5'15. For mixed amido-constituents of unabsorbed solid residues in digestion experiments, multiply by 9 '45. The solution of phosphotungstic acid used is a 5 to 10 per cent, solution in 2 '5 per cent, hydrochloric acid. Estimatioa of the Pat. — After removing all visible fat from flesh, the muscular tissue still contains a considerable proportion, which it is not easy to extract completely. Dormayer * shows that even after extracting dried and powdered flesh for five months with ether, fat is still retained by the tissue. He recommends digesting the flesh with an acid solution of pepsin, and extracting the fat with ether from the solution thus obtained. * Vierteljahrsch. f. Nahr. u. Genussm., 1895, p. 325. 84 FLESH FOODS. 0. Fronlie " steeps 20 grammes of the finely-divided flesh in 100 CO. of 96 per cent, alcohol for twenty-four hours, with frequent stirring. The alcohol is then drained off, and the treatment repeated twice or thrice with the same quantity of absolute alcohol, and then twice with ether. The residue, freed from ether On the water-bath, is finely powdered and extracted for twenty- four hours, first with ether, and then with petroleum spirit (b. p. 60° C). E. Voit t gives a simpler method. 100 grammes of the finely- divided flesh are mixed with sufficient alcohol to form a pasty mass, which is dried, with frequent stirring, on the water-bath, in which the water is kept below 80° C. About fifteen hours are required for this. The dried substance is then powdered and passed through a sieve, with a mesh of 0"4 mm. Four grammes of the flesh thus prepared are dried at 70° C. for twelve hours and extracted with ether for twenty-four hours in a Soxhlet apparatus. The crude fat is dissolved in petroleum spirit, the solution filtered and evaporated, and the residue weighed. The flesh after extraction, tested by Dormayer's digestion method, still contains from 0"59 to 1'7 per cent, of fat, but Voit affirms that the fat obtained by continuing the digestion for longer than twenty-four hours is much less pure, and that the final product of Dormayer's method is also very impure. A rapid process has recently been described by Liebermann and &:e]cely. X Five grammes of the minced flesh are boiled for thirty minutes with 30 c.c. of a 50 per cent, solution of potassium hydroxide (sp. gr. 1"54) in a flask of the following description:- — The body is 7"5 cm. in diameter and 5'5 cm. deep, and has a flat bottom. The neck is 19'5 cm. long and .3 '5 cm. in diameter throughout its length. When filled to about the middle of tlie neck the flasli holds about 290 c.c, and has a mark at 240 c.c. After the boiling the contents of the flask are cooled, mixed with 30 c.c. of 90 to 94 per cent, alcohol, and again heated for about ten minutes. When cold, 100 c.c. of 20 per cent, sulphuric acid (sp. gr. ri45) are cautiously added, with constant shaking and continual cooling, in order to avoid a possible loss of volatile fatty acids. The liquid, which finally contains an excess of about 4 '4 grammes of sulphuric acid, is mixed with 50 c.c. of petroleum spirit (sp. gr. 0'6 to 0'7 and boiling-point about 60° C), and the flask closed with a rubber cork, and shaken about thirty times at intervals of one or two minutes. A saturated solution of sodium chloride is then added, so that the flask is filled to about * ZeU.f. Biol, 1897, pp. 549-554. t Zeit. f. Biol., 1897, pp. 555-582. J Chem. Zeit. Eep., 1898, xxii. p. 288, KSTIMATION OF FAT — DIGESTIBILITY. 85 the middle of the neck, whilst the aqueous layer below the petro- leum spirit stands at the mark (240 c.c). After again being shaken once or twice the closed flask is placed in a vessel of water and allowed to stand at not too high a temperature. As soon as the petroleum layer (which now con- tains the entire fatty acids in solution) has separated, 20 c.c. are pipetted off into a wide-necked flask of about 150 c.c. capacity, mixed with about 40 c.c. of neutral 96 per cent, alcohol, and titrated with decinormal alcoholic potassium hydroxide. The titrated liquid is then transferred to a weighed glass basin, holding about 80 c.c, and provided with a ground glass cover, in which it is cautiously evaporated to dryness on the water-bath at a low temperature, and finally dried for an hour at 100° C, and weighed. In order to calculate the amount of fat, the potassium in the soap must be deducted and the equivalent amount of glycerin radicle added. One c.c. of decinormal potassium hydroxide = 0'00391 gramme of potassium and 0"00136 of (C3H5), so that one must subtract as many times 0'00255 gramme as the number of c.c. of alkali used in the titration. The quantity of fat in the flesh can thus be calculated by the formula : — ^ p- 0-01- (Zx 0-00255) 1 250 in which F is the percentage of fat required ; S the weight of potassium soap from 20 c.c. of the petroleum spirit; K the number of c.c. of decinormal potassium hydroxide ; and a the weight of the substance under examination. According to 0. Polimanti * the following simple method gives practically the same results as the Dormayer digestion process. Two grammes of the powdered flesh are shaken for six hours with 200 c.c. of ether and 2 c.c. of metallic mercury, and the fat deter- mined in an aliquot portion of the filtered extract. THE DIGESTIBILITY OF DIFFERENT KINDS OF FLESH. As the conditions which exist in artificial digestion experiments are very difi'erent from those of the natural process it is not wise to base too general conclusions on the results of such experiments. Nevertheless, they may often furnish valuable information as to the behaviour of flesh under the influence of one or more of the * FflUger ArcUv, 1898, Ixx. 366. 86 FLESH FOODS. many factors which go to form the physiological processes which we term digestion. Artificial Peptic Digestion Experiments. — A simple method of obtaining the gastric juice for such determinations is to cut the fresh mucous membrane of a pig's stomach into small pieces, and to mix the fragments with 5 litres of water and 100 c.c. of 10 per cent, hydrochloric acid. After adding a small quantity of an alcoholic solution of thymol as a preservative, the mixture is left for twenty-four hours, with occasional agitation, and is then filtered, first through flannel, and then through paper. Finally the degree of acidity is determined and brought to exactly 0'2 per cent. As thus obtained the solution of gastric juice can be kept unchanged for months. One of the dried pepsins in the market may be used instead of the freshly prepared gastric juice in the proportion of about 0'5 gramme to 100 c.c. of dilute hydrochloric acid (0-2 per cent.). Five grammes of the lean meat, iu as fine a state of division as possible, are mixed in a flask with 500 c.c. of the artificial gastric juice, and the flask immersed in a water-bath maintained at a constant temperature of 40° C. for three hours. The portion remaining undissolved is then collected on a filter, washed, dried, and weighed, an allowance being made for the amount of water contained in the original flesh. Artificial Pancreatic Digestion Experiments. — For the pre- paration of artificial pancreatic juice a portion of the pancreas of an ox may be well triturated with sand in a mortar, and extracted with cold water, or with a 2 per cent, solution of sodium carbonate. ThjTuol should be added to the extract as a preservative, as in the case of artificial gastric juice. The digestion experiments are made in the same way as those with pepsin, but the liquid instead of being acid should be slightly alkaline (1 per cent, of sodium carbonate). The products formed by the action of pepsin and trypsin on the proteids of flesh are referred to in a subsequent chapter (p. 179). Comparative Digestibility of Flesh. — Chittenden and Cummins * have determined the relative digestibility of different kinds of flesh by pepsin. In each case 20 grammes of the sample were freed as completely as possible from sinew, fat, skin, and bone, and treated with 5 grammes of pepsin dissolved in a litre of hydrochloric acid (0-2 per cent.). The amount of cooked beef digested was 4'0461 grammes, and this was taken as the standard. Representing this amount as 100, the relative digestibility in * Amer. Chem. Journ., vi. p. 318. AETIFICIAL AND NATURAL DIGESTION. 87 94-89 Mackerel, . 86-24 92-15 Herring, . . 82-34 87-93 SheU-fish, . 82-5 86-72 Eel, . . 71-76 84-42 Lobster (female). . 79-06 92-29 ,, (male). . 69-0 87-03 Crab, , 67-13 72-39 Frog's leg, . 80-40 artificial gastric juice of other kinds of flesh under the same conditions were : — Veal, Mutton, . Lamb, Hen (light , , (dark Salmon, , Trout, . Cod, The digestibility of raw beef as compared with cooked beef was as 142-38 is to 100. Physiological Experiments. — In addition to artificial digestion experiments many physiological experiments have been made on animals and human beings, weighed quantities of flesh or other food being given, and the amount and nature of the excreta determined, the difiierence being regarded as digested. Thus, in 1862, Eanke showed that in a feeding experiment in which 18-32 grammes of beef were given, 11-5 per cent, of the total nitrogen was found in the waste products. W. Atwater * made experiments on these lines to determine the digestibility of shell-fish in comparison with beef. Of the former about 155(3 grammes, and of the latter about 1200 grammes, were eaten by a young man, together with a certain proportion of butter, salt, and spice. The results thus obtained were : — Absorbed. Separated in Excreta, Dry Sub- stance. Nitro- genous Matter. Fat. Salts. Dry Sub- stance. Nitro- genous Matter. Fat. Salts. Fish, . Beef, . 95-1 95-7 98-0 97-5 91-0 94-8 77-5 78-5 4-9 4-3 2-0 2-5 9-0 5-2 22-5 21-5 From these it follows that, in the case of this individual at least, shell-fish is as digestible as beef, and this conclusion received confirmation in similar experiments on a dog. But since the amount of a given food which is capable of being absorbed into the system varies considerably in the case of difierent * Zeit. f. Biol., 1887, xxvii. p. 215. 88 FLESH FOODS'. individuals, a conclusion as to the absolute degree of digestibility can only be drawn from such experiments when they have been tried with a very large number of people. CALCULATION OF THE FOOD VALUE OF FLESH. This ought to be based not only on the amount of nutriment contained in the flesh, but also on the amount capable of being absorbed and on the effect of the flavour. But inasmuch as the two last factors vary with each individual it is only possible to calculate the value approximately from the first, and to regard that food as the cheapest which contains the most nourish- ment. Konig adopts the method proposed by Emmerich, and starts from the fact that the actual market value of nitrogenous sub- stance (proteid) is higher than that of fat, and that carbohydrates are cheaper than fat. If 1 gramme of carbohydrate be taken to represent 1 nutrient unit in value, 1 gramme of fat, and of proteid represent 3 and 5 nutrient units respectively. Thus, for example, if 1 kilo, of beans cost 8d., Proteids, Fat, Carbohydrates, 230 grammes x 5 = 1150 nutrient units 20 „ x3= 60 „ 535 „ xl= 535 1745 Here the price of 1 food unit of beans would equal d. The following figures taken from Konig's table illustrate this method : — Water. Proteids. Pat. N.-Iree Extractives. Ash. Sum of nutrient units per liiio. Mutton, very fat, 47-91 14-80 36-39 05 0-85 1832-2 Sheep's tongue, , 67-41 14-29 17-81 0-09 1-00 1230-8 Sheep's liver, 69-30 21-64 4-98 2-73 1-35 1258-7 SYSTEMATIC EXAMINATION OF FKESH MEAT. 89 F. Strohmer* gives the subjoined table of the food value of different kinds of flesh calculated by this method : — Per Cent. Nutrient Units per kilo. Proteids. Fat. Carbo- hydrates. Beef, moderately fat, . 21-0 5-5 1215 „ lean, . 21-0 1-5 1095 Veal, . 20 4-0 1120 Pork, fat, . 14-5 37-5 1845 , , lean. 20-0 7-0 1210 Lard, 0-3 99-0 2985 Bacon, 5-0 78-0 2590 Game, 22-5 I'O 1155 Babbit, 21-5 10-0 1375 Heart, 18-0 8-0 1140 Kidney, 18-5 4-0 1045 Liver, 20-0 4-0 1120 Salt Herring, 19-0 17-0 1460 Liver Sausage, 11-0 14-5 21 1006 BlutwTirst (Blood ' Sausage), . J lO'O 9-0 20-0 790 According to Lehmann t this empirical method furnishes results which agree fairly well with the actual relation in price. SCHEME FOR THE EXAMINATION OF FRESH MEAT. The following outline for a preliminary examination of raw meat may be serviceable : — 1. The Colottk.^ — Normal. — White, as in lamb or veal; reddish, as in beef and mutton. Abnormal Melanosis, yellow, white, due to disease ; xantosis, dark purple (acute fever), reddish brown (COj poisoning), scarlet (CO poisoning or bacterial deposit). Iridescence, gray, violet, green (incipient decomposition) {cf. pages 70-72). 2. The Consistenot. — A skewer forced into the flesh should meet with equal resistance throughout. The opposite case may denote decom- position or the presence of abscesses. When cut with a knife the division should be even and regular [cf. pages 72 and 77). 3. The Odour. — See pages 73 and 78. 4. The Fat. — This should be present in suitable proportions. Extreme leanness denotes disease (^, pages 72 and 289). * Die Ernahrung des Menschen, p. 324. t Methods of Practical Hygiene, p. 413. 90 FLESH FOODS. 5. Reaction of the Meat Juiob towards Litmus. — Acid denotes sound meat or acid decomposition. Alkaline denotes decomposition or presence of alkaline salts as preservatives (cf. page 74). 6. Ebee's Test fok Puteefaotion. — This is carried out as described on page 75. 7. Degkbe of Moisture. — Abnormal moisture, as visible to the eye, is a symptom of several diseased conditions {cf. page 79). 8. Frozen Meat is detected by the appearance of the meat juice to the naked eye and under the •microscope (page 104). 9. 'Blown' Meat. — The general characteristics are described on page 77. 10. Meat treated with Antiseptics. — (a) Test for decomposition with litmus and Eber's test (pp. 74-75) ; (ft) Examine the meat fibres under microscope for decomposition and result of action of sulphites (pp. 117 and 121) ; (c) Test the meat juice for borates with turmeric paper (p. 119) ; (d) Test for salicylic acid (p. 122), and formaldehyde (p. 123). CHAPTEE V. METHODS OF EXAMINING ANIMAL FAT. Methods of Examiniag the Fat. — In the present writer's opinion the analytical methods described in the following pages will be found among the most suitable for the examination of the fat obtained by the methods described in the preceding chapter. For various modifications of these, and for alternative processes, the reader is referred to works dealing specially with fats and oils. Crystallization from Ether. — This may sometimes give an in- dication as to the nature of the fat. Pigs' fat, excepting that from the flare, is deposited in characteristic crystals with chisel- shaped ends, while beef- fat, mutton-fat, and horse-fat give fan-like bunches of needle-shaped crystals. Hehner and Mitchell * have shown that the form of the crystals depends on the proportion of stearic acid in the fat, and that on continued recrystallization of a lard which at first gives the broad-ended crystals, the deposits be- come more and more rich in stearic acid, and eventually assume the form of the crystals from beef-fat. Specific Gravity. — Accurate results are most readily obtained by the use of a Sprengel U-tube. Melting Point. — The method adopted by the Association of Bavarian Chemists consists in drawing the melted fat into a thin capillary tube, sealing one end, and leaving it for twenty-four hours. The tube is then tied to the stem of a thermometer, which is gently heated in a glycerin bath. The temperature at which the fat becomes perfectly clear and transparent is regarded as the melting point. Solidifying Point of the Fatty Acids. — The fatty acids are ■ melted in a test-tube and allowed to cool slowly until signs of incipient solidification appear, when they are stirred with a ther- mometer, graduated in fifths of a degree three times to the right and three times to the left. At a certain stage after this the mercury in the thermometer ceases to fall, and then suddenly * Analyst, 1896, p. 329. 92 FLESH FOODS. rises, often as much as half a degree, and remains stationary for a short time before commencing to fall again. This stationary point is taken as the solidifying point, and is also known as the Dalican ' titre.' By using the same apparatus and details of pro- cedure concordant results are readily obtained by this method. The Iodine Value. — This indicates the percentage of iodine or other halogen, calculated into its equivalent of iodine, absorbed by a fat. Hiibl Process. — The method which has hitherto been most widely employed is that of Hiibl, varied in the details of working by various chemists. The following is an outline of a method of procedure which, in essential particulars, is the same as that of Hiibl :— Two solutions are prepared : (1) containing 25 grammes of iodine in 500 c.c. of pure 95 per cent, alcohol (or rectified spirit), (2) containing 30 grammes of mercuric chloride in 500 c.c. of the same solvent. About 0-3 gramme of liquid fat, or 0'8 gramme of solid fat are dissolved in 10 c.c. of chloroform in a stoppered bottle. To the solution are added (1) 20 c.c. of the iodine solution, and (2) 20 c.c. of the mercuric chloride solution. Simultaneously a blanls deter- mination is made, the same quantity of chloroform and of the solution being placed in a stoppered bottle containing no fat. After three hours 10 c.c. of a 10 per cent, solution of potassium iodide is added to each bottle, and the liquid in each titrated with recently standardized sodium thiosulphate, starch paste being used as indicator. The difference between the blank determination and the other gives the amount of iodine absorbed by the quantity of fat taken. Care must be taken that there is always an excess of iodine during the absorption. From Wijs' experiments * it appears that the results are more accurate if the blank be titrated before the absorption rather than after it, and also that seven hours is a somewhat better time limit than three hours. Wijs' Method. — Recently Wijs' t has thrown light on the nature of the reactions which take place on mixing the Hiibl solutions and adding them to a fat, and has shown that the substance chiefly concerned in the absorption of the iodine is hypoiodous acid (HIO), formed by the action of the water present on the iodine chloride derived from the double decomposition between the iodine and the mercuric chloride. As this acid is extremely unstable, he has devised a means of obtaining it under such conditions as largely prevent its decom- * Analyst, abst., 1809, p. 95. t Zeit, angew. Chem., 1898, p. 291. DETERMINATION OF THE IODINE VALUE. 93 position. This is effected by preparing it by the action of water on iodine chloride (ICl + HgO = HCl + HIO), a solvent being chosen ■which contains only so much water as will decompose nearly the whole of the iodine chloride, and which at the same time will not be oxidized by the hypoiodous acid. A solution of iodine chloride in 95 per cent, acetic acid fulfils these conditions. This is prepared by dissolving 13 grammes of iodine in a litre of acetic acid, titrating the solution with standard thiosulphate, and passing a current of chlorine through, until the quantity of thiosulphate required is doubled. With a little practice this point can be readily found by the change in colour. The solution thus obtained is fairly stable, and is used in the same way as the mixed Hiibl solutions, with the exception that the length of time required for the absorption is very greatly reduced, the addition being complete in three or four minutes in the case of fats and oils with low iodine values, while not more than ten minutes are necessary with oils with high iodine values. The Bromine-Thermal Method. — This method, devised by Hehner and Mitchell,* affords a rapid means of determining the iodine value. It depends on the facts that on adding bromine to a fat or oil a considerable amount of heat is liberated, and that this heat is proportional to the degree of unsaturation. One gramme of the fat or oil is dissolved in 10 c.c. of chloroform or carbon tetrachloride in a test-tube packed with non-conducting material in a beaker, or preferably in a vacuum-jacketed tube.f A delicate thermometer (graduated in fifths or tenths of a degree) is inserted, and the temperature observed. One c.c. of bromine, previously brought to the same temperature as the chloroform solution, is then introduced, and a note made of the highest temperature reached. The difference between the initial and the final temperatures is the 'bromine-heat value.' By accurately determining the bromine-heat value and the iodine value of a number of edible fats and oils a ratio can be worked out between the two, so that subsequently it is only necessary to determine the bromine-heat value and to multiply it by the factor, in order to obtain the iodine value. Of course the same apparatus and method of working must alone be used or the factor will be a different one. The Saponification or Kottstorfer Value.^This indicates the amount of potassium hydroxide, in milligrammes, required to exactly convert the fatty acids in 1 gramme of a fat uito the potassium salts, with complete liberation of the glycerin. Hot Saponification.— From TS to 2 grammes of the fat are * Analyst. 1895, p. 146. t These may be obtained from F. Mttller, Holborn. 94 FLESH FOODS. mixed in a flask with an accurately measured excess of standard alcoholic potassium hydroxide, and heated on a boiling water-bath under a reflux condenser for about thirty minutes. The liquid is then titrated back with semi-normal acid, with phenol-phthalein as indicator. The alcoholic alkali is prepared by dissolving about 30 grammes of potassium hydroxide in a little boiling water, making up the solution to a litre with purified alcohol, and filtering it after standing for twenty-four hours. Cold Saponification* — From 3 to 4 grammes of the fat are dissolved in 25 c.c. of petroleum spirit and the solution mixed with 25 c.c. of standardized alcoholic potassium hydroxide (con- iJaining as little water as possible). The saponification is usually complete in a few hours, but it is advisable to allow the flask to stand overnight before titrating back the excess of alkali. Hehner Value. — This shows the percentage of insoluble fatty acids contained in a fat or oil. From 3 to 4 grammes of the fat are weighed into a small evaporating dish, where they are mixed with I to 2 grammes of potassium hydroxide and 50 c.c. of alcohol, and heated on the water-bath until completely saponified. The soap is evaporated to a pasty consistency and dissolved in about 150 c.c. of boiling water, the fatty acids liberated by adding hydrochloric or sulphuric acid, and the flask heated on the water-bath until they melt and form a clear layer on the surface. The contents of the flask are then poured on to a filter of thick paper, previously dried at 100° C., and weighed, and the insoluble fatty acids left on the filter are washed with boiling water until the filtrate ceases to redden litmus. The filter-funnel is then immersed in cold water, which generally causes the fatty acids to solidify. The water is drained off', and the filter and its contents dried at 100° C. in a beaker of known weight. The weighings, taken after two hours', and again after 4 hours' drying, usually agree within a milligramme. The Eeichert Value. — This indicates the definite proportion of volatile fatty acids obtained from 2 '5 grammes of a fat by Eeichert's distillation process. Two and a-half grammes of the purified and filtered fat are weighed into a small flask, fitted with a cork through which passes a short piece of glass-tubing, and saponified by adding 5 c.c. of pure alcohol and 6 c.c. of a concentrated aqueous solution of potas- sium hydroxide (free from carbonate) and heating on the water- bath for a short time. After expelling all traces of alcohol the dry soap is dissolved in 70 c.c. of boiling water, and the fatty acids * R. Henriques. Zeit. angew. Chem., 1895, p. 721 ; 1896, p. 221. Analyst, 1896, pp. 67 and 192. THE KEICHEET, ACETYL, AND ACID VALUES. 95 liberated by adding 5 c.c. of sulphuric acid of thef right strength to neutralize the alkali. A few pieces of pumice are introduced into the flask to prevent bumping, and the liquid gently distilled until exactly 50 c.c. of liquid have passed over. This distillate is filtered, the filter washed with boiling water, and the filtrate and washings titrated with decinormal solution of potassium or barium hydroxide. The number of c.c. required is the Eeichert value. In the Reichert-Meissl process 5 grammes of the fat are used, and the number obtained is considerably higher than the Reichert value. The Acetyl Value. — This indicates, among other things, the amount of hydroxylated fatty acids present in a fat. The method which gives the most reliable results is that of Lewkowitsch,* who defines the value as the number of milli- grammes of potassium hydroxide required to neutralize the acetic acid obtained by saponifying 1 gramme of the acetylated fat. The glycerides of any hydroxylated acids present are converted into their acetyl compounds by boiling the filtered and purified fat for two hours with an equal volume of acetic anhydride. The oily product is boiled with successive portions of water until the latter has no longer an acid reaction, and is then freed from water and filtered. From 2 to 4 grammes of the acetylated fat are saponified with a definite volume of standard alcoholic potassium hydroxide, the alcohol evaporated and the soap dissolved in boiling water. The amount of acetate present is then determined by either a distilla- tion or a filtration process. In the former an excess of sulphuric acid is added, from 500 to TOOc.c. of the liquid distilled by blowing a current of steam through the flask, and the distillate titrated with standard alkali. In the filtration process, a quantity of sulphuric acid exactly equivalent to the alcoholic potassium hydroxide used is added, the liquid warmed, the layer of fatty acids filtered ofi" and washed with boiling water, and the filtrate and washings titrated with standard alkali. Free alcohols will also be saponified, and, if present in any quan- tity, a correction must be made for them. A correction is also necessary when the fat contains any considerable proportion of volatile fatty acids (high Reichert value), t The Acid Value. — This indicates the amount of free fatty acids present in a fat. A weighed quantity of the fat is mixed with neutral alcohol, heated on the water-bath until the alcohol boils, and titrated with * Jow. Soc. Chem, Ind., 1897, xvi. pp. 503-506. t The. meaning of the acetyl value in fat-analyais is exhaustively discussed iu a recent paper by Lewkowitsch {^Analyst, 1899, p. 399). 96 FLESH FOODS. a standard solution of potassium hydroxide. The number of milligrammes of potassium hydroxide required to neutralize the free fatty aoids in 1 gramme of fat gives the acid value. DETEEMINATION OF INDIVIDUAL CONSTITUENTS. Separation of Liquid and Solid Fatty Acids. — Treatment of the Lead Soaps toith Ether. — Several methods * have been based on the fact that the lead salts of the unsaturated fatty acids are much more soluble in ether than those of the solid fatty acids (Varren- trapp). In each case there is only a fractional separation or con- centration, and the portion soluble in ether, although very much richer in liquid fatty acids, still contains solid fatty acids, while the insoluble portion is not free from liquid fatty acids. As, how- ever, it is possible, by working under exactly the same conditions, to obtain concordant results, the method in one or other of its modifications is widely employed, and often affords valuable information. The following process is essentially that of Rose : — One gramme of the mixed fatty acids is placed in a stoppered flask with 05 gramme of lead oxide, and about 80 c.c. of ether, and after standing for twenty-four hours, with an occasional shake, the liquid is made up to 100 c.c. with ether, the flask well shaken, and the insoluble matter allowed to settle. Twenty-five c.c. of the ether are then withdrawn by means of a pipette, the end of which is covered with a porous plug of cotton-wool, to serve as a filter. The solvent is evaporated and the residue dried in a current of carbon dioxide, and weighed. The lead it contains is then determined by adding 2 '5 c.c. of dilute sulphuric acid (1 : 5), digesting on the water-bath, adding 40 c.c. of 95 per cent, alcohol, collecting the lead sulphate on counterpoised filters, washing it with alcohol, drying and weighing. From the percentage of lead in the dried sulphate the proportion of fatty acids which were in combination with it in the residue may be calculated, and also their molecular weight. Determination of the Iodine Value of the ' Liquid ' Fatty Acids. — Fifty c.c. of the ethereal solution are withdrawn from the flask with the filter pipette and shaken with dilute hydrochloric acid in a separating funnel, in order to liberate the fatty acids ; the ethereal layer is washed with successive portions of water until free from chloride, after which 25 c.c. are withdrawn and evapor- ated to dryness in a weighed flask, and the iodine value of the residue determined in the usual manner. From the time of the liberation of the fatty acids the greatest care is necessary, to t Oudemans, /. prale. Chem., 99, p. 407 ; Muter and De Koningh, Analyst, 1889, p. 61 : Kremel, Pharm. Centralb., 5, p. 337 ; Rose, J. Hoc. Chem. Ind., 18S7, p. 306. METHODS OF SEPARATING FATTY ACIDS. 97 prevent their oxidation, and throughout the washing and evapora- tion the air in the separating funnel and the tiask must be replaced by carbon dioxide. (ii.) Treatment of the Lead Soap with Benzene. — Finding that the lead salts of the unsaturated fatty acids were much less soluble in benzene than in ether, Farnsteiner * has devised the following method of separation, in which his experiments with known mix- tures show that the proportion of liquid fatty acids obtained are from 1 to 3 per cent, too low, while that of the solid acids is in the maximum 1'65 per cent, too high : — From 0'6 to 1 gramme of the fat is saponified in an Erlenmeyer flask with alcoholic potassium hydroxide, the solution neutralized with acetic acid, and, after evaporation of the alcohol, the soap dissolved in 100 c.c. of boiling water and precipitated with 30 c.c. of a boiling solution of lead acetate (containing about 1 gramme). When cold the liquid is filtered and the residue in the flask washed with cold water, freed from the latter as completely as possible, and dissolved in 50 c.c. of hot benzene. The solu- tion is left at the ordinary temperature for fifteen minutes, and is then cooled for about two hours at 8° to 12° C. In order to separate the liquid from the crystalline deposit, the flask is closed with a cork, having two holes, through one of which passes a short straight tube, while the other holds a tube reaching to the bottom of the flask and having its exterior end bent downwards outside the flask. The interior opening of the tube is covered with a plug of cotton wool which serves as a filter, and the liquid is driven upwards through this by forcing air into the flask through the short straight tube. When the liquid has been removed as completely as possible in this way, the flask is washed with 10 c.c. of benzene at 10° C, which is similarly expelled. The precipitate is then dissolved in 25 c.c. of hot benzene, again cooled for an hour at 8° to 10° C, and the liquid again filtered. In the same way a third precipitation and filtration are carried out, so that alto- gether from 120 to 130 c.c. of the benzene filtrate are obtained. The liquid fatty acids are recovered from the united filtrates by shaking the latter with 10 c.c. of hydrochloric acid, filtering the solution of fatty acids through cotton wool, into a flask, and distil- ling off the benzene in a current of hydrogen, to prevent oxidation. The solid fatty acids are determined by heating the insoluble lead salts in a flask with 25 to 30 c.c. of benzene for a short time, then adding dilute hydrochloric acid (1:10), continuing the heating for about fifteen minutes under a reflux condenser, washing the solu- tion, and evaporating the benzene. When free fatty acids are to be examined the best method is to * Zeit. Nahr. u. Genussm., 1898, 1, pp. 390-399. G 93 FLESH FOODS. dissolve them in benzene and to heat the solution under a reflux condenser with lead hydroxide, obtained by precipitating a solution of lead acetate with sodium hydroxide, washing the precipitate with water, alcohol, and ether, drying it at a gentle heat, and finely pow- dering it. The proportions required for one part by weight of solid and liquid fatty acids are 0'4 and 0'2 parts respectively. Determination of the Iodine Value 0/ the Liquid Fatty Acids. — This may be done with the residue of acids obtained in the manner described above, every precaution having been taken to prevent their becoming oxidized. The risk of oxidation is greatly reduced and the manipulation simplified by determining the iodine value of the fatty acids while still in solution in the benzene. Farnsteiner * has found that benzene from which all thiophene has been removed does not absorb a trace of iodine on treatment with HUbl's solution, and on this fact bases the following method : — From 1 to 2 grammes of the fat are converted into the lead salts of the fatty acids in the usual manner, and dissolved in 100 c.c. of benzene (free from thiophene) at a gentle heat. After being left for ten to fifteen minutes, until a precipitate commences to form, the flask is allowed to stand for two hours at a tempera- ture of from 8° to 12° C, and the liquid then filtered without subsequent washing of the precipitate. After shaking the filtrate with about 100 c.c. of dilute hydrochloric acid (1:10), until the fatty acids are liberated, the benzene solution is washed twice with water and filtered. Two portions of 25 c.c. are taken from the filtrate and treated with the Hiibl solution in the usual manner, whilst a similar third portion is evaporated in a current of hydrogen, and the residue weighed in order to determine the quantity present in the other fractions. Benzene t can be freed from thiophene by heating 120 c.c. to the boiling point under a reflux condenser with 5 '8 grammes of aluminium chloride, and distilling, care being taken to exclude moisture. The distillate is washed with sodium hydroxide solution and dried with calcium chloride. Treatment of the Zinc Salts loith Ether. — In Jean's method the fat is saponified with alcoholic potassium hydroxide, the excess of alkali neutralized with acetic acid, and the alcohol evaporated on the water-bath. The soap is dissolved in hot water, a hot solu- tion of zinc acetate (1 part to 2 parts of fat) added, and the zinc soap washed with hot water and alcohol, pressed between filter- paper, and extracted with about ten times its volume of anhydrous ether for fifteen to thirty minutes, under a reflux condenser. After cooling, the solution is filtered into a separating funnel, * Zeit. Untersuch. Nalir. Gemiesm., 1898, p. 529, t Heusler, Zeit. angew. Chem., 1896, p. 750. ESTIMATION OF STEARIC ACID. 99 shaken with dilute hydrochloric acid, and the ethereal layer con- taining the liberated fatty acids, washed with water, and parts of it filtered into weighed flasks, where the ether is evaporated and the iodine value of the residues determined in the usual way. During the filtrations and evaporations every precaution is taken to prevent oxidation. Bbmer* has recently made experiments on the determination of the iodine value of the zinc salts without previous conversion into fatty acids. He points out that since the molecular equivalents of the higher unsaturated fatty acids differ but slightly, a variation in the percentage of those acids in a mixture would not have a very great influence on the result. Thus 100 parts of oleic acid correspond to 111'19 of zinc oleate; 100 of linolic acid to 111-27 of zinc linoleate; and 100 of linolenic acid to 111-35 of zinc linolenate. Hence, without risk of a considerable error, the mole- cular equivalent of the zinc salts of mixed liquid fatty acids may be taken as that of the oleic acid salt (627-1) ; and since 100 parts of zinc oleate correspond to 89'94 parts of oleic acid, the iodine value of the liquid fatty acids (taken as oleic acid) may be calcu- lated by dividing that of the zinc soap by 0-8994 or multiplying it by 1-112. (iii.) Treatment of the Fatty Acids with Sulphuric Acid and Extraction of the Saturated Acids with Petroleum Spirit.^ — From 0-5 to 1 gramme of the fatty acids are melted in an Erlenmeyer flask, the flask chilled in ice water, 3 c.c. of 85 per cent, sulphuric acid added, and the temperature allowed to rise. When once the reaction commences a clear solution is rapidly obtained, and the flask is again cooled. Fifty c.c. of petroleum spirit are then introduced, the flask well shaken, the petroleum spirit decanted into a separating funnel, the flask rinsed out twice with 10 c.c. of petroleum spirit, the total extract washed with water, the solvent evaporated, and the residue, consisting of the saturated fatty acids, dried and weighed. % Determination of Stearic Acid. — Hehner and Mitchell § have devised a method of estimating this constituent, in which the fatty acids are crystallised from alcohol previously saturated with pure, or nearly pure, stearic acid, at a definite temperature. The stearic acid is most readily obtained by recrystallising the fatty acids of cocoa butter from alcohol until a product is obtained which melts between 68° and 69° C. An excess of this is dissolved in 95 per cent, alcohol, and the flask kept immersed for twelve * Zeit. f. Untersuch. Nahr. Genussm., 1898, p. 541. + E. Twitchell, Journ. Soc. Ohem. Ind., 1897, p. 1002. t According to Lewkowitsoh {Analyst, 1900, p. 6i) this method does not j'ield quantitative results. § Analyst, 1896, p. 316. 100 FLESH FOODS. hours in ice-water. In the morning the liquid is drawn off by means of a suction filter, without withdrawing the flask from the ice-chest. The filter consists of a thistle funnel covered with a linen cloth, and the method of manipulation is shown in the accompanying figure. From 0-5 to 1 gramme of the fatty acids of the fat under examination are dissolved in 100 c.c. of this saturated alcohol, and the flask left immersed in the ice-water in the ice- chest for twelve hours. The liquid is then drawn off through the filter-tube, the flask washed out three times with 10 c.c. of the saturated alcohol at 0° C, each por- tion being withdrawn in the same manner, and the resi- due dried at 100° C, and weighed. An allowance, ex- perimentally determined to be 5 milligrammes, is made for the amount of stearic acid contained in the satu- rated alcohol unavoidably left in the flask. {Cf. pp. 54 and 56.) Detennination of Oleic Acid. ■ — Fariisteiner * has based a method of de- termining this acid on the insolubility of barium oleate in a mixture of cold benzene and alcohol. The fat is saponified and barium chloride added to the hot soap solution. The precipitate is washed with water and dissolved in 50 c.c. of hot benzene containing 2'5 c.c. of 95 per cent, alcohol. The precipitate, which deposits on cooling, is redissolved in 50 c.c. of benzene containing 10 c.c. of alcohol, and the resulting precipitate again recrystallised from a mixture of 50 c.c. of benzene and 20 c.c. of alcohol. t The fatty acids recovered from the insoluble salts consist of saturated fatty acids and oleic acid, which can be separated from one another by Farnsteiner's method (p. 97). * Zeit. Untersuch. Nahr. Oenussm,., 1899, pp. 1-27. f Lewkowitsch has recently shown {Analyst, 1900, p. 64) that this method is unreliable. It might be possible, however, to obtain satisfactory results by previously saturating the solvent with pure barium oleate. Fig. 17. ESTIMATION OF LINOLIO AND LINOLENIC ACIDS. 101 The barium salts of the fatty acids can also be prepared directly from the fats by saponifying them with a solution of barium hydroxide in equal volumes of benzene and methyl alcohol. Determinatioii of LinoUc Acid. — According to Farnsteiner it is possible to estimate this acid by taking advantage of the insolubility of its bromide in cold petroleum spirit. The fatty acids of the oil or fat are dissolved in chloroform or petroleum spirit, the solvent and excess of bromine evaporated, and the deposit filtered off, washed, dissolved in petroleum spirit, recrystallised, collected, and weighed. As a rule it was necessary, where only small quantities of linolic acid were present, to brominate the liquid fatty acids (p. 97), or the soluble fatty acids obtained in the separation of oleic acid as a barium salt (p. 100). In this way lard was found to contain traces of both linolic acid and linolenic acid. Horse fat contained 9'9 per cent, of linolic acid, which was also found in ox-tallow, accompanied by traces of linolenic acid. Detenninatioii of Linolenic Acid. — Indirect Estimation. — Hehner and Mitchell* have devised the following method: — On adding bromine to a chilled acetic acid solution of the total liquid fatty acids of an oil, there is an immediate precipitate if linolenic acid be present in more than traces, but this may also contain linolic bromide if it be present in any quantity. The precipitate is collected on a filter, washed first with cold acetic acid so as to remove oleic dibromide, and then with very cold ether, dried, and weighed. The bromine it contains is deter- mined, and the relative proportion of linolenic hexabromide calculated by means of the formula 63-3a; (100-«)53-3 _ 100 "•" 100 "'^ or a; = 10(m-53-3), in which m equal the percentage of bromine found, x the required percentage of hexabromide, and 63-3 and 53-3 the respective percentages of bromine in the pure hexa- and tetra-bromides. Direct Estimation. — In Farnsteiner's method of estimating linolic acid (vide supra) it was found that in some cases the bromides of the liquid fatty acids were not completely soluble in hot petroleum spirit, and that the insoluble residue had the characteristics of linolenic hexabromide. Hence it seems probable that this may be made the basis of a method of separating linolic and linolenic acids. * Analyst, 1898, p. 314. CHAPTER VI. THE PRESERVATION OF FLESH, AND THE COMPOSI- TION AND EXAMINATION OF PRESERVED FLESH PRODUCTS. The Decomposition of Flesh. The organic substances vcliioh compose the cells of the animal tissues and fluids are, as it were, in a state of unstable equilibrium, a constant series of molecular changes going on, "with destruction and reconstruction of the cell materials. So long as the cell is endowed with the force known as 'life,' it is able to resist the dis- integrating effect of the numerous micro-organisms which, under suitable conditions, speedilj break down complex animal com- pounds into simpler and more stable bodies. But when once the cell is dead, the process of decay or putrefaction speedily com- mences, unless means be taken to destroy or render inert the bacteria already present, and to prevent the access of others. The conditions essential for the bacterial decomposition of iiesh are the presence of a sufficient quantity of moisture, and a suit- able temperature, while the presence of atmospheric oxygen is often an accelerating influence. The methods adopted in the preservation of meat are based on a consideration of these facts, and for convenience may be con- sidered under the following heads: — 1. Preservation by Cold ; 2. Drying; 3. Salting; 4. Smoking; 5. Heat-Sterilisation and Exclu- sion of Air; 6. Antiseptic Agents. Obviously this classification is by no means an exact one, as the divisions overlap one another in many cases. Preservation by Cold. This method of preservation is perhaps more extensively employed than any other, especially in Russia, where the climate is favour- able for its natural application. Preservation by means of arti- PEESEKTATION OF FLESH FOODS ; COLD. 103 ficial cold is also in general use, and enormous quantities of frozen meat are daily supplied to the markets of London and other large cities. The numerous methods of cold preservation which have been described are based upon either (1) freezing the flesh and keeping it frozen ; or (2) keeping it at a temperature of only a few degrees below zero (C). Alterations in Frozen Flesh. — Owing to the slow, continuous action of the sarcolactic acid, meat which has been frozen is often exceptionally tender. On the other hand, owing to the loosening of the intermuscular tissue, bacteria can more readily penetrate into the interior of the thawed flesh, and bring about more rapid decomposition. Considerable care is required in the thawing, since if this be done too suddenly the meat when cooked is often wanting in flavour. Action of Cold on Bacteria. — Bacteria in general, and especi- ally those which bring about putrefaction, appear to be endowed with extraordinary powers of resistance to the action of cold. Pictet and Young * exposed cultivations of anthrax bacilli, of B. subtilis, and of other bacteria, in wooden boxes, to a tempera- ture of - 70° to - 76° C. for twenty hours, and finally for a long period at - 76° to - 130° C, but did not succeed in destroying their vitality. Colemann and Mickendrick* obtained similar results. In their experiments flesh was kept for at least six hours in hermetically-sealed boxes at temperatures from - 6° to - 130° C, but in every instance the flesh, after being kept at a slightly warm temperature, began to decompose in from ten to twelve hours, though protected from subsequent infection. But cold, although it does not destroy micro-organisms, pre- vents their development, or at least does so in the case of the putrefactive bacteria, which at low temperatures are imable to decompose the proteids of flesh. There are, however, certain non- proteolytic bacteria which are capable of developing in frozen meat, and especially in that which is kept at a temperature of 0° C, instead of several degrees lower. To this cause. Lafar t attributes the unpleasant flavour sometimes acquired by meat which has been kept in an ice-chamber for several days. This is confirmed by Popp,t who states that in cement- lined storage chambers the walls, when moist, swarm with bacteria, which, when grown on beef-gelatin, produce a mouldy flavour, and he considers them to be the cause of the objectionable flavour frequently developed in stored meat. * Ostertag, ffandbuch der Fleischieschau, p. 535. + Technical Mycology, p. 213. iZeit. FUischu. Milch Eyg., 1898, p 33. 104 FLESH FOODS. The Detection of Frozen Meat. — When fresh blood is exposed to a temperature of from 10° to 15° below zero (C), it solidifies, and, when examined under the microscope, shows ruptured cor- puscles. This was first described by G. Pouchet in 1866, and has been applied by Maljean * to the recognition of frozen meat. A drop of the blood or meat-juice is expressed from the meat on to a glass slide, covered with a thin glass, and placed under the micro- scope as rapidly as possible in order to avoid solidification. The juice from fresh meat shows numerous red corpuscles of normal colour and shape floating in a colourless serum, whereas the cor- puscles in the drop taken from the frozen meat are all more or less distorted in form, and completely decolorised, whilst the sur- rounding liquid has a relatively dark colour. A difl'erence is also apparent to the naked eye, the juice from fresh meat being more abundant and of a redder tint than that from frozen meat. On placing a fragment of the frozen meat in a test-tube containiug some water, the liquid becomes coloured much more rapidly and intensely than when fresh meat is used. Preservation by Drying. During the process of drying in the sun or by artificial heat flesh loses a large proportion of its water, so that in the finished product one of the essential conditions for the development of bacteria is absent. As a rule such preparations keep well if pro- tected from moisture, but during the drying they lose much of the flavour of the fresh meat. The best-known examples of this method of preservation are the American preparations, pemmican, and charque, and flesh powder. Pemmican. — This was formerly prepared by the North Ameri- can Indians from buffalo flesh, but now usually consists of beef. The flesh is cut into strips, dried in the sun, minced as finely as possible, mixed with equal quantities of fat, and worked up into a paste. According to Dr. Chaumont the finished product contains about 35 per cent, of nitrogenous substance and 56 per cent, of fat. Charque. — Enormous quantities of this form of dried flesh are prepared in various parts of South America. The meat, after removal of the fat as completely as possible, is cut into thin strips, which are covered with flour, dried in the sun, and rolled and pressed into a compact mass. In Brazil it is mixed with sugar before drying {charque dulce), or salted and dried {came secca), or salted and pressed between stones before drying {came Tassajo). * Journ. Pharm. Chim., 1892, 25, p. 348. PRESERVATION OF FLESH FOODS: DRYING. 105 According to Chevalier * it should have a dark red colour, the muscular fibre should be hard, and no liquid should exude on applying strong pressure with the fingers. Beef loses about a quarter of its weight in the process. Hofmann t gives the following figures as representative of the composition of fat and lean charque : — Per Cent. Dry Substance. Water. Nitro- genous Sub- stances. Tat. Salts. Sodium Chloride. Nitro- genous Sub- stances. Fat. Nitrogen. Fat Charque, . Lean Charque, 40-2 36-1 48-4 46-0 2-1 3-7 8-3 15-2 6-3 14-1 80-93 71-98 5-17 4-22 12-95 11-91 In 1855 Giradin % made the following comparative analyses of the composition of French beef and South American charque : — French Beef. Charque. Fresh. Dried at 100° C. As Imported. Dried at 100° C. Water, . Fibrin, . Fat, Albumin, Extractives, . Soluble Salts, 75-9 15-70 1-01 2-25 2-06 2-95 6.V4 4-19 9-34 8-55 12-24 4911 24-82 0-18 0-70 3-28 21-07 48-78 0-35 1-38 6-44 41-39 Phosphoric Acid, . Nitrogen, Sodium Chloride, . 0-222 3-000 0-489 0-925 12-578 2-030 0-618 4-620 11-516 1-216 9-101 22-630 But although charque is richer in phosphates and nitrogenous substances than fresh beef, it can only be eaten in small quantities on account of the large amount of salt which it contains, and this also renders it extremely hygroscopic. Moreover, any fat which * Diction, des Alterations et Falsifications, p. 561. t Bedeutwng der Fleischnahrung, p. 162. t Diction, des Alterations et Falsifications, p. 562. 106 FLESH FOODS. is left in it is very liable to become rancid. Hence, in spite of its cheapness (25 to 35 centimes per kilo, in La Plata), it has never come into general use in Europe. Flesh Powder. — Various preparations of powdered flesh or flesh powder have been introduced into commerce, but, as a rsule, the difficulty has been to prevent them acquiring an unpleasant flavour from alterations in the fat which they contain. Kbnig has confirmed Kubner's statement, that such dried flesh is as digestible as fresh meat. The lean flesh is dried first on the surface in a special apparatus at a low temperature, which is subsequently raised. When dry the flesh is pulverised and salted. The following analyses of a German patent flesh powder (' came pura'), which is no longer in the market, have been made by Konig * and Strohmerf : — Water. Nitro- genous Sub- stances. rat. N.-free Extrac- tives. Salts. Potas- sium. Phosphoric Acid. Klinig, Strohmer, . 10-99 10-81 69-50 70-24 5-84 5-61 0-42 13-25 13-34 1-85 1-62 Strohmer also found that 97-56 per cent, of the nitrogenous substance was of a proteid nature, and that 99-2 per cent, of this was digestible. The ash contained 8-77 per cent, of sodium chloride. Various substances, such as biscuits, meat cocoa, chocolate, etc., have been prepared from such flesh powder. Strohmer gives the following results of the analyses of some of these preparations con- taining ' came pura ' : — Water. Nitrogenous Substance. Fat. Carbo- hydrates. Ash. Digestible Nitrogenous Substances. Meat biscuit, ,, cocoa, ,, chocolate, . 5-98 6-25 2-10 12-56 22-63 10-76 12-37 30-13 25-83 67-09 34-65 59-10 2-00 6-34 2-22 92-5 65-7 72-7 * Loc. dt., ii. t Die Ernahruitg des Menschen, p. 130. PRESERVATION OF FLESH FOODS : SALTING. 107 The writer is indebted to Mr. Otto Hehner for the following analyses of English meat biscuits which are still manufactured : — • Water. Fat. Albumin. Cellulose. Ash. by'd[fferen'c°e'. English meat biscuit. 7-53 16-77 16-05 0-97 1-68 57-00 Dried Fish. — In many places small cod, haddock, and stockfish are preserved by slitting them down the middle and drying them in the air. Dried stockfish (Kabeljau) is very extensively used. According to Strohmer* it contains : — Water, 16-16 ; nitrogenous matter, 78-91; fat, 0-78; and salts, 1-52. It is as digestible as flesh powder, and costs less. Blood Meal. — In Sweden purified, dried blood, in the form of a powder, is a common article of food.* Preservation by Salting, This is one of the oldest and most widely iised processes of preserving meat. The salt acts partially as a dehydrating agent, combining with the water in the flesh, and partly as an antiseptic, though its value in the latter respect has frequently been over- rated. Methods of Salting. — In one method the flesh is well rubbed with salt, then pressed, the salting repeated, the meat being finally placed in barrels and covered with the salt liquid obtained from the pressings. Another method consists in placing the meat in casks in layers, with salt between each layer. The salt withdraws water from the flesh, and the brine formed penetrates the fibres. In Eckart's Munich quick-salting process, the meat is impreg- nated, under pressure, with a 25 per cent, solution of sodium chloride for twenty-four hours, and then smoked. It is claimed that the loss consists, in the main, of only water and a little phos- phoric acid, that the meat has a better flavour, and that any trichinae are completely destroyed. Cirio's process, first exhibited in Paris in, 1867, is very similar in character, the meat being kept in vacuo and brine forced in. Addition of Mtre. — As one of the results of salting meat is, that decolorisation takes place, it is customary to add a small proportion of potassium nitrate to counteract this. According to Lehmann a very little suffices, but it must not be lost sight of that nitre is a poisonous substance. Five grammes of the salt may cause severe illness, and 8 grammes have been known to * Loc. cit., p. 132. 108 FLESH FOODS. cause death. The effect on the human system of the continued use of meat containing nitre has not yet been determined. Influence of Salting on Bacteria. — From the experiments of Forster * it appears that the streptococci of erysipelas, the bacilli of swine erysipelas, and Streptococci pyogenes can live for weeks, and even months, in salted flesh. The bacilli of tuberculosis retain their virulence for over two months, and while the bacteria of anthrax perish in from eighteen to twenty-four hours, their spores retain their vitality for a very long period. Influence of Salting on the Flesh. — Volt's analysis* tends to show that the nutritive valne of flesh is only slightly diminished after fourteen days' salting. He found the percentage loss to be — Water, 10-4; organic matter, 2-1; albumin, I'l ; extrac- tives, 13-5; phosphoric acid, 8-5. The amount of salt taken up by 1000 grammes of the fresh flesh was 43-0 grammes. E. Polenske,t however, found that beef^ after being pickled for three weeks, had lost 7-77 per cent, of its nitrogenous con- stituents, and 34-72 per cent, of its phosphoric acid. After three months the loss in nitrogen was lO'OS per cent., and the loss of phosphoric acid (PjOj) 54-46 per cent., while after six months these figures had risen to 13-78 and 54-60 per cent, respectively. From this Polenske concluded that the meat was completely altered in character as a nutrient substance. Moreover, on account of the large amount of salt, it cannot be used as a substitute for fresh meat for a continued period without injurious effects. Strohmer \ gives the following comparative analyses of the com- position of fresh and salted herring, and of salted anchovies : — Water. Nitrogenous Suhstanoes. Fat. Ash. Sodium Chloride. Fresh Herring, Salt Herring, Salt Anchovies, 80-71 46-2 57-8 10-11 18-9 22-3 7-11 16-9 2-2 2-07 16-4 23-7 iT-o 20-0 The Composition of the PicklLng riuid. — In Polenske' s experi- ments this liquid contained nitre and salt, and as the pickling proceeded, the nitrate became reduced to nitrite and ammonia. Gerlach § gives the following analysis of an old herring pickling * Ostertag, loa. cit., p. 526. + Loc. cit., p. 133. t Jahresher. Nahr. u. Genussm,., 1891, p. 40, § Sandbuch der Fleischkunde, p. 898. PEESEKVATION OF FLESH FOODS: SALTING. 109 fluid: — Water, 74-40; sodium chloride, 2278; ammonium lac- tate, 0'68 ; soluble proteid substances, 0'820 ; other organic matter, potassium sulphate, and calcium phosphate, 1'352 per cent. Hoffmann* and Werthe also found volatile bases, such as trimethylamine and propylamine. The pickling liquid, from whatever flesh originating, is often very poisonous to animals. Caviar. — This is the salted roe of the sturgeon and of other fish. It is prepared by washing the roe with salt water, leaving it in brine for some time, pressing it to remove foreign substances, again treating it with salt water, pressing it through a hair sieve, and finally packing it in salt. In the fresh state caviar is of a greenish shade, which gradually darkens on keeping. The most prized is the Astrachan caviar, which is prepared at the mouth of the Volga. The German Elbe caviar contains smaller granules, and is prepared from different kinds of fish. It has a sharper taste than the Eussian caviar. There is also an American variety, which has small granules, and contains more or less gelatinous matter. One of the best kinds in commerce is the Saxony caviar, which is packed in linen, and is less salt than the others. The poorer varieties are pressed and salted, and sold as ' pressed caviar ' or ' fish-cheese.' Composition. — From the analyses of Gobley t and of Konig,J caviar has the following proximate composition : — ■ Water. Nitro- genous Sub- stances. Fat. N.-free Sub- stances, etc. Ash. Dry Substance. N.-sub- stances. Fat. Nitro- gen. Caviar, . . )j • . Pressed caviar, 48-13 43-89 30-89 26-58 30-79 40-33 14-57 15-66 18-90 4-16 1-67 6-56 8-09 9-88 54-89 58-36 24-02 27-35 8-78 9-36 Examination of Caviar. — W. Niebel § gives the following as the characteristics of good caviar: — 1. The colour should be grey or black; 2. The size of the eggs varies from 2 to 3-5 mm.; 3. There should be no smell, although an acid smell is frequently * Handbuch der FleiscliTcwnde, p. 898. t Strohmer, Die Ernahrung des Menschen, p. 143. X Nahrimg Genussmitt., ii. p. 128. § Heit. Fleisch u. Milch Hyg., 1893, i. p. 5. 110 FLESH FOODS. to be observed in commercial varieties ; 4. Foreign substances must be absent, sucli as hair or sand, due to careless preparation, or oil and sago, fraudulently added. The best caviar is neutral to litmus paper, but the poorer kinds are usually acid. The latter also frequently contain traces of free ammonia, hydrogen sulphide, and free fatty acids. Preservation by Smoking. The process of smoking preserves flesh partly on account of the drying action of the heat and partly through the antiseptic action of some of the substances in the smoke, such as creosote, formal- dehyde, and pyroligneous acid. According to Marasse, the creosote in wood smoke consists of a mixture of C^HgO^, CgHj^Oj and CgHjgOj. It coagulates the albumin of the meat, forming a pro- tecting envelope. The best wood for the production of the smoke is beech, while pine and fir are quite unsuitable, on account of the resins they contain. There is no loss of nutriment, such as occurs in salting, and Strohmer * found that smoked meat was as digestible as fresh meat. Methods of Smoking. — There are two chief processes of smok- ing : — 1. The flesh is slowly smoked for twenty-four hours at 25° C, or in the case of sausages and fish at 70° C, and then for a short time at 100° C. ; or 2. The flesh is placed directly in the hot smoke. Beu t examined a large number of different commercial smoked meat products, and found that those prepared by the slow process contained many more naicro-organisms. Intermittent smoking is bad, since it favours decomposition. Action of Smoke on Bacteria. — Serafini and Ungarot proved that smoke acts very energetically on pure cultivations of bacteria. The bacilli of anthrax and staphylococci perished in two and a half hours at the outside, hay bacilli in three and a half hours, and the spores of the anthrax bacilli after eighteen hours. On treating flesh infected with anthrax in the same manner, it was found, however, that the bacilli in the interior of the flesh did not perish, since the smoke could only penetrate very slowly on account of the coagulation of the albumin. Hence the conclusion arrived at was that smoking checks the development of bacteria, but does not destroy them. Forster | met with the same experience in the case of the bacilli * Die Ernahrung des Menschen, p. 135. + Ostertag, Bandb. der FUischbcschau, p. 528. + Ostertag, loc.cit., p. 384. PKESEKVATION OF FLESH FOODS: SMOKING. Ill of tuberculosis, which he found were still virulent, after the flesh which contained them had been both salted and smoked. Composition of Smoked Flesh.— Strohmer* gives the subjoined analyses of various kinds of smoked flesh : — Water. Nitrogenous Substances. 'Fat. Ash. Ham, ordinary, .... ,, Westphalian, . Smoked Beef, ,, Ox Tongue, . „ Herring, 59-73 27-98 47-68 35-74 64-49 25-08 23-97 27-10 24-31 21-12 8-11 36-48 15-35 31-61 8-51 7-08 10-07 10-59 8-51 1-24 The following analyses of smoked and salted meat and fish are taken from Konig t : — Water. Nitro- genous Sub- stances Fat. Ash. On Dry Substance. Sodium Chloride. Nitro- genous Sub- stances Fat. Nitro- gen. Smoked Horseflesh, . Westphalian Ham, . American Bacon, Smoked Goose Breast, 49-15 28-11 9-15 10-70 41-35 31-84 24-74 9-72 2-62 21-45 6-49 36-45 75-75 77-80 31-49 12-53 10-54 5-38 6-60 4-56 62-61 34-41 10-70 2-91 36-57 12-76 50-69 83-38 87-12 53-69 1002 5-50 1-71 0-47 5-85 Mackerel (mean of 4), Herring ( „ 3), Salmon ( „ 2), 44-45 46-23 51-46 19-17 18-90 24-19 2-2-43 16-89 11-86 13-82 16-41 12-04 11-42 14-47 10-87 34-64 35-27 49-88 40-10 31-20 24-44 5-54 5-64 7-98 Iiifl.uence of Smoking on the Flesh. — During the process of pickling and smoking the colouring matter of flesh undergoes alterations, as may be observed with the spectroscope. Utescher J found that smoked ham and Hamburg smoked flesh had invariably an alkaline reaction. The Composition of American and Dutch Bacon. — Kaiser was unable to find any difierence in the composition of these kinds of Die Emahrung des Menschen. Apoth. Ztg., 1894, p. 765. t Loc. cit., i. pp. 206 and 228. 112 FLESH FOODS. bacon. Lutz,* however, from the results of his comparative analyses, came to the conclusion that there was a considerable difference, and gave the following figures as representative of their composition : — Water. Nitrogenous Matters. Fat. Ash. American Bacon, Dutch Bacon, .... 9-0 12-0 9-0 14-5 71-5 63-5 10-5 10-0 Preservation by Heat-SterDisation and Exclusion of Air. A very large number of processes may be grouped under this head, but all are based to a greater or less extent on that devised by Appert in 1809, in which the provisions were heated in earthen- ware vessels and protected from subsequent infection by hermetic sealing. In some of the later patents the air in the vessel is replaced by an inert gas such as nitrogen or carbon dioxide, but such methods as these seem unlikely to replace the simpler ones in use. Canned Meats. — Modifications of Appert's process have been used for the preservation of almost every description of food, but especially for fruit, meat, and fish. Cans are employed to a much greater extent than glass or earthenware, owing to their greater strength, and the readiness with which they can be made air- tight. In the large American factories, steam retorts are used for the sterilising, but, in the smaller factories, the cans are immersed in boiling water or in a salt bath. A small hole is left in the cover, and, after the sterilisation, and while the can is still filled with steam, this is closed with a fragment of solder. Finally, the cans are left for a week, and are then tested by striking each on the head with a wooden hammer. If the cap sinks down slowly, the process has been properly carried out, but if it is elastic and springs back, it is what is termed a 'swell-head,' and is rejected. Preparation of Corned Beef. — In the preparation of this, finely- divided flesh, freed from sinews and fat, is pickled in vats, and, when salted, is cooked and packed by means of steam pressure into cans, which are immediately sealed. After standing for * Jahresber. Nahr. Genussm., 1891, p. 40. HEAT-STEKILISATION — CANNED MEATS. 113 three to six hours in boiling water, the cans are pierced to allow water and fat to escape, again soldered up, and again placed in boiling water for several hours. Composition of Canned Meats. — Kdnig gives the following table of the percentage composition of some well-known canned meats : — On the Dry Substance. Nitro- Water. genous Sub- stances Fat. Ash. Nitro- genous Sub- stances Fat. Nitro- gen. (■ 21-07 ) American meat, salted, 49-11 28-87 0-18 \ (NaCl \ 1. 11-52) ) 56-73 0-35 9-08 Prepared by Wilson, . 57-3 28-9 10-2 3-6 67-68 23-75 10-83 „ Canning &Co., . 49-2 25-7 21-6 3-5 50-59 42-52 8-09 ,, Brougham, 48-9 27-7 19-0 4-4 54-21 37-18 8-67 Australian, 54-03 29-31 12-11 4-55 63-76 26-34 10-20 Pressed corned beef, . 51-9 33-8 6-4 2-9 78-42 14-85 12-55 57-7 31-5 7-3 3-5 74-47 17-62 11-91 58-8 25-9 11-8 3-5 62-86 28-64 10-05 Mean of 10, 55-80 29-06 11-54 3-60 66-64 26-10 10-66 Tongue, 64-86 15-35 15-14 2-64 43-64 43-08 6-69 Califoruian salmon (mean of 3), . 61-78 20-16 15-68 2-38 53-42 40-36 8-55 Warden and Bose * analysed a number of representative speci- mens of canned beef and mutton, and compared their results with the figures given by Konig for fresh meat (c/. p. 47). With seven brands of different manufacturers they obtained the following results :— Water, 49-05 to 57-35; fat, 10-34 to 22-08; nitrogen, 3-93 to 4-65; total ash, 0-62 to 4-36; soluble ash, 0-189 to 4-176; chlorine, 0-112 to 2-65; phosphoric acid (PgOj), 0-308 to 0-402 ; potassium oxide, 0-136 to 0-434; sodium oxide, 0-117 to 0-963; extracted by boiling water, 5-35 to 10-414; and nitrogen in boiling water extract, 0-90 to 1-1 per cent. The albuminous substances (N x 6-25) in the anhydrous flesh, freed from all visible fat, are compared in a table with those of fresh meat : — Chemical News, 1890, 71, pp. 291 and 304. 114 FLESH FOODS. Per cent. Albu- minous Substances rage of Canned Beef Samples, . 87-06 ,, ,, Mutton, 87-19 ,, Fresh Cow and Ox Flesh, 93-94 ,, ,, Mutton, 93-81 ,, all Canned Samples, 87-12 „ all Fresh Meat, 93-87 From these analyses Warden and Boss came to the conclusion that the nutritive value of canned meat is considerably less than that of fresh meat, this difference being partially due to the salt which was present in large quantity in some of the canned meats. Sardines in Oil. — In this method of preservation the air is excluded by immersing the fish in olive oil. According to Konig the fish, from which the oil has been removed by pressing it between folds of filter paper, has the following composition (mean of three analyses) : — Water. Nitrogenous Substances. Fat. Ash. 53-64 25-90 11-27 9-00 On the Dry Substance. Nitrogenous Substances. Fat. Nitrogen. 36-49 28-01 6-84 Maljean* gives the following as the composition of sardines, which had been preserved by Appert's process without the use of oil or sauce : — "Water. Nitrogenous Substances. Fat. Ash. 57-60 28-40 8-07 6-03 * Bev. inlernat. des Falsi/., 1894, p. 133. EXAMINATION OF CANNED MEATS. 115 Occasionally a red coloration of sardines, preserved in oil, may be observed. This, according to Auoh^,* is due to a chromogenic bacillus, which is found in large numbers on the sardines before preservation. It is distinct from B. prodigiosus, and is non- pathogenic. The Examination of Canned Meats. — On opening the tins no gas should be found, and the jelly surrounding the flesh should be solid. If liquid, it indicates decomposition. Collection of the Gases. — The method described by Doremus t will be found suitable for the collection and examination of the gases in imperfectly sterilised goods. A hollow, bevelled steel needle is fixed in the upper arm of an adjustable clamp with its point passing through the hole of a rubber cork, which rests upon the top of the can. The upper part of the needle is con- nected by means of a capillary tube with a gas burette or nitro- meter filled with water or mer- cury. The can, which is held between the lower arm of the clamp and the rubber cork, is then punctured by turning the lower screw until the needle pierces the top. The rubber cork makes a tight joint round the needle, and the gases escape gently into the eudiometer, where they are measured and analysed in the usual way. From 60 to 80 c.c. of gas may sometimes be collected. Dore- mus states that when there is a putrid odour, carbon dioxide forms the chief constituent of the mixed gases. In other cases hydrogen predominates, there is no offensive smell, and bacteria are absent, whilst there are indications of the corrosion of the inner metallic surface. Hydrogen has also been found without dis- tinctive signs of corrosion. Occasionally the can is discoloured, as though traces of hydrogen sulphide had been formed, and the reactions of the metals may be obtained with the contents of such tins. * Zeit. Flmch u. Milch Hyg., 1894, p. 135. t Jour. Amer. Chem. Soc, 1897, 19, p. 730. Fig. 18. — Apparatus for oolleoting gases from cans. 116 FLESH FOODS. Tlie Chemical Reaction of Canned Flesh. — According to Utescher* the flesh preserved in cans often has an alkaline reaction, without the flesh being in any way decomposed. This is noticeably the case with canned lobsters, and the point is one of considerable importance, since the alkaline liquid dissolves some of the metal from the interior of the can. To prevent this certain manufacturers line the interior with a silicate enamel, or with tough parchment paper. Poisoning hy Canned Goods.— ¥1001 time to time cases of illness are reported, brought on by eating canned food, though such cases are rare, if the enormous quantities of this class of food annually consumed are taken into account. When they do occur they may be due to decomposition of the flesh, through imperfect sterilisation and the consequent formation of ptomaines {cf. p. 222), or the flesh used may itself have been poisonous, as is sometimes tlie case with fresh meat and, more often, with fish (cf. pp. 217- 220) ; or it may be due to metal from the interior of the can, dissolved by the liquid present, or from careless soldering. Metallic Contamination of Canned Goods. — There appears to be little doubt from the work of various chemists that all kinds of canned articles are liable to metallic contamination, the degree depending to a large extent on the length of time the food has remained in contact with the metal. Van Hamel Koos t in fact advocates that no tins should be employed for the preservation of food without an interior protective lining of some description. The difl^erent metals are tested for by the ordinary quali- tative methods in the ash obtained on calcining portions of the flesh. Tin. — O. Hehner J examined a large number of tinned animal foods, and discovered tin in almost all. In a 1 lb. tin of soup the quantity was 0'035 gramme, and in preserved oysters (1 lb.) 0'04:5. In the case of hard meats the metal was found principally on the surface of the food. In some instances the interior of the can was discoloured or blackened, but in others it was still bright, notwithstanding the fact that an appreciable amount of tin had been taken up by the food. In van Hamel Eoos' communication § the occurrence and significance of this metal in preserved foods is fully discussed, with references to the results of previous workers. Kayser of Nuremberg has recorded cases of poisoning through eating preserved eels which were sub- sequently found to contain 0'19 per cent, of tin, and in * Apoth. Ztg., 1894, p. 765. t Abstract in Analyst, 1895, p. 195. X Analyst, 1880, p. 219. § Apoth. Ztg., 1894, p. 765. PRESENCE 'OF METALS IN CANNED MEATS. 117 a case in whicli 270 soldiers were poisoned by canned lettuces and meat, Bettiuk of Utrecht found from 0'19 to 0*72 per cent, of tin in the food. In a tin of beef eight years old containing 970 grammes, van Hamel Rocs obtained 77 milligrammes of stannic oxide, and all the other articles which he examined were more or less con- taminated. In a can of asparagus thirty-one years old, the coating of tin had been completely dissolved off the metal. Lead. — When this metal is found in canned provisions it is usually derived from the solder of the can. A. Mayer * found in the ash of the meat from three tins of corned beef 0-099 gramme, 0-026 and 0-027 gramme of lead. In the Public Laboratory at Karlsruhe a slice of corned beef 1 cm. thick, weighing 145 grammes, was found to contain 0-09 gramme of metallic particles, whilst 0-01 gramme of lead was found in the ash. Similarly in a tin of ham 0-136 gramme of leaden particles were discovered. In carefully soldered tins of American manufacture, Gautier could not, however, detect any lead in the food, and the chance of its occurrence is considerably lessened by soldering the tin only from ' the outside. Copper. — This may originate from the use of copper vessels in the preparation of the food for canning, or it may have been present as a normal constituent of the food. For instance, Harvey states that in his experience copper is widely disseminated in shell-fish, and that he has always connected the delica1;e pink colour of the ova of salmon with the presence of a very minute quantity of copper. Hehner, too, found a small amount of copper in tinned oysters (c/. p. 68). Baderiological Examination of Tinned Meat. — This is carried out by the general methods given on p. 265. A simple micro- scopical examination is also of considerable importance, and note should be taken whether the muscular fibres still show their cross striations, or whether there is any coloration due to bacteria. If a large number of bacteria are observed it is probable that old or diseased flesh was used, and the presence of poisonous substances (toxalbumoses) is then not improbable. Potted Meats. — The following results were obtained by Konig and SSllscher t in the analysis of difierent varieties of food pastes and potted meats manufactured by Crosse & Blackwell in 1884, * Kbnig, Die Menschlicken Nalir. u. Genuasm., ii. p. 155. t Loc. cit., i. p. 233. 118 FLESH FOODS. with the exception of the pdte de foie gras, which was procured from Strassburg : — ■ Water. Nitrogenous Substances. Fat. Nitrogen- free Extractives. Ash. Sodium Chloride. Pate do foie gras. Potted beef. Potted ham. Potted tongue, . Potted salmon, . Potted lobster, . Anchovy paste, . 46-04 32-81 25-57 41-52 37-64 51-33 36-81 14-59 17-17 16-88 18-46 18-48 14-87 12-33 33-59 44-63 50-88 32-85 36-51 24-86 1-59 2-67 3-36 0-46 0-70 4-04 5-18 3-11 2-03 6-78 6-71 6-67 4-90 44-09 0-22 5-72 5-98 5-65 0-38 40-10 Preservation by Chemical Antiseptics. Leaving out of the question the antiseptic substances which are employed in smoking and salting flesh preparations (salt, nitre, etc.), the number of chemical agents which have been used as meat preservatives is very large. Fresh meat and fish, potted meat, canned goods, hams, and sausages are often found to have been treated with some antiseptic or other, or with a mixture of several substances, with the object of increasing their keeping qualities. As to the advisability of this practice various opinions have been brought forward on each side. Although a preservative is a lesser evil than incipient putrefaction, there can be little doubt but that the continued use of food containing such substances has an injuri- ous effect on the consumer. Moreover, in the case of meat, it would seem from Bersoh's experiments (c/. p. 122) that the treat- ment of fresh flesh with antiseptics only preserves it superficially, and lulls the purchaser into a false sense of security. From time to time the results of experiments are published showing that this or that preservative does not interfere with the action of the peptic or pancreatic enzymes in artificial digestion experiments ; but such experiments do not show that the secretion of the fluids by the glands in the body is not weakened, or that the absorption of the digested substances by the system is not inter- fered with. Under the present state of aftairs it is possible for a dealer to add what quantity he pleases of these antiseptics, and thus there is considerable reason for the opinion of the majority of the medical men consulted on this subject by the Lancet* that if preservatives are to be allowed in food, it should be made compulsory for the vendor to declare the nature and amount of the compound used. * Lancet, 1897, pp. 50-60. PRESERVATION OF FLESH BY ANTISEPTICS. 119 Kammerer analysed twenty-four varieties of meat preservatives, and found they could be classified into four groups, containing — 1. Common salt and nitre; 2. Sodium sulphate; 3. Boric acid or borax ; and 4. Boras and sodium sulphite. Among the chemical substances which have been used or recom- mended for the preservation of flesh are the following : — Sulphur dioxide, various sulphites, bisulphites, sulphates and bisulphates ; boric acid, and various borates ; fluorides, fluosilicates, fluoborates ; chlorides (besides common salt) ; nitrates of various metals ; alum, lime, sodium carbonate, formaldehyde, chloraldehyde, acetic acid, sodium acetate, benzoic acid and benzoates ; salicylic acid, sodium salicylate, ethylidene, lactic acid, etc. Of these compounds, boric acid and borax, salicylic acid and sul- phites are the most frequently met with. Boric Acid and Borax are very widely employed for increasing the keeping properties of hams and fish. According to Jean,* borated hams are extensively imported into France from England and America. To preserve fish, boric acid is used in the proportion of 2 grammes per kilo.t Mitscherlich has described the toxic effects of boric acid. It is a cumulative poison, and, according to le F^rd, is eliminated from the system but slowly, having been detected in the urine forty or fifty days after it had been taken.* Boric acid does not appear to interfere with the process of peptic digestion, so far as can be con- cluded from artificial experiments. J There have been numerous cases of flesh poisoning in Switzer- land through meat preserved with borates, which have not acted as complete preservatives, but have only masked the incipient putrefaction. § Detection of Borio Acid in Flesh. — Hafelin || recommends the following method : — 10 grammes of the finely divided flesh (freed from fat as completely as possible) are warmed for about one minute with a mixture of glycerin, 2 c.c. ; alcohol, 4 c.c. ; and water (just acidified with HCl), 4 c.c. ; and the liquid filtered and tested with turmeric paper in the usual manner (brown coloration, turning black on addition of ammonia). As a confirmatory test the residue left on incineration may be moistened with sulphuric acid and methyl alcohol, the flame on ignition having a green tint in the presence of boric acid. The Determination of Boric Acid in Flesh. — The following method is recommended by C. Fresenius and G. Popp IT : — Ten * ^v. de Ghim. Ind., 1897, p. 289. t Hehner, Analyst, 1890, p. 221. t Analyst, 1891, p. 126 ; Cripps, ibid., 1898, p. 182. § Jahresber. Nahr. Genussm., 1895, p. 76. II ZeiLFleiscAu. Milch Syg.,lS98,l^. 188. H Ahstra.ct, Anahjst, 1897, p. 282. 120 FLESH FOODS. grammes of the finely divided substance are triturated in a mortar with from four to eight times the quantity of calcined sodium sul- phate, the mass heated on the water-bath, and, when dry, finely pulverised after the addition of more sodium sulphate. It is then digested m 100 c.c. of cold methyl alcohol for twelve hours, with irequent shaking, and the alcoholic extract distilled. As a rule the whole of the boric acid passes over with the alcohol, but it is advisable to repeat the extraction and distillation, using 50 c.c. of methyl alcohol. The distillates are made up to 150 c.c. with methyl alcohol, and the boric acid determined in 50 c.c. by adding 75 c.c. of water and 25 c.c. of pure glycerin, and titrating with N/20 sodium hydroxide solution, with phenol-phthalein as indicator. As soon as a pale rose coloration is obtained more glycerin is added, and if the colour disappears the titration is continued. The number of c.c. of alkali used, multiplied by O'OOSl, gives the quantity of boric acid (HjBOg) in the liquid titrated. If borates are also present in the substance they should be left in the residue from the distillation, and can usually be extracted with methyl alcohol from the mass after incineration. 0. Hehner * mixes the substance with methyl alcohol acidified with sulphuric acid, and collects the boric acid distilling over with the alcohol, in a solution of sodium phosphate of known strength, evaporates the Jiquid to dryness, and weighs the residue. K. Thadd^ef t recommends a gravimetric method, in which the boric acid distilled over with methyl alcohol is fixed and weighed as potassium borofluoride. The distillate is received in a platinum basin containing a 10 per cent, solution of pure potassium hydroxide, and when four successive portions of 10 c.c. of methyl alcohol have distilled over is concentrated to half its volume on the water-bath. An excess of pure hydrofluoric acid is then added, and the evaporation continued until only a faint smell of hydro- fluoric acid is perceptible. When cool, 50 c.c. of a solution of potassium acetate (sp. gr. 1'14) are added, and the basin allowed to stand for one or two hours, its contents being frequently stirred with a platinum rod. The insoluble substance is collected on a weighed filter paper, which has previously been moistened with alcohol and dried at 100° to 110° C. The filter and its contents are washed with alcohol of specific gravity 0'805, of which from 62 to 72 c.c. are usually required, and are then dried at 100°to 110° C. for three hours and weighed. Sulphur Dioxide and SulpMtes. — Sulphurous acid and its salts are very widely employed in the preservation of meat products, and enter into the composition of very many of the meat preserva- * Analyst, 1891, p. 142. t Zeit. anal. Chem., 1897, pp. 568-637. PRESERVATION BY SULPHUR DIOXIDE AND SULPHITES. 121 tives with fanciful names now in the market. They, all have a powerful germicidal action. As to their physiological action various statements have been made. PoUi * found that 8 to 1 2 grammes of sulphites were not injurious to adults, while others found that children could take 1'8 gramme per day without ill effects. On the other hand, 1 gramme of magnesium sulphite has been found in certain cases injurious to women, causing disorders of the stomach (Bematzik and Braun). As an instance of the extent to which flesh preparations are treated with sulphurous acid and sulphites, it may be mentioned that Fischer f found that 50 per cent, of the preserved meat pro- ducts (sausages, etc.) sold in Breslau in 1895 contained sulphites, the quantity of sulphur dioxide in the meat varying between O'Ol and 0'34 per cent. Action of Sulphurous Acid on Flesh. — Sulphurous acid and its salts, especially calcium bisulphite, appear to have a considerable action on muscular fibre, altering the normal condition of the flesh. According to A. Eiche, J this action proceeds at the ordi- nary temperature, and causes changes in the soluble proteid substances. An addition of 1 per cent, of a sulphite to the flesh is not per- ceptible either to the taste or smell. On cooking the flesh the sulphite is only partially decomposed and expelled. Detection of Sulphurous Acid. — To detect sulphur dioxide in flesh H. Kammerer§ places a sample on a moist strip of potassium iodate starch paper, and moistens the flesh with sulphuric acid (free from oxides of nitrogen). In the presence of sulphites a pronounced blue colour is immediately obtained, whilst pure flesh only gives at most a feeble coloration after a considerable time. Salted flesh or flesh containing nitre cannot be tested in this way, since by the action of the sulphuric acid substances are set free (HCl, and nitrous acid from nitrites present in the nitre), which liberate iodine from the iodate. In many cases it is possible to recognise the smell of sulphur dioxide on simply mixing the flesh with dilute sulphuric acid (1 : 8). Kammerer found in the mean 0'0512 gramme of sulphur dioxide, and O'lOlG gramme of sodium sul- phite in 100 grammes of preserved flesh. Estimation of Sulphurous Acid in Flesh.\\ — A weighed quantity of the finely divided flesh is mixed with phosphoric acid, and dis- tilled in a current of steam or carbon dioxide, the distillate being * Ostertag, Sandbuch der FleischbescJiau, p. 530. t Forschungs Ber., 1897, p. 26. t Journ. Pharm. Ohim., 1897. § ForsAungs Ber., 1896, p. 257. II B. Fischer, Jahreaber. Nahr. u. Genussm., 1896, p. 76. 122 FLESH FOODS. collected in an apparatus containing an excess of iodine solution. After the distillation the sulphuric acid in the distillate is precipi- tated with barium chloride in the usual way. According to Fischer, all flesh containing more than 0-1 per cent, of sulphur dioxide must be regarded as injurious to health. Salicylic Acid is one of the constituents of many of the so-called ' meat-preservatives,' although in the case of fresh meat, at any rate, its action appears to be purely superficial. Bersch * placed a portion of the flesh of a recently-killed animal in a concentrated aqueous solution of salicylic acid, and found that after four days the exterior of the meat was perfectly sound, whilst the interior showed unmistakable signs of putrefaction, and contained a large number of micro-organisms. Hence he came to the conclusion that the preservation of fresh raw meat by salicylic acid and other ordinary chemical antiseptics was not practicable. In flesh pre- parations such as sausages and potted meat, in which the salicylic acid can be distributed throughout the mass, its germicidal pro- perties would obviously be more distributed. But on account of its marked taste it cannot be used in such quantity in meat preparations as in some other food substances in which the flavour is concealed. With regard to the influence of salicylic acid on the human subject there are diverse opinions, but it is significant that the Paris Academy of Science forbid even the smallest addi- tion of salicylates to food as being liable to cause injury where any weakness of the kidneys or digestive organs exists. Detection and JSstimation of Salicylic Acid in Flesh. — The finely-divided iiesh is distilled with steam, and the last portions of the distillate tested with ferric chloride (violet coloration). For the estimation the substance is dried, finely pulverised, mixed into a paste with dilute sulphuric acid and extracted with ether. The ethereal extract is evaporated to dryness, and the residue taken up with water and distilled. The free salicylic acid in the distillate is determined by titration with standard alkali, either litmus or phenol-phthalein being used as an indicator. The violet coloration given with iron salts may also be employed for the colorimetrioal estimation of salicylic acid in the final dis- tillate, the colour obtained on the gradual addition of a very dilute solution of ferric chloride being compared with that given by an aqueous solution of a known quantity of the acid. An additional test for salicylic acid is to warm portions of the meat product with methyl alcohol and sulphuric acid, when, in the presence of the antiseptic, the characteristic odour of methyl salicylate will be observed. _* Die Conservirungsmitlel, p. 86. PEESEEVATION BY FORMALDEHYDE. 123 Formaldehyde. — During the last few years this powerful anti- septic has been tried for the preservation of every description of food, and although its application has not been very successful in the case of flesh, it is still met with in various meat preservatives. ' Carnolin,' for instance, consists of a 1"5 per cent, aqueous solution of formaldehyde slightly acidified. The effects of the continued use of ' formalin ' on the human system have not yet been clearly determined, but its power of forming insoluble compounds with proteid bodies, and its harden- ing influence on animal tissues, must of necessity render meat treated by it much less digestible if not altogether uneatable. Mabery and Goldsmith* found that 0'2 gramme of formaldehyde interfered with the artificial peptic digestion of blood fibrin. Effect on Meat and Fish. — E. Ludwig f states that formalin is not applicable to the preservation of meat products. Ehrlich J tried the effect of an 8 per cent, solution of formaldehyde on various food substances. He found that horse-flesh was com- pletely preserved by it, but that the odour developed was so un- pleasant that the meat could not be eaten. Beef treated with the solution was equally preserved, and did not develop this charac- teristic smell, but, on the other hand, the meat was only fit to be eaten for a short time after the addition of the preservative, on account of the chemical changes caused by it. According to Bloxam,§ fish treated with formaldehyde becomes so hard as to be unsaleable, even when the preserving solution only contains 1 part in 5000. The Detection of Formaldehyde. — The finely-divided meat product is mixed with water and distilled, and the distillate tested for the preservative. A very large number of tests have been described, of which the following are a selection : — 1. A drop of milk is added to the distillate, and the mixture poured carefully down the side of a test-tube containing strong sulphuric acid, with a trace of ferric chloride. A blue ring appears at the zone of contact of the liquids in the presence of traces of formaldehyde (but only with traces). Acetaldehyde does not give this reaction (Hehner).ll 2. One drop of a dilute aqueous solution of phenol is added to the distillate, and the mixture added to strong sul- phuric acid, a bright crimson ring appearing at the line of contact, in the presence of formaldehyde. This coloration is perceptible in solutions containing 1 part * Jour. Amer. Chem. Soc, 1897, p. 889. t Zeit. Fleisch u. Milch Eyg., 1894, p. 193. t Hid., 1898, p. 232. § Analyst, 1895, p. 167. II ^bid-, 1696, p. 96. 124 FLESH FOODS. of formaldehyde in 200,000. If more than 1 part in 100,000 be present, a white milky zone appears above the red ring, while in still stronger solutions a pink curd-like precipitate is obtained. Acetaldehyde, under the same conditions, gives an orange-yellow coloration (Hehner).* 3. Nessler's reagent mixed with solutions of formaldehyde gives a brown coloration, or precipitate, which gradually darkens and finally becomes dark grey. This reaction, which is not given by acetaldehyde, will detect a very minute trace of formaldehyde (Mitchell), t i. The distillate floated on an equal volume of a solution of O'l gramme of morphine hydrochloride gives a reddish violet colour in a few minutes, if formalin be present in greater quantity tian 1 : 6000 (Kentmann),4 5. Several drops of a 10 per cent, solution of phloroglucinol are added to 10 ex. of the distillate, the mixture shaken, and a few drops of a solution of potassium hydroxide added. A red colour is obtained in a solution containing as little as 1 part of formaldehyde in 20,000 (Jorissen). § The Estimatien of Formaldehyde. — Owing to its power of com- bining with proteid substances to form insoluble non-volatile compounds, it is practically impossible to determine the exact amount of formalin added to a meat product, and the amount obtainable by distillation decreases with the lapse of time. One of the simplest methods of estimating formaldehyde in an aqueous solution is based on the fact that it combines with ammonia to form hexa-methylene-amine — eCH^O + 4NH8 = (CHj)^^, -I- 6H2O. A known volume of the solution is shaken in a stoppered bottle with an excess of standard ammonia, the bottle allowed to stand for several hours, the Tincombined ammonia distilled over into standard acid, and the latter titrated back. A correction is made for the acidity of the solution previously determined by titra- tion with standard alkali. H. Smith describes a method of determining formaldehyde by oxidation with potassium permanganate, || and Romijn discusses the accuracy of the various methods of estimation, and describes two new processes. IT See also a paper by R. Orchard {Analyst, 1897, p. 4). * Analyst, 1896, p. 96. t Ibid., 1896, p. 98. t Ibid., 1897, p. 106. § Ibid., 1897, p. 282. II Ibid., 1896, p. 148 ; 1897, p. 5. 1[ Ibid., 1897, p. 221. CHAPTER VII. THE COMPOSITION AND ANALYSIS OP SAUSAGES. In this country only two or three kinds of sausages are manu- factured, but on the Continent, and especially in Germany, where the sausage may be regarded as a national dish, there are many varieties prepared by different recipes. German Sausages. — The chief kinds of German sausages, as described by Kbnig * and by Merges,! are : — Red Sausage {Rofhwurst, Buntiourst). — Pork is boiled for about three-quarters of an hour, flavoured with salt, pepper, pimento, etc., and after admixture of not too great a proportion of warm fresh blood, placed in the skins and boiled. The English black puddings have a similar composition. Magenwurst. — This is very similar in composition to rotJitourst, but contains less blood and rather more fat. The sausage mass is finally packed in a cleansed pig's stomach. Zungenwurst is composed of tripe, pig's head, and fat pork from a young pig, finely minced and mixed with a small quantity of pig's liver and some pig's blood. Blutwurst is composed of bacon and pork, sometimes with the addition of heart and kidney, and with or without flour. It is mixed with about an eighth of its weight of fresh pig's blood, and boiled. Lungenhlutvmrst differs from the preceding sausage in contain- ing finely minced lung. Leberwurste, or Liver Sausages, are prepared from pigs' or calves' livers, thoroughly cleansed from blood, and mixed with a certain proportion of lard and pork, and cooked. The constituents and the proportions vary in the different kinds of liver sausage, such as Mecklenburg leberwurst and Brunswick leberwurst. Gehirn, or Brain Sausage, consists principally of calves' brains and pork. * Die Menschlichen Nahr. u. Genussm., ii. p. 161. t WuTst wnd Fleischwaaren Fabrikation. 126 FLESH FOODS. Presskopfwurst is largely composed of pickled and boiled pig's head. Mosaih Sausage is a mixture of pork and beef, with spices, etc. Abfallblutwurst is made from sinews and butchers' refuse, with bacon and pig's or ox blood. SchwarteniDurst and Sulzemourst consist of lightly cooked un- salted ham, together with skin, etc., boiled soft, and a little blood. Brativurst is prepared from fresh raw pork and ham, with salt, pepper, etc., and sometimes contains lemon-peel or cumin, Cervelatwurst is prepared from pork and lard, often with the addition of beef or horse-flesh. This sausage is often coloured with fuchsin. The Italian Salamiwurst is manufactured from beef or pork, and is coloured with red wine. Knacliwurd, or cracking-Sausage, is a hard, smoked sausage, about 15 cm. in length, with the same composition as cervelat- wurst, but differing in the flesh being previously cooked. Its name is derived from the crackling sound on breaking the sausages apart. Knoblauehwurst, or Garlic Sausage, has the same composition as the preceding sausage, with the addition of garlic. Frankfort or Vienna Wiirstchen are small sausages about the length of a finger, composed of raw, lean pork, seasoned with salt, pepper, etc. Erhswurst consists of a mi.xture of beef-fat, bacon, pea-meal, onions, salt, and seasoning. The pea-meal is prepared by a patent process to prevent the development of acidity. These sausages formed a principal part of the rations of the German troops in the Franco-German war. The Table on p. 127, taken from Konig's larger list, gives the composition of some of these varieties of sausages. English Sausages. — The best kinds of sausages sold in this country are prepared from raw meat, suitably flavoured with spices, and frequently incorporated with a small proportion of bread-crumbs. In poorer districts, however, the amount of bread or powdered biscuit often exceeds that of the meat. A remark- able instance of the extent to which this practice has been carried on was revealed in a recent case in the law courts, in which a baker admitted that the sausages from which he made his sausage- rolls contained no meat at all, but were prepared from bread coloured with red ochre, and seasoned. The innumerable varieties of sausages met with in Germany are not manufactured in England, where sausages are usually described by the name of the meat they contain. COMPOSITION OF GEEMAN SAUSAGES. 127 TJl o < xn < t O o o O Ah % o o ^ So lOr-i(^t^l>,r^(MOiiHi-Hir500CO o C0»OCS)t^C0O3CQC-CO(N-*COCOr-l|>-00 CO «■ "^COCNOSCQCOmCOOSiOOl'-.Ol g^ S l^7lOal'^I4J^,Ht^«loo^^cN'No Q COmcoWCNkOCMCQCQM-^l--'^ 2 ai O C a ll t-^Oicooaoim^coost^THcotN i-HipTtiifscNot^m-^oiiOOci TO-^ocot^-^oooiurstDiJo^M S-§ (NCO(MtN-|»OSOO— iOOOCOOOCOOiI>. % (W^j^-os = a-l-5 (100-a-s), or in percentage of the starch-free brat, by 100[(100 - s) - 2-5(100 -a-s)] I =■ 2-5(100- a -«) in which a represents the water actually determined in the sausage and s the amount of starch. If 64 be taken as the percentage of water in the hrat, the factor 64 1-5 becomes 1'78 = : — in the first equation, and 2-5 becomes 2-78 in the second equation. The Specific Gravity. — Kammerer,* finding that the specific gravity of sausages rose or fell according to the amount of water, attempted to approximately estimate this constituent by deter- mining the specific gravity. In practice, however, he found this impracticable, since the space left on expelling some of the water during the smoking and drying became partially filled with air, which interfered with the accurate determination of the density. He gives the following figures as representative specific gravi- ties : — Pork, r0611; beef, r0731; liver and blood sausages, 1-0350-1-0373; Frankfort liver sausage, 1-0266. The Determination of Flour or Starch in Sausages. — In some countries an addition of starch to sausages is altogether forbidden. Thus, in Austria, it is only permissible to add a small quantity to Augsburg sausages, while there must be no addition to other meat sausages. In this country, as there is no regulation on the subject, the cheaper kinds of sausages are frequently composed of a large percentage of bread ; and in a recent police-court case evidence was given by an apprentice to the effect that he had been taught how to make sausages entirely of bread crumbs, coloured and flavoured to imitate meat. Qualitative Test for Starch.- — A thin section of the sausage is tested under the microscope with a drop of iodine solution, or a small portion of the sausage mass is triturated with water, and a drop of the liquid tested. Quantitative Methods of Estimating Starch. — i. Indirect Estima- tion. — An approximate idea of the amount of starchy substance may be formed by deducting from the original substance the amovmt of water -I- nitrogen multiplied by 6-25 -t- fat -(-crude fibre * Report of the Sixth Assembly of Bavarian Chemists, 1887. DETEKMINATION OF STARCH IN SAUSAGES. 131 + mineral matter. The difference gives approximately the N.- free extract. ii. Inversion loith Malt Extract or Diastase. — Medicus and Schwab * use a malt infusion prepared by digesting 5 grammes of malt with 50 c.c. of water for one and a half hours at 20° to 30° C. Twenty grammes of the sausage material are mixed with 20 c.c. of the malt infusion, the liquid made up to 100 c.c, and left for two hours at 40°-50° C, and then for eighteen hours at the ordinary temperature. The liquid is then filtered, the residue well washed, the filtrate boiled, and the coagulated albumin fil- tered off. The dextrins present are inverted by heating the liquid with hydrochloric acid, and the dextrose determined gravimetri- cally or volumetrically with Fehling's solution, a deduction being made for the sugar in the malt extract used. C. Amthor t heats a weighed quantity of the sausage with 95 c.c. of a solution of diastase and 5 c.c. of hydrochloric acid (sp. gr. 1-124) in a stoppered bottle, immersed for three hours in a hot brine bath. The solution is made up to a definite volume, and the sugar determined with Fehling's solution. He makes an allowance of about 1 per cent, for the starch in the pepper and other spices. iii. Inversion of the Starch hy Acids. — According to H. Frick- kinger \ dilute hydrochloric acid does not invert the whoje of the starch in sausages, and he therefore recommends digesting the sub- stance on the water-bath with sulphuric acid (5 per cent.) until no precipitate is formed on the addition of alcohol to the filtered liquid. Konig§ extracts 5 to 10 grammes of sausage with boiling absolute alcohol and ether to remove the fat. The residue is heated in a Eeischauer pres.sure flask for four hours in a glycerin bath (130°-140° C), and when cooled to 90° C. the undissolved matter is separated by filtration and washed. The filtrate is made lip to 200 or 250 c.c, and digested for three hours with 10 to 20 c.c of hydrochloric acid. After nearly neutralising the liquid with potassium hydroxide the sugar in an aliquot portion is determined with Fehling's solution. From the recent experiments of Sherman || the method of extracting the starch with malt infusion or diastase solution must be regarded as the most accurate for the determination of that substance in cereals. iv. Digestion with Potassium Hydroxide. — J. Mayrhoferl" con- siders the following method more simple and reliable than the inversion processes described above. From 60 to 80 grammes * BericMe d. d. Chem. Gesell., xii. 1285. fUep.f. anal. Chem., 1882, p. 356. J Zeit. anal. Chem., 1880, p. 493. § Loc. cit., ii. p. 167. II Abst. Analyst, 1897, p. 19 ; cf. ibid., 1898, p. 218. ^ Zeit. Nahr. Untersuek., 1896, p. 331; Abst. Analyst, 1897, p. 11. 132 FLESH FOODS. of the sausage are heated on the water-Lath with alcoholic potas- sium hydroxide (8 per cent.), which, in the case of pure sausages, dissolves almost everything except a little cellulose. In order to prevent gelatinisation the solution is diluted with warm alcohol, and filtered through a paper or asbestos filter. The insoluble residue, containing the starch when present, is washed with water until the washings are no longer alkaline, then treated with aqueous potassium hydroxide, and the starch solution made up to a definite volume. On adding alcohol to an aliquot portion the starch falls as a flooculent precipitate, which rapidly subsides. This is collected on a weighed filter, washed with alcohol and ether, dried and weighed. In order to avoid a determination of the ash it is advisable to malie the starch precipitation from a weak acetic acid solution instead of from an alkaline solution, since the acetate formed from the potassium carbonate present is readily soluble in alcohol. By this means the starch is obtained quite free from ash. Mayrhofer gives the results of analyses of known mixtures of sausage with pure potato starch, which show that this method is very accurate. V. Colorimetrical Determination. — G. Ambiihl * has devised a colorimetii-ic process, which consists of extracting the starch from the sausage with water, as in Konig's method (p. 131), and comparing the colour produced on the addition of iodine with that given by a solution containing a known quantity of starch under the same conditions. As a test of this method he prepared sausages con- taining 1'57 of wheat flour, and in two determinations found 1'4 and r5 per cent. For a discussion of the applicability of determining starch colori- metrically, see Littleton, Abst. in the Analyst, 1897, p. 73. Determination of the Acidity. — A weighed quantity of the finely divided sausage (25 grammes) is digested three times with successive portions of boiling water under a reflux condenser, the aqueous extracts filtered, and the residue washed. The total filtrate and washings are titrated with decinormal alkali, and the acidity calculated as lactic acid. Kammerer f obtained the following results by this method : — Alkali. Lactic Acid. Eaw Sausage (smoked), .... Smoked Beef, Fresh Pork, c.c. per cent. 8-0 0-720 9-5 0-855 8-0 0-720 4-0 0-360 * Ohem. Zeit., 1895, p. 805. t Report of the Sixth Asscinbly of Bavarian Chemists. DETECTION OF HORSEFLESH IN SAUSAGES. 133 As several micro-organisms are able to produce lactic acid, this gives an additional means of judging as to the freshness of meat preparations, especially when considered in conjunction with the results of a determination of the acidity of the fat (rancidity). A distillation of the volatile acids may also enable one to decide whether the flesh has been smoked, since pyroligneous acid is one of the constituents of wood smoke. The Acid Value of the Pat. — This is determined by the method given on p. 95, and, when the fat is rancid, serves to some extent as an indication of the degree of rancidity. M. Mansfield * made experiments to determine whether the fat towards the exterior of the sausage was more rancid than that in the interior. In one Salami sausage the fat near the outside had an acid value of 34, whilst that of the interior fat was 38. In another the fat through- out had an acidity of 43. The Determination of Gristle in Sausages. — An approximate estimation of the amount of gristle and similar substances may be made by the method described by A. H. Allen, t Twenty grammes of the sausage are disintegrated in cold water and the fragments of gristle removed with forceps (by the aid of a lens), washed with methylated spirit and ether, dried at 100° C, and weighed. The nitrogen which they contain is then determined by Kjeldahl's process, and deducted from the total nitrogen originiJly found in the sausage. The difference (taken as proteid nitrogen) multi- plied by 6'3 gives some idea of the amount of gelatinoid sub- stances. By this method Allen found the following percentages of gristle in different kinds of English sausages : — Pork, 0'67 ; ' Cambridge ' pork, 0-72; Mutton, 3-11 ; German, 1-13; Polony, 0-54.t The Detection of Horseflesh in Sausages.— Reference was made in a preceding chapter (p. 56) to the fact that a large number of the horses slaughtered in Paris are made into sausages, the vendors of which are supposed to declare that horseflesh is present. In Germany and Austria horseflesh is also largely eaten, and a considerable proportion of it is used up in sausages, either openly or surreptitiously. In England the prejudice against the use of horseflesh, the heavy penalty for selling it without a promi- nent notification of its nature, and the fact that there is a ready sale on the Continent for exported broken-down horses, all tend to render its occurrence in English sausages unusual. During the last few years the problem of detecting horseflesh has come into prominent notice, and several methods have been described, and confirmed or modified by subsequent workers. * Zeit. Nahr. Hyg., 1893, p. 393. t Commercial Organic Analysis, iv, p. 2S1. 134 FLESH FOODS. i. Treatment of the Flesh Fibres toith Acetic Acid and tcith Alcoholic Potassium Hydroxide. — Stelzer based a method of detecting horseflesh on the changes in colour which the muscular fibres of different kinds of flesh undergo on treatment with these reagents. Ostertag,* however, found that there was no marked difference between the colours thus obtained with horseflesh and with beef (especially bull's beef), although it was possible to dis- tinguish them both from pork. On treating the flesh with alcoholic potassium hydroxide (20 grammes of KOH in 100 CO. of 70 per cent, alcohol), the muscular fibres of beef and horseflesh turn brown, while pork fibres only become white or grey. But, since horseflesh is only employed fraudulently as a substitute for beef, the test is only of positive value in proving that a sausage consists of pork only. ii. Treaimeid with Formaldehyde. — According to E. Ehrlich,t horseflesh, on treatment with formaldehyde, develops an intense characteristic smell within forty-eight hours resembling that of roast goose flesh, Only in one instance has a faint suspicion of this odour been ob- served in the case of beef, and Ehrlich considers that this difference may give a further means of distinguish- ing between the two kinds of flesh. iii. The Glycogen Reaction. — The occurrence of glycogen in appreciable quantities in horseflesh had often been noted, but it was not until 1891 that Niebel made use of its quantitative determination as a means of distinguishing horseflesh from other kinds of flesh (vide infra, p. 136). Two years later Brautigam and Edelmann \ based a method on the well-known colour reaction which glycogen gives with iodine : — Fifty grammes of the finely-divided flesh are boiled for an hour with four times the volume of water, and dilute nitric acid added to the resulting broth, when cold, with the object of precipitating pro- teid substances and decolorising the liquid. The filtrate is tested with a freshly-prepared saturated aqueous solu- tion of iodine, which is added so as to form a layer on the surface of the liquid. In the presence of glycogen a wine-red ring is formed at the point of contact. When the colour does not appear or is uncertain, the flesh is heated on the water-bath with a solution of potassium hydroxide (3 per cent, of KOH calcu- * Zeil. Fleisch u. Milch Hyg., 1895, p. 184. t Uriel, 1S98, p. 232. t Fharm. Cenlralb., 1893, p. 657. COLORIMETKIC TESTS FOE HORSEFLESH. 135 lated on the flesh) until the muscular fibre is decom- posed. The broth is concentrated to half its volume, the proteid precipitated with nitric acid, and the iodine solution added as before. Brautigam and Edelmann only obtained this reaction ■with horseflesh, and with the flesh of the human fostus and the fcBtus of animals, but never in their numerous experiments with the flesh of the ox, calf, sheep, pig, dog, or cat. They found that they could detect as little as 5 per cent of horseflesh in a mixture, and also that it was possible to employ the reaction for an approximate colorimetrical estimation. This method was tested by M, Humbert,* who ex- amined various kinds of flesh. Of ten specimens of horse- flesh obtained from different dealers in Paris, seven showed the colour very clearly ; in two it was less pronounced, but still clear ; while in the last it was doubtful. In no case was there any coloration with beef, veal, mutton, or pork. Beef-broth left in contact with the iodine for ten days showed no signs of change. The flesh of the ass also gave a negative result, but with that of the mule the reaction was the same as with horseflesh. A mixture of equal parts of horseflesh, beef, veal, mutton, and pork showed the coloration, but it was less pronounced than with horseflesh alone. The results obtained by W. Niebel t were not so favour- able. This chemist considers Brautigam and Edelmann's reaction uncertain, on the ground that glycogen also occurs in the flesh of dogs, cats, and very young calves ; in the livers of cattle, and in meat extract to the amount of 1 '5 per cent. In old sausages composed of horseflesh the reaction for glycogen was always obtained, although that substance would usually be decomposed under such cir- cumstances. A further uncertainty is the fact that dextrins derived from the starch give a similar colora- tion. He maintains that the red colour obtained with iodine is not suflBcient proof of the presence of glycogen, which should be isolated in a pure condition. Neverthe- less, in his opinion, the iodine coloration, and the occurrence of more than one per cent, of grape sugar in the fat-free substance, point to the presence of horse- flesh, even when all the glycogen has been decomposed. In his experience the red colour only fails in the case of the flesh of young foals. * Journ. Pharm. Chim. , 1895, p. 195. t Zeit. Fleisch u. Milch Hyg. , 1895, p. 86. 136 FLESH FOODS. Drechsler came to the same conclusion as Niebel, since in his experiments on the glycogen test he obtained a wine-red coloration with ten specimens of beef. The following modified process was devised by Courlay. and Coremons.* About 50 grammes of the finely-minced flesh are boiled for fifteen to thirty minutes with 200 c.c. of water. After cooling, the broth is filtered, and tested with a few drops of iodine solution prepared by dissolving two parts of iodine and four parts of potas- sium iodide in one hundred parts of water. A brown coloration, disappearing on warming to 80° C, and re- appearing on cooling, indicates the presence of horseflesh. When flour or starch is present, as in sausages, the blue colour may mask the glycogen reaction. This is ob- viated by adding two or three times the volume of C(to- centrated acetic acid to the broth, filtering, and again testing the filtrate with the iodine solution. No reaction was obtained in this way with the flesh of cattle, calves, pigs, dogs, or cats, but this observation did not apply to the flesh of the foetus of any of these animals. T. Bastion t has recently examined these various modi- fications, and has found both the original process of Brauti- gam and Edelmann, and the preceding modification inconclusive. He has made a long series of experiments under varying conditions, and finds that the following slight modification gives the most satisfactory result, and is capable of detecting 5 per cent, of horseflesh, even in the presence of starch. About 20 grammes of the finely divided sausage are boiled for thirty minutes to one hour with 100 c.c. of water, so that the volume of the liquid is reduced to about 30 c.c. When cold the broth is filtered and about 10 c.c. tested with two or three drops of iodine water, or of a solution of iodine, 1 gramme ; potassium iodide, 2 grammes; water, 100 c.c. A fugitive reddish-violet colour is obtained with horseflesh. Care must be taken not to add an excess of the iodine reagent, or the colour will change to reddish-brown. When starch is present, acetic acid is added as in Courlay and Core- mon's modification, iv. The Quantitative Determination of Glycogen. — In Niebel's \ method the flesh is heated on the water-bath for six or eight hours with from 3 to 4 per cent, of potassium * Zeit. Nahr. UnUrsuch., 1896, p. 173. t Jonrn. Pharm. Chim., 1898, p. 540. X Jahresber. Nahr. Genussm., 1891, p. 33. QUANTITATIVE ESTIMATION OF GLYCOGEN. 137 hydroxide, and four times its volume of water. The broth thus obtained is evaporated to half its bulk, and hydrochloric acid and a solution of mercuric iodide in potassium iodide (Briick^'s reagent), added to the cold liquid, to precipitate nitrogenous substances. The clear filtrate is mixed with two and a half times its volume of 90 per cent, alcohol, and the precipitated glycogen collected on a filter, washed successively with 60 per cent., 90 per cent., and absolute alcohol, with ether, and again with absolute alcohol, dried at 110° C, and weighed. If dextrins and dextrose are present as well as glyco- gen, Niebel advocates the use of Landwehr's method. The broth, prepared in the manner described above, is neutralised and freed from albuminous substances by the addition of a little zinc acetate. The filtrate and wash- ings are heated on the water-bath with a sufficient quan- tity of a concentrated solution of ferric chloride, after which a concentrated solution of sodium hydroxide is added, drop by drop, until all the iron is precipitated. The precipitate is rapidly filtered oflT, washed with hot water, and dissolved in concentrated acetic acid. The cold solution, to which hydrochloric acid has been added, until a yellow coloration is obtained, is poured into alcohol, and the fiocculent precipitate of glycogen is collected, washed and dried as described above. When the glycogen has undergone decomposition, as in the case of sausages which have been kept for some time, Niebel converts the whole of the carbohydrates present into dextrose, and determines the total amount of reduc- ing substances in the flesh by means of Fehling's solution. In sausages containing no horseflesh he found not more than 0'7 per cent, of dextrose, while when horseflesh was present the amounts found varied from 1"189 to 3'707 per cent., and in these glycogen could, as a rule, be identified. In the absence of added starch or sugar, Niebel regards the presence of horseflesh as proved when the total amount of carbohydrates (expressed as dextrose) exceeds 1 per cent., calculated on the fat-free dry sub- stance, and when the flesh itself is of a brownish-red colour. Obviously, this method is useless in the case of sausages containing bread or other amylaceous substances. Bujard * regards Mayrhofer's method (p. 131) as more suitable than that of Niebel for the determination of gly- * Forschungs Ber., 1897, iv. p. 47. 138 FLESH FOODS. cogen. The flesh is dissolved in aqueous potassium hydroxide, proteid substances precipitated by means of hydrochloric acid and Nessler's reagent, and the gly- cogen, after precipitation by the addition of alcohol to the clear filtrate, is washed on a weighed filter with dilute alcohol and ether, and dried at 110° C. The results given in Table 1. were obtained recently by this method, whilst those in II. were obtained some time ago by Niebel's method : — Table I. Water. Per Cent. Per Cent. Glycogen Direct. Niebel. Mayrhofer. Horseflesh, ,, ... ,, ... ,, ... Red sausage (Knackwurst), Pork sausage, . Veal Pork, .... 74-44 74-87 76-17 76-00 6926 67-25 74-6 75-0 0-440 0-600 1-827 0-592 0-445 0-620 1-727 0-610 0-038* 0-240* 0-086 0-186 Table II. Per Cent. Glycogen Water. Glycogen. on Dried Substance. Horseflesh, 61-83 0-846 2-24 72-90 0-174 0-64 70-47 1-366 4-62 71-84 0-59 2-09 ,, (smoked), 43-00 0-108 0-19 Beef (ox). 73-62 0-206 0-74 * In these pepper-starch could be detected microscopically, and on testing with iodine only the blue starch reaction could be obtained, whilst in all the other cases the glycogen reaction was marked. UNCEKTAINTY OF GLYCOGEN TESTS FOK HORSEFLESH. 139 Table II. — continued. Per Cent. Water. Glycogen Direct. Glycogen on Dried Substance. Beef, .... 75-55 0-018 0-073 Veal. .... 76-12 0-346 1-44 )) .... 74-47 0-066 0-25 Pork, .... ,, .... 54-05 66-29 trace trace Horse Sausages. Red sausage, . 70-04 0-504 1-68 Liver 67-00 1-762 5-34 Salami, .... 33-60 034 0-05 Sausages. Salami, .... 20-00 trace trace Thuringian, . 12-93 *> ,, ,, ... 29-16 »> " From these results Bujard concludes that only in ex- ceptional cases (where the amount is large) can the glycogen be taken as conclusive of the presence of horse- flesh, especially when the latter is mixed with other kinds of flesh. If we take into consideration the results of these dif- ferent chemists, the reaction of glycogen with iodine and the quantitative determination of glycogen must be re- garded as giving uncertain conclusions as to the presence of horseflesh. Apart from the fact that glycogen appears normally in certain organs of other animals, it has been shown that its formation and distribution throughout the body is influenced by the food given to the animal, and also that the quantity is subject to considerable variation in certain diseased conditions. On the other hand, in old sausages the glycogen may undergo decom- position, and a negative result be obtained with the tests, when horseflesh is actually present. Hence the results obtained by these and similar methods must only be taken as corroborative Evidence. The Form of the Fat Cells. — According to Jungers * the fat cells of the different animals used for food show * Jahresher. N'ahr, u. Genussm., 1894, p. 64. 140 FLESH FOODS. distinct differences in external form, -svhich are especially marked in the case of the horse. This difference can also be observed in the fat cells of apparently fat-Jree flesh, and can be used for the detection of horseflesh in mixtures. In boiled and smoked sausages, however, it is only possible to find unaltered fat cells by taking the test from the centre of the sample. The nature of this characteristic difference is not described. vi. Examination of the Fat. — The fat extracted by one of the methods given on p. 83 is examined by the usual methods, and the results compared with the figures of the constants in the tables on pp. 52-59. Crystallisation from Ether. — When the sausage is com- posed entirely of pork the fat on crystallisation from ether will, as a rule, give the characteristic chisel-shaped crystals. Horse fat, on the other hand, is very soluble in ether, but by using very small quantities of solvent, crystals resembling those of beef stearin (pp. 50 and 58) can be obtained. Iodine Value.- — Since the mean iodine value of beef fat is about 55, whilst that of horse fat is about 83, a determination of this constant is valuable when the sausage is composed of only one of these kinds of flesh, which, however, is not often the case. K. Friihling,* in his experiments on this point, deter- mined the iodine value of the fat from different sausages. The finely divided substance was boiled for a consider- able time with water, and after cooling, the layer of the fat on the surface of the liquid was removed, filtered, and its iodine value determined by Hlibl's method. The results obtained with the fat thus extracted were : — Iodine Value. Sausage made from pure horseflesh 72'5 ,, consisting of horseflesh with ] 5 per cent, of pork, . 62'3 „ >> ,, 50 ,, . 67'^ Since lard has an iodine absorption of from 56'9 to 63'8 (Benedikt), it is obvious that this method would lead to no certain conclusion in the case of mixtures. Examination of the Intermuscular Fat. — The fat within the muscular fibre was first examined by Nussberger.f The fat was extracted from the muscle of various kinds of horseflesh (kidneys, ham, etc.) by means of ether, and iodine values of from 80 to 94 obtained, the mean being • Zeit. angew. Chem., 1896, p. 352. t Chem, FMndscAau, i. p. 61. HORSEFLESH IN SAUSAGES — ^EXAMINATION OF FAT. 141 84. The iodine values obtained were probably too low on account of the presence of other substances, besides fat, extracted by the ether. Bremer * carries Nussberger's method a step further, and determines the iodine value of the more fluid portion of the fatty acids obtained from the intermuscular fat. The sausage mass, from which all visible fat has been removed, is finely minced, mixed with water, and heated for about an hour on the water-bath. The fat rising to the surface is poured away with the water, and the flesh, after having been washed several times with hot water, is dried at 110° C. for twelve hours, and extracted for several hours with a petroleum spirit of low boiling- point. Part of the intermuscular fat thus obtained is used for the determination of the iodine value, refractive index, and Eeichert-Meissl value. The remainder is saponified, the excess of alkali neutralised with acetic acid, and the alcohol evaporated on the water-bath. The soap is dissolved in hot water, the liquid fatty acids separated as zinc salts by Jean's method (p. 98), and the iodine value of the soluble zinc salts, or of the acids liberated from them, determined as described on page 99. The following table gives the results which Bremer obtained : — Iodine value Iodine value of inter- of liquid acids muscular fat. of the fat. 1. Horseflesh sausage without baooii, . . 75'8 108"1 2. , „ with about 6 per cent. ofbaoon 74-0 104-1 3. Horseflesh sausage with about 22 per cent. of bacon well smoked, . . . 53'7 92'4 4. Horseflesh cervelat sausage with about 69 per cent, of bacon, .... 5. Ordinary sausage with some bacon, . 6. Thuringian cervelat sausage with about 65 per cent, of lard, .... 7. Mixture of 1 and 5 in equal parts, . 8. Mixture of 4 and 6 in equal parts, . Bremer also found that when horseflesh was present the petroleum spirit extract had a red to reddish-brown colour, and that even the liquid fatty acids had a more or less pronounced reddish-yellow shade. On the other hand, bull's flesh gave a similar colour, so that this fact can only be used as a confirmatory test. When, * Forschungs Ber., 1897, iv. p. 5. 74-1 57-6 102-1 94-2 64'3 66-4 65-2 95-8 103-1 99-5 142 FLESH FOODS. however, this coloration is obtained, when at the same time glycogen is detected, and when the iodine number of the intermuscular fat exceeds 65, and that of the liquid fatty acids is considerably over 95, there can, in Bremer's opinion, be but little doubt as to the presence of horseflesh. The Artificial Coloration of Sausages. — Sausages are artificially coloured either with the object of concealing an addition of starch or bread, or of improving the colour of the meat, and in some cases disguising its condition. When fresh beef is exposed to the atmosphere it soon changes its colour, and the bright red, due to the oxyhiEmoglobin, becomes dark brown and eventually yellowish- brown or grey. Similar alterations take place in lighter coloured flesh, such as veal and pork, though they are not so pronounced as in beef. When the exposed meat is in the finely-minced state in which it is used for sausages, these changes occur with great rapidity. When decomposition, whether of an acid or alkaline nature (c/. pp. 74-76), has commenced, the surface of the meat often assumes a bluish or greenish tint. On being heated to 70° or 80° C. the haemoglobin of the flesh is decomposed, and hfematin, which has a brown colour, is formed. Hence red flesh (beef, mutton) becomes dark brown on cooking, while the lighter coloured meats {e.g., veal, pork, and fowl), which contain comparatively little haemoglobin, do not show this change in colour, but become grey. In order to regain the original colour many sausage manu- facturers are in the habit of adding a trace of some colouring matter such as cochineal, carmine, or an aniline dye, and this has been a common practice in Germany for the last fifty years. Lately, however, the question has received considerable attention, and there is a growing opinion that since the practice offers great fiicility for disguising unsound flesh, it ought to be altogether forbidden. As an instance in point it may be mentioned that H. Bremer * recently met with a cervelat sausage coloured with carmine, which when cut had all the appearance of sound flesh, but on further examination was found to be quite unfit for food, the acid value of the fat being 76'0. The Microscopical Detection of Colour. — G. Marpmann f recom- mends the following method of examination ; — A section of the sausage, about 1 cm. thick, is thoroughly moistened with 50 per cent, alcohol, and examined under the microscope. When only traces of colouring matter are present, the substance is dehydrated in xylol, which is expelled by means of carbon tetrachloride, and the mass placed in cedar oil. As thus prepared it is transparent, '* Forschungs Ber., 1897, 4, p. 45. t Zeit. angew. Mikrosk., 1895, p. 12. ARTIFICIAL COLORATION IN SAUSAGES. 143 and colouring matters present can readily be recognised. Fuchsin, magenta red, diamond red, carmine, logwood, and orchil stain the cell substance, while acid aniline colours dye the liquid in the cell. In some instances (e.g., with safranin) the colouring matter must be concentrated, and wool or animal tissue placed in the con- centrated solution. The finely divided sausage is digested with 50 per cent, alcohol, the liquid (freed from fat) evaporated to a few drops, and some undyed sausage placed in this solution. The muscular fibres and the fat cells are then stained deeply. Marpmann states that safranin is largely employed for dyeing cervelat sausages. The sausage should also be extracted with ammoniacal water, which is a better solvent than alcohol for many of the colours used as flesh-dyes. Marpmann regards with suspicion all sausages which remain coloured after being kept for two hours in 50 per cent, alcohol, since normal flesh is decolorised under these con- ditions. Action of certain Dyes on Flesh Proteids. — The following table of Marpmann shows the behaviour of different flesh proteids on treatment with certain aniline colours : — Corallin. Eosin. Phloxin. Congo Red. Safranin. Albumin, . Bluish rose. Raspberry red. Raspberry red. Myosin, . ... Peptone, . Orange yellow, afterwards decolorised. Orange pre- cipitate. Decolorised Nucleo-albu- min, Orange. Syntonin, . Reddish. ».» ... Brown. Yeliow. Alkaline Al- buminate, Violet-rose. Reddish. Rose. Yellowish. Fibrin, Red. Rose. Rose, Red. Yellowish red. In addition to alcohol, various solvents have been recommended for the extraction of artificial colouring matter in sausages, such as amyl alcohol, or a mixture of glycerin and alcohol. According to Bremer,* cases are frequently met with in which the artificial colour can be detected microscopically, but cannot be extracted with any of these solvents. In such cases he advocates the use of equal parts of glycerin and water, as recommended by Klinger and Bujard. The finely divided substance is heated for several hours on the water-bath, with two volumes of this mixture * Forschungs Bar,, 1897, p. 216. 144 FLESH FOODS. (slightly acidified), the yellow solution freed from fat and filtered, and the colouring matter precipitated as a lake by the addition of alum and ammonia. On placing the test-tube before the spectroscope, the absorption lines of carmine-lake, lying between b and D, may then be identi- fied. Since the acid solution of the sausage colouring matter is yellow, while carmine-lake gives a red solution with hydrochloric, nitric, and tartaric acids, Bremer suggests that the carmine in such sausages must be present in some other form than lake, possibly combining with the preservative to form a compound insoluble in alcohol. The Action of Nitre on Natural Colouring Matters in Flesh. — In the examination of a number of American sausages, Weller and Riegel * met with three which were of a suspicious colour, and from which the colouring matter could be extracted with glycerin and water, with amyl alcohol, with alcohol and with ether, all the solvents being coloured from light red to dark red. On extracting the meat with acidified glycerin and water, as directed by Bremer, a bright red solution was obtained, but this, when evaporated on the water-bath, after the addition of ammonia, remained unaltered. The colouring matter also dissolved readily in acidified alcohol and amyl alcohol, but on evaporating the solu- tion in contact with wool-fibre, it was not possible to fix the colour on the wool, even in the presence of aluminium salts. Experiments were then made to determine whether any of the salts with which the sausages were strongly impregnated had any effect on the blood-colouring matter, and from the results the conclusion was arrived at that the colouriug matter extracted from these sausages was due to this cause. It was found that flesh containing blood, when dried with sodium chloride, potassium chloride, sodium nitrate, or mixtures of these salts, yielded only minute traces of colour to the solvents. But, on the other hand, deep red solutions were obtained from pig's flesh containing blood, which had been dried with potassium nitrate ; and these behaved in the same way as the coloured solutions obtained from the sausages. The spectroscopical examination showed that the oxy- hemoglobin had undergone alteration, the acidified glycerin solu- tion, diluted with water, giving a spectrum similar to that of methasmoglobin (see p. 39). It was further proved that the alteration of the oxyhaemoglobin was not due to the flesh fibrin being brought into solution by the nitre, and it appeared to be a special characteristic of swine's blood haemoglobin. In one experiment in which calf's blood was dried with nitre, only slight traces of colour could be * Forschungs Ber., 1897, p. 204. DETECTION OF AETIFICIAL COLOURING IN SAUSAGES. 145 obtained after two days' extraction with ether. The fibrin from normal venous blood was found to be readily soluble in a solution of nitre, whereas that from arterial or diseased blood (especially in the case of the ox) was frequently insoluble. From this investigation Weller and Eiegel concluded that Bremer's process (p. 143) is only reliable when the colouring matter can be precipitated from its solution as a lake, and identi- fied chemically or speotroscopically. But since many vegetable colours, which are soluble in water but insoluble in alcohol or amyl alcohol, cannot be precipitated as lakes, Bremer's method, like the others, may often fail. A microscopical examination, too, may be inconclusive when the sausage has been coloured with an aqueous solution of a vegetable colouring matter thoroughly dis- tributed, though in such cases the reactions given by the aqueous extract with ferric chloride, lead acetate, calcined magnesia, man- ganese peroxide, sodium bicarbonate, etc., may give useful indi- cations. Weller and Kiegel regard the official method of the Berlin Police Council (extraction with glycerin and water for fifteen minutes in the water-bath) as useless in the light of their experiments. With reference to these conclusions, E. Spaeth * states that he is unable to confirm their observation on the action of nitre on the colouring matter of the blood. He has made numerous experiments with uncoloured sausages, and only in one, which had been heated with a large quantity of that salt, did the extract show a faint yellowish-red colour. Nitre is often added to pickling beef with the object of pre- serving the natural colour of the flesh. But Serafini t found that even when added in as large an amount as 5 per cent, it had neither antiseptic nor colour-preserving properties. He considered that, taking into account the injurious effects of its continued use, it ought to be forbidden altogether in sausages. Extraction of the Colour with Sodium Salicylate. — E. Spaeth * finds that the ordinary artificial colours used in sausages can be most readily extracted by warming the finely divided substance for a short time on the boiling water-bath with a 5 per cent, solution of sodium salicylate. When a mixture of glycerin and water is used as the solvent it is often necessary to extract hard sausages for hours, and when only a trace of colour has been added it may not even then dissolve. According to Spaeth, aniline colours and carmine are almost exclusively used for colouring sausages, while vegetable colouring matters are but rarely employed. On the addition of ammonia to * Pharm. Centralb., 1897, 38, p. 884. + Jahresier. Nahr. Genussm., 1892, p. 45. 146 FLESH FOODS. the aqueous extract, red precipitates may be obtained, consisting of calcium and magnesium phosphate and possibly aluminum hydroxide, carrying down traces of an aniline colour mechanically. Hence, a further examination of the precipitate is required before the presence of carmine is regarded as proved. For a method of identifying natural and artificial colouring matters alone and in admixture with others, see a paper by Kota in the Analyst, 1899, p. 41. CHAPTER VIII. THE PROTEIDS OP FLESH. Definition. — It is not an easy matter to find a simple and com- prehensive definition for the proteids — the most important of the constituents of flesh. Some of those proposed are cumbersome, and involve the use of long periphrases, while others are inexact. One of the most concise is the recent one of Wroblewski, who describes them as bodies which, on complete decomposition with acids, yield as final products ammonia, nitrogenous organic bases (such as lysine, arginine, etc.), and amido-acids (such as leucine, tyrosine, etc.). This definition, however, is a somewhat arbitrary one, and as it probably excludes the peptones from the class of .proteids, cannot be regarded as altogether satisfactory. Mulder's 'Proteine' Theory. — Mulder found that by the action of potassium hydroxide on the substances we now name ' proteids,' products (albuminates), which he regarded as identical in each case, were obtained. Taking this into account with the fact that the proteids themselves contained the same elements iu nearly the same proportion after deducting the ash, he conceived the theory that these complex nitrogenous constituents of blood, flesh, and other organic tissues and fluids were all compounds of a definite substance with phosphates and other salts. To this sub- stance he gave the name of 'proteine' (irpajretor = pre-eminent), since he regarded it as the primary constituent of all animal tissues. Thus albumin was protein + phosphates + sulphur. „ fibrin „ + „ +2 „ „ hair, horn „ -1- ammonia -1- 3 water, and so on. Liebig and other chemists showed the incorrectness of this theory, and only the name ' proteid ' has survived. Classification of Proteids. — There is too little variation in the elementary composition of different proteids for any scheme of classification to be based upon it, and advantage has therefore been taken of the difiference in solubility of different individuals, 148 FLESH FOODS. and the nature of the products yielded by them on decomposition. Two recent schemes which have much in common are those of Chittenden* and Wroblewski.f In both there are three main groups : — I. Albuminous bodies (Wroblewski), Simple Proteids (Chittenden); II. Compound Albuminous Substances (Wrob- lewski), Compound Proteids (Chittenden) ; III. Albuminoid Sub- stances. In Wroblewski's scheme the albumoses and peptones are placed with the albuminoid substances in the third group, whilst in Chittenden's scheme they are placed in the first group, and enzymes are not included in the classification. The scheme on pp. 150, 151 is based on both these systems of classification, the general arrangement being that of Wroblewski, and the classification according to solubility, especially in the case of the albumoses and peptones, being due to Chittenden. Albuminous Substances. The prott'ids classified in this group are related more or less closely to fresh or coagulated white of egg. They contain carbon, hydrogen, nitrogen, oxygen, and sulphur in only slightly varying proportion. According to Neumeister, the percentage variation is within the following limits : — Carbon. Hydrogen. Nitrogen, Oxygen. Sulphur. Maximum, . ilinimum, . Mean, . 55 50 62 7-3 6-5 7-0 17-6 15-0 16-0 24-0 19-0 23-0 2-4 0-3 2-0 The molecular weights of albuminous substances appear to be very high, from the results of the analysis of their metallic com- pounds and cryoscopic determinations by Eaoult's method. Thus Sabanejeff' assigns to purified egg albumin a molecular weight of 15,000, and Sohiitzenberger gives the formula 02^^113921^15507583 to the same substance. The composition of several of the important members of this group is shown on the next page, upon which is given an * Medical Record, 1894, p. 45. t Berichte d. d. Chem. Gesells., 1898, p. 3045. COMPOSITION OF NATUKALLY-OCCURKING PEOTEIDS. 149 interesting table, showing the percentage composition of some of the more important naturally-occurring proteids, selected from the longer one of Chittenden * : — ■a t3 T3 13 •a T3 n^ p d a R a 13 ri -• d « «; EH s oj d c a CO -T, S a fl a fl 42 >« -»-' o t- CO CO OS CO CD O j__, OS Ash. t- •* 1-1 : Tj* CO i-^ C^ irs rtH CO CO : : CJ OS t^ i-H I-H O .-1 OS -^ Phosphorus. : : ; : : oo oo * ' ■ * A o OS x.-^ CO o -* CO "^ 00 '^ o CO oo CO cs o o Oxygen. CM Oi y~( OS (N (N o -^ 00 CO lO .!>- I-H !>. c^ ^ (M - o 00 o p 4fi p "■31 t-- I^ IC5 CD ■^ rH t^ CO cq 00 xiri r-- o rH ia Nitrogen. O CO i:^ t^ OS I— 1 -^t, CO rH CO 1^ CO Id lO CO U5 CO liO CD CD I-., 00 CO m i-^ CD CD CD t-H I-H rH I-H I-H r-i j-H .— 1 rH rH 1— I-H i-{ I-H iH I-H \n CO 00 1-1 r-f O 00 CO cq 00 Tj< o lo ^_, r^ cq CO Hydrogen. oo Oi I-H r-i O OS OS 00 CO CO oo CD O oo cq m 00 CO CD t^ t^ t^ CD CO CD tN. t^ CD t-- t^ CO !>- CD CO 00 vn rH O O CO CO "^ CO Carbon. o CO rH CO t^ OS CO CO 00 !>. CO CO OS CO CN ■"31 l—i CO (N (M (M CM (M (N cq CO -* o o cq OS -* OS cq irs la »« lO urs ia iCua \a ^a \ri -«e< ITS '^ ITS c a . . a CD a fl ^ ^ &( o o s 1 a B Lacto-albu Myosin, 1 CIS 1 o O Fibrin, . Oxyhsemog Oxyhsemog Mucin, . Nuclein, Casein, . 1 1 § a CL, * Medical Record, 1894, p. 450. 150 FLESH FOODS. CLASSIFICATION Group I. Albuminous Substances. 1. Soluble in water. Coagulable by heat or long contact with alcohol. Albumins : Egg albumin. Serum albumin. Muscle albumin. Plant albumins, etc. InmluMe in water, hut soluble in salt solutions. More or less coagulated by hi-at. Globulins : a. Soluble in dilute and saturated solu- tions of sodium chloride. Vitellins. b. Soluble in dilute solutions of sodium chloride, but precipitated on satura- tion with that salt. Egg globulins. Serum globulins. Lacto-globulin. Cell globulins. Fibrinogen. Myosin, etc. 3. Insoluble in water and salt solutions. Soluble in dilute alcohol. Albuminous substances chiefly of vegetable origin : Zein, Gliadins. 4. Insoluble in water, salt solutions and alcohol. Soluble in dilute acids and alkalies. a. Coagulated by heat, when suspended in a neutral fluid. Acid albumins : Syntonin, and the like. Alkali albumins : Albuminates. b. Not coagulated by heat in a neutral fluid. Glutenins. Insoluble, or nearly so, in water, salt solutio')is,and alcohol. Soluble in strong adds and alkalies, and in acid pepsin and alkaline trypsin solutions. Coagulated albuminous substances : Fibrin. Coagulated white of egg, etc. Group II. Compound Albuminous Substances. 1. Compounds of a proteid with an iron- containing pigment. Soluble in water, and coagulated by heat and alcohol. Haemoglobin. Oxyhsemoglobin. MethEomoglobin. 2. Compounds of a proteid with a mem- ber of the carbohydrate group. In- soluble in water. Soluble in very weak alkalies. Mucins. Mucoids. I. Compounds of a proteid with nucleic acid. Phosphorised bodies yielding on decomposition metaphosphoric acid. Insoluble in water and acid pepsin solution, but more or less soluble in alkalies. Nuclelns. 4. Com.pounds of proteids with nucleins. Very soluble in dilute alkalies. Nucleo-albumina of cell-proto- plasm. Cell nuclei, etc. Caseins. 5. Amyloids. Histonea ? SYSTEMATIC CLASSIFICATION OF PEOTEIDS. OF PEOTEIDS. 151 Group III. Albuminoid Substances. Class I. Structural Substances. Class II. Derivatives of Albuminous Substances. Proteoses, Peptones, etc. Class III. Enzymes. 1. Soluble in boiling water, and yieldirig on decompo- sition leucine and glyco- coll. CoUagenes : Gelatin. Glue, and the like. 2. Insoluble in boiling water. Yielding on decomposi- tion Tnuch tyrosine, with leucine artd glycocoU. Slowly hydrated by boil- ing dilute adds and by pepsin with HCl. Elastins. Insoluble in water, dilute adds arid alkalies, and in add pepsin and alkaZine trypsin solutions. On de- composition yield leudne and tyrosine. Keratins. 14'eurokeratlns. 1. Solitble in water. Not coagulated by heat or alcohol. a. Proto- and Deutero- proteoses : Protoalbumoae. Deuteroalbumose. Globuloses. Elastoses. Myosinoses. &. Peptones: Amphopeptones. Hemipeptones. Antipeptones. 1. Proteolytic: Pepsin. Trypsin. Papayotin, and the like. 2. Am/ylolyti&: Diastase. Invertin, like. 2. Insoluble in water. Soluble in dilute salt solutions. Predpitated by saturation with NaCl. Hetero-proteoses : Hetero-albumoses. Hetero-globuloses. Hetero-myosinoses, etc. 3. Fat- Decomposing En- zymes: Steapsin, and the like. 4. Glucoside ' Decomposing . InsoliMe in water, salt solutions, and alcohol. Soluble in dilute adds and alkalies. Dysproteoses. Antialbumids. 5. Amide - Decomposing Enzymes : Urase, and the like. 6. Coagulating Enzymes: Rennet, and the like. 152 FLESH FOODS. Albumins, of which egg albumin may be taken as the type, are soluble in water, and coagulate on heating. Egg albumin coagu- lates at about 72° C, and has a specific rotation of - 35'5. When white of egg is dried at 100° C. it loses about 88 per cent, of its weight. In preparing ordinary commercial albumin, white of egg is evaporated at a low temperature, leaving light yellow flakes. Or sometimes the fibrin, which is also present in small quantity, is previously removed by beating and filtering through a cloth. Globulins are closely allied to albumins, but differ from them in their behaviour towards salt solutions. They dissolve in dilute solutions of sodium chloride, but are as a rule precipitated by saturating the liquid with sodium chloride or magnesium sulphate. The Vitellins, of which representatives are found in egg-yolk and in the eyes of fish, differ from the globulins proper in not being precipitated by saturation with sodium chloride. Acid Albumins. — These are compounds of hydrochloric or acetic acid with an albumin or globulin. They are produced as the first stage in the hydrolysis of these substances by means of pepsin. Myosin, for example, in the digestive process first forms an acid albumin or syntonin. Like globulins, they are precipitated by saturating their solution with sodium chloride or magnesium sulphate. Alkali Albumins or Albuminates are produced by the action of alkalies on albumins or globulins. They are soluble in alkalies, but not in neutral liquids. Coagulated Albumins. — Under the influence of heat, or long contact with alcohol, or in some cases by the action of enzymes, albuminous substances become converted into a peculiar modifica- tion which is exceedingly insoluble. Types of these are coagulated white of egg and fibrin from fibrinogen. The temperature of heat coagulation varies with the nature of the salts in the liquid and with the concentration of the solution (c/. p. 162). It is curious that coagulation cannot be brought about by boiling a solution of an albuminous substance to which a trace of formaldehyde has been previously added. Compound Albuminous Substances. These consist of proteids, whose molecule is composed of a simple albuminous substance in combination with another sub stance often of a non-proteid nature. Hsemoglobins. — In the hxmoglobins there is a colouring matter group which contains iron (see p. 37). ALBUMINOID SUBSTANCES. 153 Mucins. — Mucins and Mucoids are representatives of compounds of albuminous substances with a carbohydrate. Mucins are found in secretions of various glands and on the skin of the snail. They can be precipitated from their solutions in the absence of salts by means of acetic acid or a mineral acid. The precipitate is insoluble in an excess of acetic acid, a property which is made use of in the separation of mucins from albumins. According to Neumeister they have the following composition : — nitrogen, 11-7 to 12-3; carbon, 48-3 to 48-8; oxygen, 31-3 to 33'6 j and sulphur, about 0"8 per cent. By long-continued boiling with dilute mineral acids, or by the action of superheated steam, mucins are converted into syntonins and eventually peptones, while substances of a carbohydrate nature are liberated (c/. p. 24). Mucoids are closely allied to mucins. They have been isolated in small quantity from the white of birds' eggs, and from the cornea of the eye. Hyalogens are substances which are often grouped with the mucoids. By the action of dilute potassium hydroxide, they are converted into very insoluble substances known as hyalins. Hyalogens are found in the skin of the serpent and in the bladder of the echinococous (c/. p. 243). Nucleins. — The composition of a representative nuclein is given in the list on p. 149. See also p. 6. Albumiuoid Substances. I. — Structural Substances. Collagene is a widely distributed substance, forming, as it does, a principal part of the connective tissue and the organic substance of bone. In iTeumeister's opinion it is probably produced in the animal system by the decomposition and oxidation of albuminous substances. Its mean composition is : — Carbon, 50"75 ; hydrogen, 6'47 ; nitrogen, 17'86; oxygen, 24'32; and sulphur, 0"6 per cent. Collagene, unlike the albimiinous substances, does not yield tyrosine on hydrolysis, the end products of the decomposition brought about by boiling hydrochloric acid being leucine, aspartic acid, glutamic acid, and glycocoU. The sulphur, which it contains, appears to be in a much closer state of combination than is that of albumin. Gelatin. — When collagene or substances containing it are boiled with water, the collagene is hydrated and dissolves in the form of 154 FLESH FOODS. gelatin or glue, the latter being an impure gelatin. The elementary composition of gelatin is shown on p. 149, and the composition of the first products of its hydrolytic decomposition on p. 181. Gelatin is not precipitated by mineral acids, by potassium, ferrocyanide with acetic acid, or by salts of lead or copper. It is, however, precipitated by most of the other reagents for pro- teids. Bromine or chlorine precipitate it quantitatively, and it combines with tannin in the presence of salt to form a char- acteristic insoluble compound (leather). Mercuric chloride pre- cipitates it in the presence of hydrochloric acid. Gelatin undergoes hydrolysis with great readiness. On boiling it for a short time with very dilute acid, or for a long time with pure water, it loses its gelatinising power through its conversion into gelatose. Elastin. — This proteid is the main constituent of the elastic tissue. In the analysis of its elementary composition (p. 149) sulphur is given as one of its constituents, but later analyses of pure elastin have shown that it does not contain sulphur. It can be brought into solution by treatment with superheated steam, or by boiling it for several hours with dilute mineral acids or strong alkali (c/. p. 24). Keratins are found in such parts of the animal system as the hair, horns, nails, and feathers. They contain a large proportion of sulphur (from 3 to 5 per cent.), while the oxygen is less than that of true albuminous bodies. They are remarkably insoluble, but can be brought into partial solution by the action of super- heated steam or by boiling with alkali. II. — Debivativbs of Albuminous and Structural Albuminoid Substances. Proteoses. — This word is used as a convenient generic term for certain products of the hydrolysis of native proteids in which the decomposition, whether brought about by acids, superheated steam, or proteolytic enzymes, has only proceeded to a certain extent. Thus it includes the albumoses, derivatives of albumin ; fibrinoses from fibrin ; caseoses from casein, etc. Not unfrequently, however, all such products are termed ' albumoses,' since the latter have received the most study, and may be regarded as typical proteoses. Albumoses. — For the want of more accurate knowledge we group together under this name a large number of albuminous derivatives with a few characteristics in common. Further sub- division can be effected into groups which behave differently with different solvents ; but proteolysis is not a simple process, and at any given stage of the decomposition each group contains sub- ALBUMOSES. 155 stances with ever-varying composition, until finally, with the con- tinuation of the hydrolysis, the products are gradually broken up into substances of a simpler composition, lower molecular weight, and greater solubility, which can be grouped together as peptones. This is doubtless the reason why in many analyses of meat extracts, peptones have been found by one chemist and not by another. For instance, in methods of analysis in which alcohol is used as the precipitating agent, those products which are most soluble, or, in other words, require the greatest addition of alcohol for their precipitation, are retiu-ned as peptones ; whereas, if satu- ration with zinc sulphate were used, they might be partially precipitated together with the derivatives more closely related to the original proteid, and be classed with the albumoses. Old Nairyes for Albumoses. — Some confusion has also been caused by the fact that formerly all the products of peptic digestion were called peptones. When a differentiation between the higher and lower products had been effected, Kiihne gave to the former the name of propeptones, while Meissner termed them a-peptones. Eventually the name albumoses was adopted by Kiihne. General Properties. — Albumoses differ from native albuminous substances in being much more soluble, and in not being coagu- J3,ted by heat or by alcohol, though they can be precipitated by the latter. They contain less carbon, but more oxygen, and have much lower molecular weights. They are slightly diffusible, while albumin proper is completely indiffusible. Like the native proteids they are precipitated from their aqueous solutions by saturation with zinc sulphate or ammonium sulphate. They can also be precipitated by chlorine or bromine, nitric acid, mercuric chloride, phosphotungstic acid, tannic acid, picric acid (primary albumoses), trichloracetic acid, and less readily by a solution of mercuric iodide and potassium iodide in the pres- ence of hydrochloric acid. Subdivision of Albumoses. — The different albumoses formed in the earlier stages of the decomposition may be grouped under protoalbumoses and heteroalbumoses, which collectively form the primary albumoses. From each group of primary albumoses further hydrolysis, as in the process of peptic digestion, forms deuteroalbumoses, and finally peptones. This is shown in the scheme of Neumeister, representing the action of pepsin and hydrochloric acid,* without reference to the hemi- and anti-groups of the molecule given on the next page. * Lehriuch Physiol. Chem., p. 231 ; cf. p. 180. 156 FLESH FOODS. DiAGEAM OP THE AcTION OP PbPSIN ON PeOTBIDS. Native Proteid. I Syntonin. Protoalbumose. Heteroalbumose (Dysalbumose). I I Deuteroalbumose. Deuteroalbumose. I I Peptone. Peptone. Primary Albumoses. — These are precipitated, though not com- pletely, by neutralising the solution, and saturating it with sodium chloride, which gives a white precipitate, dissolving on heating, and reappearing on cooling. They are also precipitated by nitric acid, while deuteroalbumoses give no precipitate until the liquid has been first saturated with common salt. Other preoipitants for primary albumoses are potassium ferrocyanide with acetic acid, and copper sulphate, though these also sometimes precipitate small quantities of deutero- albumose. Protoaibumoses are soluble in distilled water, and in dilute solutions of salt, and are partially precipitated by saturating an acidified solution with salt. They are also precipitated by mer- curic chloride and by copper sulphate. Heteroalbumoses are insoluble in distilled water, but dissolve in weak solutions of salt. They are precipitated like the globulins by pouring their neutralised solution into a large volume of pure water, or by saturating the solution with sodium chloride. They are also precipitated by copper sulphate and by mercuric chloride (in acid solutions). Dysalbumose. — By being left for a long time in contact with water, or by drying, heteroalbumoses are converted into a peculiar insoluble modification known as dysalbumose, which can be parti- ally reconverted into heteroalbumoses by treatment with dilute acid or sodium hydroxide. Deuteroalbumoses are much more closely allied to the peptones than are primary albumoses. They are soluble in water and solutions of salts, and are not precipitated by saturating their solution with sodium chloride. Nitric acid precipitates them only in the presence of an excess of salt, and the precipitates do not dissolve so readily on heating as those of the primary albumoses. schkotter's albumose. 157 Chittenden * gives the following method of isolating them from the primary compounds in the absence of peptones. The solution is neutralised and saturated with sodium chloride, which partially precipitates the primary albumoses. On adding acetic acid, drop by drop, to the filtrate, the residual protoalbumoses are precipi- tated together with a small amount of deuteroalbumose. From the filtrate from this precipitate the deuteroalbumoses can be obtained in a pure condition by dialysing out the salt and acid, concentrating the liquid, and precipitating the proteid with alcohol. It is not an easy matter to completely precipitate the whole of the deuteroalbumoses in a solution of mixed albumoses, and Kiihne states that long-continued boiling in the alternately neutral and alkaline saturated liquid is necessary. S. Frankel f proposes to separate deuteroalbumoses by means of cupric sulphate, and thus to avoid the difficulty of removing large quantities of salts by dialysis. According to Neumeister, this reagent gives a voluminous precipitate, with a solution of 1 : 500, and a turbidity with a solution of 1 : 1000 of deutero- albumose containing protoalbumose, but gives no sign of tur- bidity with pure deuteroalbumose. On adding a dilute solution of cupric sulphate to the albumose solution, a tough coherent precipitate is formed, while any turbidity left in the solution generally disappears after a few hours. The copper is removed from the solution by adding a hot saturated solution of barium ferrocyanide, until a few drops of the liquid on filtration show only a trace of copper. At this stage the liquid is acidified with acetic acid, warmed, filtered, and the filter washed. Barium ferro- cyanide solution is added, drop by drop, to the filtrate so long as a red precipitate is formed, then barium acetate to remove the sulphuric acid. Finally the solution is concentrated and poured into strong alcohol, and the deuteroalbumose dehydrated with absolute alcohol, and washed with ether. Schrotter's Albumose. — H. Schrotter | isolated from Witte's peptone an albumose, or group of albumoses, in the following manner : — The soluble impurities were extracted with methyl alcohol, and the residue dissolved in water acidulated with sulphuric acid, and treated with zinc dust and sulphuric acid. After several days the liquid was warmed on the water- bath, and, after the removal of the sulphuric acid, filtered, con- centrated, and evaporated in vacuo over sulphuric acid. The residue was exhausted with hot methyl alcohol, the extract con- centrated, and the albumose precipitated with absolute ether. * Medicai Record, 1894, p. 485. + Monatsheft.f. Cham., 1897, p. 433. X Ibid., xiv. p.' 612. . 158 FLESH FOODS. Its composition, making allowance for the ash (0'2 to 0-5 per cent.), was: — Carbon, 50'5 to 51-3; hydrogen, 6'4 to 7-0 ; nitrogen, 16-5 to 17 '1 ; and sulphur, 1-1 per cent. Its molecular weight determined in an aqueous solution by Eaoult's method varied from 587 to 714. For the composition of various albumoses and other proteoses prepared by Kuhne, Chittenden, and their co-workers, see page 181. Peptones. — Schrotter * controverts the generally accepted views as to the formation of albumoses as an intermediate stage in the production of peptones by enzymes. In his opinion both albumoses and peptones are precipitated by saturation with ammonium sulphate, but the former may be readily distinguished by their higher molecular weight, larger percentage of nitrogen, and by the fact that they contain sulphur, which peptones do not. This view of Schrotter's illustrates the general want of agree- ment as to the nature of peptones, different chemists attaching that name to som.e certain group of the hydrolysed proteids, which they regard as more worthy of it than some other. It seems, however, most fitting to reserve the name for the most soluble of the derivatives, which are precipitated by strong alcohol, and are not removed by saturation with zinc or ammonium sulphate, although, even in the latter case, lower deuteroalbumoses may be grouped with the peptones. Composition of Peptones. — The analyses by Chittenden t of peptones from different sources, given on p. 159, do not bear out Schrotter's theory that peptones differ from albumoses in not containing sulphur. General Properties of Peptones. — Peptones are much more soluble than albumoses, or at least the higher albumoses (proto- albumoses), and require the addition of much alcohol to pre- cipitate them from their solution. They are not coagulated by heat, and possess great diffusibility. They cannot be salted out by an addition of zinc or ammonium sulphate, a property which is usually regarded as the distinguishing feature between albumoses and peptones. In the pure state a peptone is a hygroscopic amorphous powder, with a bitter taste. It rapidly absorbs moisture from the air and becomes resinous. In the anhydrous condition it dissolves in water with a hissing noise, and the evolution of a considerable amount of heat. * Monatsheft. f. Chem., xir. p. 612, and xvi. p. 609, t Medical Record, 1894, pp. 486 and 5i6. HEMI- AND ANTI-PEPTONES. 159 Chemical Composition op Representative Peptones. Peptone. Carbon. Hydrogen. Nitrogen. Sulphur. Oxygen. Amphopeptone from ( Blood Fibrin, . ( 48-75 7-21 16-26 0-77 27-01 Hemipeptone from ) Coagulated Egg > 49-38 6-81 15-07 1-10 27-64 Albumin, . . ) Peptone from Hempi Seed, . . . / Antipeptone from ( Casein, . • ) 49-40 6-77 18-40 0-49 24-94 49-94 6-51 16-30 0-68 26-57 Antipeptone from \ Myosin, . , .J 46-26 6-87 16-62 1-16 26-09 Many of the ordinary proteid precipitating reagents are not available for peptones. Thus, they are not precipitated by nitric acid with or without the addition of salt, by acetic acid with potassium ferrocyanide, or by an excess of picric acid. On the other hand, they are precipitated by chlorine or bromine, by tannin from a neutral solution, by phosphotungstic or phospho- molybdic acid, by uranium acetate, by mercuric chloride, and by absolute alcohol (c/. pages 164-176). In the biuret reaction they resemble albumoses in giving purple colorations without warming, whilst albuminous substances give more of a violet colour which only becomes purple on applying heat. Peptones can combine with either acids or alkalies to form salt-like compounds, and appear to form definite compounds with hydrochloric acid. Hemipeptones and Antipeptones. — Of the peptones produced by the hydrolysis of albuminous substances or proteoses, part are capable of being further broken up by trypsin, with the formation of simpler substances, such as tyrosine or leucine. The hemi- group of the original molecule appears to contribute chiefly to these, and they were therefore termed hemipeptones by Kiihne and Chittenden. For a similar reason the other portion of the peptones, which resist the action of the enzyme, received the name of antipeptones. Both kinds are grouped together under the name of ampTiopeptones. Gelatin Peptones. — Under the influence of dilute acids, of digestive, and of bacterial enzymes, or of the continued action of 160 FLESH FOODS. boiling water, gelatin is converted into a much more soluble substance or substances known as gelatin peptone. The gelatin undergoes a change analogous to that which occurs in the digestion of simple albuminous substances, and the resulting product, or series of products, is no longer capable of gelatinising. No method of separating these decomposition products of gelatin from ordinary peptones has yet been devised, although Salkowski has described a number of colour reactions which are said to distinguish the two classes of derivatives from one another (c/. page 162). Eeactions and Physical Properties of Proteids. The Combination of Proteids with Hydrochloric Acid. — It is well known that in artificial digestion experiments the free hydro- chloric acid gradually disappears, and that a further addition of it is required to carry on the process. Cohnheim * has prepared albumoses and peptones according to Kiihne and Chittenden's directions, and has determined the average amount of hydrochloric acid with which each kind can combine at a definite temperature. At 40° C. he found that protoalbumoses (in 2-5 per cent, solu- tion) combined with 4'32 per cent, of their weight of hydrochloric acid, deuteroalbumoses with 5'48 per cent., heteroalbumoses with 8'16 per cent., and antipeptones with 15'87 per cent, in the mean. On varying the conditions of temperature and concentration there was a difference in the amounts of hydrochloric acid added, but there was invariably a constant relation in this respect between the three albumoses and the peptone employed. The amount of hydrochloric acid absorbed can be determined by treating the albumose with a definite quantity of the acid in excess, salting out the compound with ammonium sulphate, and determining the residual acid in the filtrate. But this method is said not to be applicable in the case of deuteroalbumoses and antipeptones. It is noticeable that the order in which these compounds can be arranged as regards hydrochloric acid absorption is not the same as the arrangement according to difFusibility, solubility, etc. Cohnheim suggests that probably albumoses can coinbine with hydrochloric acid in more ways than one, or, in other words, be di-basio. Colour Eeactions of Proteids. — There are numerous colour tests for proteid substances, but as many organic bodies, especially * Zeit. Biol., 1896, p. 489. COLOUK EBACTIONS OF PEOTEIDS. 161 among the aromatic compounds, give similar colorations with the same reagents, they cannot be regarded as absolutely characteristic. The Biuret Reaction. — On adding an alkali to the solution of a proteid, and then, drop by drop, a weak solution (2 per cent.) of copper sulphate, there is no precipitation of copper hydroxide, but the liquid becomes violet. Care must be taken to avoid an excess of copper salt, or the violet colour will be masked by the blue. The name of the reaction is derived from the fact that biuret or allophanamide [(CO)2(NH2)2.NH] gives a similar purple or red colour under the same conditions. It is doubtful, however, whether the colour is produced by the same group in the molecules of biuret and of albuminous substances. If a nickel salt be used instead of copper sulphate, the colora- tion will be yellow or orange. According to Neumeister the reaction will detect one part of a proteid in 10,000 of water, while Hoffmeister gives the limit of sensibility as 1 in 12,000. F. Klug * has based a quantitative method of estimating proteids on the spectroscopic examination of the liquid in the biuret test. Millon's Reaction. — On boiling proteids with a solution of mercuric nitrate containing a little nitric acid, a red coloration or precipitate is obtained. This reaction is also given by aromatic compounds, such as tyrosine, in which only one atom of the benzene group is replaced by hydroxyl : — ^6^*\CH2.CH(NH2).COOH. The reaction is much less pronounced with proteids than with tyrosine, but is probably due to the same group in the molecule. Xanthoproteic Reaction. — On heating proteids with strong nitric acid, a yellow precipitate or colour is obtained from the formation of nitro derivatives. This becomes deep orange on the addition of ammonia in excess. The reaction is also given by many aromatic compounds. Adamkiewicz's Reaction. — When albumin, in as dry a state as possible, is dissolved in glacial acetic acid, and half its volume of concentrated sulphuric acid added to the solution, a violet-red colour is produced either immediately or after boiling for some time. Liebermann' s Reaction. — When certain proteid substances are washed with alcohol and cold ether, and heated with concentrated hydrochloric acid (ri9 sp. gr.), they give a violet coloration. Rimini t has shown that this is due to the presence of traces of vinyl alcohol in the ether. * Cfiem. Centralblatt, 1893, ii. p. 499. t Gazz. Chim. Ital., 1899, p. 390. L 162 FLESH FOODS. Colour Reactions of Albumin and Gelatin Peptones. — Salkowski gives the following table of the colour reactions of albumin and gelatin in solution : — Albumin Peptone. Gelatin. Gelatin Peptone. 1 CO. of Solution + (6 c.c. Acetic Acid + 5 c.c. . Sulphuric Acid), . . Violet. Yellowish. Yellowish. Equal volumes of the Solution + concentrated Sulphuric Acid, . . Dark brown. Yellow. Yellow. Millon's reagent, . . . Keddish. Colourless. Colourless. 5 c.c. of Solution + 1 c.c. of Nitric Acid (sp. gr. 1'2) — boil and add so- dium hydroxide, . . Dark orange. Lemon-yellow. Lemon-yellow. Heat Coagulation of Proteids.— As many of the simple albuminous bodies coagulate at a different temperature, it is often possible to separate them by means of fractional coagulation. For this purpose Halliburton has devised the apparatus shown below. FiQ. 18a.. — Halliburton's apparatus. T, tap for water ; 0, copper vessel with spiral tube ; a and h, inlet and outlet tubes ; t, test-tube with fluid and thermometer. The test-tube containing the solution of the proteids is kept in water at the given temperature for five minutes, while the degree of acidity is kept constant by the addition of dilute (2 per cent.) acetic acid, added from a burette, the right proportion to be HEAT COAGULATION OF PKOTEIDS IN FLESH. 163 added after neutrality being about 1 drop to eacb 3 c.c. ol tbe liquid. Thus, for example, from human blood serum there can be separated in this way fibrinogen, coagulating at 56° C. ; serum globulin at 75° C. ; and three kinds of serum albumin at 73° C, 77° C, and 85° C. respectively. Of other important proteids, egg albumin coagulates at 72° to 73° C, myosin at 56° C, vitellin at 75° C, and heemocyanin at 65° C. J. H. Milroy * has studied the degree of coagulation which the albuminous substances of flesh undergo when heated at different temperatures. In each experiment the finely-divided flesh was heated in a beaker for an hour at temperatures ranging from 50° to 120° C, and the non-coagulated albuminous matter ex- tracted with a solution of ammonium chloride (15 per cent.). On extracting different kinds of flesh, without previous heating with this solution, the following amounts of proteids, calculated on 100 parts of the dry flesh, were extracted : — Fresh beef, 14-0 to 23-5; ham, 9-31; salt beef, 13-66; beef pickled in acetic acid, 5'87 ; calf's brain, 2-77. The difference between the coagulable albumin extracted from the non-heated flesh and from the same flesh heated at difierent temperatures gave the amount coagulated by the heat. PROPORTION OF ALBUMINOUS SUBSTANCES COAGULATED BY HEAT. Temperature. °C. Fresh Beef. Ham. Salt Beef. Beef pickled in Acetic Acid. Calfs Brain. 50 60 70 80 90 to 120 45-95 to 55-10 64-37 „ 74-47 90-66 „ 91-01 99-11 „ 100-0 100-0 45-87 64-25 95-28 99-18 100 63-55 84-04 95-32 100-00 100-00 67-13 88-44 100-0 100-0 100-0 51-99 80-15 84-12 90-26 100-0 In one experiment the fresh unheated flesh yielded to the ammonium chloride solution 22-77 per cent, of coagulable albu- minous matters. On slightly roasting the same flesh the amount extracted from the interior was 13-08 and from the exterior 4-71 to 5-21 per cent., while the quantities obtained from the interior and exterior, after strongly roasting the meat, were 0-13 and 0-11 per cent, respectively. Optical Rotation of Proteids. — All proteids rotate the beam * Archiv Eyg., 1895, xxv. p. 154. 164 FLESH FOODS. of polarised light to the left. The specific rotatory powers of representatives of various groups are as follows : — Egg Albumin, Serum Albumin, . Syntonin from Egg Albumin, Sodium Albuminate, Protoalbumoses, (various sources) Deuteroalbumose, . Heteroalbumose, . Fibrinogen, . WD. -33-5° -56 -63-12 -55° -71-40° to -79-05 -79-11 -68-65 -43 Authority. Hoppe-Seyler. )y Haas. Kuhne and Chittenden.* J' )» Hermann. Hoppe-Seyler t has devised a polarimetrical method of quanti- tatively estimating proteids, based on the difference in their rotatory power. The Precipitation of Proteids by Various Eeagents. Precipitation of Proteids -with Alcohol. — All proteids are insoluble in alcohol, and can be precipitated from their aqueous solutions by adding it in sufficient quantity. When albuminous bodies are precipitated by dilute alcohol they are apparently unaltered, but when the alcohol is concentrated and its action continued for some time, coagulation takes place, and the pre- cipitate will not subsequently dissolve in water. Alcoholic precipitation is often used as a means of separating the proteid constituents of meat extracts (c/. p. 199). All such methods appear to depend on the fact that the further the hydrolysis of a given proteid has proceeded the more soluble become its products, and the greater the amount of alcohol required for their precipitation. Hence by varying the strengths of alcohol the proteid nitrogen might be subdivided in many different ways. Precipitation of Proteids by Saturation of their Solutions with Salts. — It is often possible to effect a more or less complete separation of a proteid or group of proteids from its solution by saturating the liquid with a readily soluble salt, and this has been largely used in the quantitative analysis of proteid substances. In such cases the precipitation is probably brought about merely by a withdrawal of the water required for the solution of the proteid, and is not due to the formation of a definite compound between the metallic salt and the proteid, as in the precipitations in Schjerning's method of analysis. The characteristics of the proteids thus ' salted out ' remain unchanged. Certain proteids, such as peptones and some deuteroalbumoses, are soluble in con- centrated solutions of ammonium or zinc sulphate. * Zeit. Biol., xx, p. 11. t Firchow's Archiv, xi. p. 547. THE 'SALTING OUT' OF PKOTEIDS. 165 Saturation with Ammonium Sulphate. — For years this was the method generally employed for the separation of albumoses. The liquid was boiled and filtered to remove coagulable albuminous substances, and an excess of ammonium sulphate added to the filtrate when cold. The precipitate was collected, washed with a saturated solution of ammonium sulphate, boiled in water with barium carbonate to expel the ammoniacal nitrogen, and the residual nitrogen estimated by Kjeldahl's method. Saturation with Zinc Sulphate. — Precipitation with ammonium sulphate suffers from the great drawback of the introduction of nitrogen during the precipitation, and the necessity of removing this before the proteid nitrogen of the precipitate can be estimated. To avoid this, Bomer made experiments with zinc sulphate as a precipitant, and found that it precipitated practically the same amount of proteid nitrogen. Subsequently, in conjunction with Baumann,* he made parallel experiments on the two methods of saturation to determine to what extent nitrogenous bases, amide bodies, and ammonia were precipitated in each case. The results showed that ammonium sulphate precipitates considerable quanti- ties of tyrosine and leucine. With zinc sulphate, on the other hand, ammonium salts, asparagine, leucine, tyrosine, and kreatine, in the degree of concentration in which they occur in meat extracts, are not precipitated, or, at most, the amount of the precipitate is so small as to be negligible. The precipitation is most complete after the addition of dilute sulphuric acid (1:4) in the proportion of 1 part to 50. Magnesium Sulphate. — In Schjerning's opinion it is probable that all readily soluble sulphates would precipitate all albumins and albumoses if added to saturation in the presence of a little acetic acid. In his method of analysing proteid substances, magnesium sulphate is used in place of zinc or ammonium sul- phates as the saturating agent (c/. p. 173). Saturation with Sodium Chloride. — By means of this salt albumoses can be subdivided into two groups — primary proteoses, which are precipitated on saturating their neutral aqueous solution with sodium chloride, and secondary proteoses, which are only partially precipitated on the addition of nitric acid to the pre- viously saturated solution (see pp. 156-157). The Precipitation of Proteids by Metals in Relation to the Periodic Law. — Schjemingt has recently shown that salts of analogous metals precipitate practically the same amount of nitrogen from solutions of mixed proteids, whereas the metals of non-analogous series show a marked difference in this respect. * Zeit. Unters. Nahr. Genussm., 1898, p. 106. t Zeit. anal. Chem., 1898, p. 73. 166 FLESH FOODS. Parallel determinations were made on the lines of his general method (p. 171), with solutions of diastase, peptone, egg albumin, milk, and beer, and the following were the mean results obtained throughout the series : — Nitrogen per cent, precipitated by Chlorides. Acetates. Sulphates. j3 tig Hi .3 a 1 ■3 ■g cO Man- ganese. (MnO) .1 IS o 5-1 6-4 63-0 60-8 4 -8 40-0 38-2 35-5 37-5 44-3 43-4 The results obtained with chromium acetate were much too low, but Schjerning accounts for this on the ground that the complete analogy between chromium and iron is doubtful Although copper salts have some analogies with salts of the magnesium group, precipitation with copper sulphate gave very much lower results, either with or without saturation. For example : — Magnesium. Copper. Iron. Beer, . Egg Albumin, 17-4 94-8 4-5 81-3 82'8 From this it is evident that the sulphates of copper and iron precipitate almost the same amounts of proteid nitrogen. With the acetates of lead, copper, and mercury, which form a naturally ascending but not analogous series of metals, the follow- ing percentages of nitrogen were precipitated : — Lead Acetate. Copper Acetate. Mercuric Acetate. Cold. Boiling. Cold. Boiling. Beer, Wort, 16-0 20-8 19-9 20-8 25 '4 24-3 40-1 47-0 43-5 46-3 With regard to the influence of the acid, it was found that for THE PRECIPITATION OF PEOTEIDS. 167 the same metal the acetate precipitates more nitrogen than the sulphate, and the sulphate more than the chloride. With the latter, the largest precipitation took place in the cold solution ; with the other salts, on boiling. The acetates of calcium and strontium precipitated respectively 84'4 and 85'4 per cent, of the nitrogen of egg albumin. Generally speaking, the precipitating power of metals appeared to increase with their atomic weight in the analogous series. The salts of noble metals are unsuitable as precipitants, chiefly on account of the readiness with which they are reduced to the metallic state. Schjeming gives the following summary with regard to the suitability of metallic salts as precipitating agents. 1. The sulphates and chlorides precipitate at most true albumin, and that often incompletely. 2. The acetates of the magnesium group, and of the extended magnesium group, precipitate only true albumins. The precipi- tating power appears to rise with the atomic weight. 3. The acetate of lead and its analogues (?) precipitate all pro- teids up to the albumoses. 4r. The acetates of the analogous oxides FejOg and Mn^Oj pre- cipitate all proteids up to the real peptones. 5. Uranium acetate and phosphotungstic acid precipitate all proteids, being examples of analogous metals, though of different salts. Uranium acetate can also precipitate some of the ammoniaoal nitrogen in the presence of phosphoric acid, whilst phosphotungstic acid precipitates the whole of it. 6. Mercuric chloride precipitates all the proteids up to the albumoses, or the same amount of nitrogen as lead acetate. Mer- curic acetate precipitates all the proteids, and, in addition, more or less of the amide nitrogen. Precipitation of Proteids with Phosphotungstic Acid. — This reagent is widely employed as a general precipitant for all proteid substances, but the separation is not sharp, and the further the hydrolysis of an albuminous substance has been carried, the less complete is the precipitation. Peptones are only incompletely precipitated, while, on the other hand, certain flesh bases, such as kreatine and kreatinine, are completely precipitated. Mallett * classifies the proteid and amide bodies of commonly occurring food substances into three groups as regards their be- haviour with phosphotungstic acid. 1. Those which, even in fairly strong solution, give no precipi- tate, e.g., leucine, asparagine, aspartic acid, and tyrosine. 2. Those which are precipitated in strong solutions, the pre- * Abst. Analyst, 1898, p. 329. 168 FLESH FOODS. cipitate dissolving on heating and reappearing on cooling, e.g., glutamine, kreatine, kreatinine, hypoxanthine, camine, and urea. Peptone precipitates coagulate, and partially dissolve on heating. 3. Those which are precipitated, the precipitate not being sensibly dissolved on heating, e.g., egg albumin, fibrin, casein, legumin, globvilin, vitellin, myosin, syntonin, hsemoglobin, albu- mose, gelatin, and chondriu. The precipitates given by certain amide bodies are soluble in hot water to the following extent : — Betaine, 1 in 71 parts at 98-2° C. ; kreatine, 1 in 107 parts at 98-1° C; kreatinine, 1 in 222 at 97'9° C. ; hypoxanthine, 1 : 98 at 97'6° C. ; and camine, 1 in 132 at 98-r C. Methods of Preparing and Using the Reagent. — (1.) From 5 to 10 grammes of phosphotungstic acid are dissolved in 100 c.c. of 2'5 per cent, hydrochloric acid (Mallet). (2.) 120 grammes of sodium phosphate and 200 grammes of sodium tungstate are dissolved in water and the solution made up to a litre. The solution of proteid substance is mixed with dilute sulphuric acid (1:1) and the above solution in equal quantities at a temperature of from 60° to 65° C. After standing for twenty-four hours, the precipitate is collected, washed with sulphuric acid (1 : 2), and the nitrogen it contains estimated by Kjeldahl's method. Precipitation of Proteids by Halogens. — Chlorine Precipitation. — Proteids combine with the halogens, forming insoluble sub- stances. Although this fact was pointed out years ago by Mulder, it had been lost sight of until Rideal and Stewart* described a method of estimating proteids by precipitating them from their solutions with chlorine. In their method, a current of chlorine is passed through the solution, which should contain not more than 0'2 per cent, of proteids, until the precipitate becomes granular and frothing ceases. After standing, preferably for some hours, the liquid is filtered through a hardened Schleicher and Sobiill's filter paper, which has been previously weighed. The precipitate is washed with cold water, dried as far as possible in warm air, and finally, in vacuo, over sulphuric acid. The weight of the chlorine pre- cipitate, multiplied by 0'78, gives the amount of proteid present. In the test experiments described in the original paper, a deter- mination of the nitrogen in the dried precipitate, and multiplica- tion of the results by 5'5 in the case of gelatin, and by 6'33 in the case of the other proteids examined, gave satisfactory results in most instances. It was found that meat bases, such as kreatinine, were not pre- cipitated by chlorine. * Analyst, 1897, pp. 228-235. PRECIPITATION OF PKOTEIDS BY HALOGENS. 169 Bromine Precipitation. — Some experiments were also made by Eideal and Stewart with bromine as the precipitant, and A. H. Allen * suggested the determination of nitrogen in the precipitate without previous drying. The following simplified method was subsequently worked out by Allen and Searle t on these lines : — The solution containing about 1 gramme of the proteid is diluted to 100 c.c, and rendered distinctly acid by the addition of dilute hydrochloric acid. A considerable excess of bromine water is then added, and the liquid stirred for some time. The precipitate is allowed to settle, the supernatant liquid decanted through an asbestos filter, the precipitate washed with cold water, and if necessary with bromine water, or sodium sul- phate solution, and the nitrogen it contains determined by Kjeldahl's method, and calculated into proteid by the factor 6'33 (or 5 "5 for gelatin). Solutions of kreatinine, asparagine, and aspartic acid gave no precipitate with bromine under these conditions, and the precipitate given by ' meat extractives ' extracted from fresh beef with water contained only a very inconsiderable amount of nitrogen. Some of the principal results thus obtained were — - Substance. Nitrogen per cent. Nitrogen Multiplied by Factor. Total in Total in Factor Em- Original Precipitated Original Precipitated Sub- stance. by Bromine. Sub- stance. by Bromine. ployed. Commercial Gelatin, 14-10 14-00 77-5 77-0 V- Gelatin Peptone, . 14-10 13-90 77-5 76-5 Commercial Scale Albu- min, .... 8-80 8-72 66-8 65-2 ^ Syntonin from Scale Al- bumin, 9-86 9-60— 9-76 62-41 60-77— 61-78 Digested Scale Albumin, 8-89 8-81 56-3 65-8 Fresb "White of Egg, . 1-89 1-88 11-96 11-90 ■6-33 Syntonin from Wliite of Egg, .... 189 1-89 11-96 11-96 Peptone from White of , Egg 0-70 0-69 4-43 4-37 Beef Extractives, . 0-33 0-004 2-11 0-03 -' There can be no question as to the value of halogen precipita- tion, since it has been shown, both by Eideal and by Allen, that ' Analyst, 1897, p. 233. -|- Ilid., 1897, p. 259. 170 FLESH FOODS. meat bases are not precipitated (or if so the precipitates are soluble ill dilute acid). Thus we have a means of exactly separating them from albuminous and gelatinous compounds, which has long been a want in the analysis of meat extracts and similar preparations. Notes on Schjerning's Reagents. — tJranium Acetate. — Kowa- lewsky* showed that proteids were precipitated by uranium ace- tate, but that the precipitates were somewhat soluble in water. Albumins and globulins, and, according to Sohjeming, albumoses and peptones, but not amido-compounds, such as asparagine and leucine, are precipitated. The precipitation may be made at the ordinary temperature, but must always be from a neutral or slightly acid solution (see also pp. 173 and 205). The chief pre- caution is to have the uranium solution quite clear and free from basic compounds. Schjerning states that if phosphoric acid be present in the solution in a larger proportion than the proteid, the ammoniacal nitrogen, and possibly a very little of the amide nitro- gen present, are precipitated. Tin Chloride was first proposed as a reagent for proteid preci- pitation by Drechsel t and by Siegfried, t It precipitates about 90 per cent, of the albuminous substances in white of egg, and in Schjerning's method of analysis (p. 171) all proteids precipitated by it are termed albumin I. Lead Acetate. — Berzelius J was the first to point out that albu- min is quantitatively precipitated by basic lead acetate, but only partially by the normal salt. According to Schjerning it precipitates albumins, and proteid compounds not far removed from nuoleins (denucleins). Ferric Acetate § was proposed by Schmidt-Mulheim for the pre- cipitation of albuminous substances and pro-peptones (proteoses). Schjerning found that it precipitated albumins, albumoses, and 'denucleins.' Stutzer's Copper Hydroxide Reagent. — This is prepared by dissolving 100 grammes of copper sulphate in 5 litres of water, adding 2 '5 grammes of glycerin, then a dilute solution of sodium hydroxide until the reaction is alkaline, and filtering. The pre- cipitate is thoroughly mixed with water containing 5 grammes of glycerin per litre, and decanted and filtered, until all alkali has been removed. The residue is triturated with a litre of water containing 10 per cent, of glycerin, until a mud is obtained which can be drawn up into a pipette. It is kept in a well-closed flask in the dark. * Zeit, anal. Chem., xxiv. p. 551. t Serichte, xxiii. p. 3096 and xxiv. p. 418. J Lehrbuch der Chem., ix. p. 43. § Zeit. anal. Cliem., xix. p. 127. ANALYSIS OF PEOTEID SOLUTIONS. 171 This was said to precipitate albumoses, but not peptones or gelatin. But Rideal and Stewart * have shown that a considerable proportion of gelatin is precipitated, and that this is probably not due to any hydrolysis of the latter in the course of manufacture. They consider that the reagent cannot be relied upon to eiFect a separation of albumoses from gelatin, and this is borne out by their results, in which the amount of nitrogen precipitated by Stutzer's reagent is only about half that contained in the albu- moses obtained by saturating the solution with ammonium sul- phate. Nelson's No. 1 Gelatin. Coignet's Extra Gelatin. Swiss Gold Leaf Gelatin, Somatose. Witte's Peptone. Total Nitrogen. Nitrogen in Ammonium Sulphate Precipitate, Nitrogen in Stutzer's Precipitate, 13-8 14-61 14-38 13-72 14-67 13'69 4-09 13-63 5-91 13-92 4-59 12-44 6-64 10-13 4-52 Schjerning's Method of Analysing Proteid Solutions. — From the fact that metals of analogous series precipitated the same amount of nitrogen from solutions of different proteids, while the nitrogen precipitated by metals of non-analogous series is dis- similar, Schjerning came to the conclusion that the precipitates are compounds of the respective metals with definite proteids. To these proteid substances he has given the following provi- sional names, as indicating to some extent their character. From comparison with the results obtained with malt extract he considers that there are two kinds of albumin in milk. Precipitated by, Tin chloride = a Contains the Proteids. Albumin I. Lead acetate Mercuric chloride ( Albumin I. = 6 -! Albumin II. I Deuuclein. /Albumin I. ,, . . , J Albumin II. Ferric acetate =c < cenuolein. I Albumose. Precipitated by, Uranium acetate =0 Magnesium sulphate = e Contains the Proteids. i Albumin I, Albumin II. Denuolein. Albumose. Peptone. (Albumin I. Albumin II. Albumose. ■ AtwXyst, 1897, xxii. p. 230. 172 FLESH FOODS. From these five precipitations, the amount of the difierent proteids or groups of proteids can be calculated, since Precipitate Albumins I. = a ,, II. = fc-[a + (c-e)] Denucleins = c-e Albumoaes = c-b Peptones = d-c The reagents required are : — 1. A solution of tin chloride, prepared by dissolving 50 grammes of tin in a weighed flask containing a sufficient quantity of boiling concentrated hydrochloric acid, and a little platinio chloride. The solution is evaporated down to about 130 grammes, made up to a litre and filtered. 2. A solution of normal lead acetate, containing about 10 per cent, of the salt, and 10 to 12 drops of 45 per cent, acetic acid per litre. 3. A 5 per cent, solution of mercuric chloride. 4. Pure dry ferric acetate. 5. Dilute acetic acid, containing 15 c.c. of 45 per cent, acid in a litre. 6. A solution of pure uranium acetate (about 10 per cent.) free from ammonia. 7. Pure crystallised magnesium sulphate. 8. A solution of ordinary sodium phosphate, containing about 0'4 per cent, of the crystallised salt. 9. Calcium chloride solution (about 10 per cent.). The solution containing the proteids is first diluted, so that 10 CO. contain a quantity of total nitrogen corresponding to about 5 c.c. of decinormal acid. In some cases, when the solution con- tains little or no ash, the addition of mineral matter (solutions 8 and 9) is necessary. This point may be determined by a pre- liminary test : — If the number of c.c. of the proteid solution which correspond to about 10 c.c. of decinormal acid do not, on boiling, completely precipitate the iron from a solution of 0'8 gramme of ferric acetate dissolved in 40 c.c. of dilute acetic acid (reagent 5), and 50 to 100 c.c. of water, the precipitations with tin, lead, and iron must be preceded by the addition of reagents 8 or 9. The Tin Chloride Precipitation. — About 5 c.c. of the tin chloride solution (reagent 1) are added to 25 c.c. of the proteid solution. After stirring well, the beaker is covered with a glass, and left for from 6 to 24 hours. The precipitate is then collected on a filter and washed with cold water. If the proteid solution be poor in ash, 10 c.c. of calcium chloride solution (reagent 9) are added schjerning's method of analysis, 173 before the tin chloride, and the precipitate Tvashed with a cold 1 per cent, solution of calcium chloride. The Lead Precipitation. — To 25 c.c. of the proteid solution is added a sufficient amount of lead acetate solution (reagent 2), the amount varying with different substances. Care must be taken to avoid an excess of the reagent, or part of the precipitate may be redissolved. After adding the reagent, the liquid is boiled, and the precipitate collected and washed with cold water. If the proteid solution contains little ash, sodium phosphate solution (No. 8) is added before boiling, in the proportion of about three volumes to each volume of lead acetate solution used. Since the lead precipitate is somewhat soluble in the precipitating reagent, a correction is necessary. This Schjeming has found experimen- tally to be about 0'15 c.c. of decinormal acid for each 100 c.c. of filtrate and washings. The Mercuric Chloride Precipitation. — Five c.c. of the mercuric chloride solution (No. 3) are added to 25 c.c. of the proteid solution, the liquid allowed to stand for 4 to 24 hours at the ordinary temperature, the precipitate filtered off, and washed with a cold 0'5 per cent, solution of mercuric chloride, and the nitrogen it contains estimated by Kjeldahl's method. The amounts of pro- teids precipitated by lead acetate and by mercuric chloride are identical, but as the latter usually gives more satisfactory results, the lead precipitation need only be used in exceptional cases. The Iron Precipitation. — Ferric acetate (0-8 gramme) is dis- solved in 40 c.c. of dilute acetic acid (reagent 5) and 50 to 100 c.c. of water, the solution being heated to the boiling point. 20 c.c. of the proteid solution are then added, and the liquid again heated to boiling. The precipitate is filtered off' and washed three or four times with boiling water. The filtrate should be quite clear, and if this is not the case, from 15 to 25 c.c. of the sodium phosphate solution (No. 8) should be added immediately after the second boil- ing, the liquid being meanwhile stirred and kept boiling. With practice the right amount of phosphate can be estimated. Twenty c.c. have no injurious effect if these directions be followed, and only in exceptional cases is it necessary to add greater quantities (at most 25 c.c). The Uranium Precipitation. — To 25 c.c. of the proteid solution are added 20 to 25 c.c. of reagent 6, the liquid heated to the boil- ing point with constant stirring, and allowed to stand over night in a dark place. The precipitate is then collected on a filter, and washed with a cold 1 to 2 per cent, solution of uranium acetate. The correction for the solubility of the precipitate corresponds to 0-10 c.c. of decinormal acid for each 100 c.c. of filtrate and washings. 174 FLESH FOODS. The Magnesium Sulphate Precipitation.- — Five or six drops of 45 per cent, acetic acid are added to 20 c.c. of the proteid solution, and the beaker placed in a water-bath kept at 33° to 36° C. From 18 to 20 grammes of finely powdered magnesium sulphate (MgSO^ + YHgO) are added, with constant stirring, and the liquid allowed to stand for thirty minutes to an hour at the ordinary temperature, a stir being given from time to time. The precipitate is then filtered off, and washed with a cold saturated solution of magnesium sulphate containing 4 to 5 grammes of 45 per cent, acetic acid per litre. Some of Schjerning's results of the analysis of solutions of different proteids are shown in the subjoined table, which is com- piled from others given in his various papers on the subject. A minus sign indicates an error in the calculated results, and where it occurs there was none of the given proteid present. Egg Albumin. Serum of Calf s Blood, Witte'a Peptone. -Liebig's Flesh Peptone. Liebig's Meat Extract. Albumin I., „ II., Denuolein, . Albumose, . Peptone, 1. 89-2 1-9 1-2 3-9 27 1. 85-0 2-2 1-6 5-0 1-2 83-4 12-0 2-9 0-3 -1-5 1. 27 8'0 48-5* 0-0 2. 3-0 18-8 12-2 25-4 -3-5 1. 13-6 2-5 8-5 32 1 -1-6 2. 13-9 9'2 33-2* 0-0 107 0-0 10-2 61 11-4 Precipitation of Proteids by Certain Alkaloid Eeagents. — Tannin. — According to Almen a solution composed of 4 grammes of tannin, 8 c.c. of acetic acid (25 per cent.), and 190 c.c. of dilute alcohol (40 to 50 per cent.) gives a precipitate in solutions of albumin, albumoses, or peptones containing 1 part in 100,000, after standing for twenty-four hours. The precipitates are soluble in excess of the reagent. Mallet makes use of tannin in his method of separating amide bodies from proteids (p. 167). Mercuric Iodide with Potassium Iodide, added to a faintly acid solution of mixed proteids, gives a precipitate which, according to Neumeister, is as complete as that given by phosphotungstic acid. Picric Acid in excess gives a precipitate even in very dilute solutions of albumoses. Peptones are not precipitated (Kcinig). Phosphomolybdia acid is sometimes used in place of phospho- tungstic acid. Including Albumin II. ACTION OF FOKMALDEHYDE ON PEOTEIDS. 175 Mercuric chloride precipitates the same amount of proteid nitrogen as lead acetate (see p. 173). Action of Formaldehyde on Proteids. — E. Beckmann* has found that albumin, albuminates, hemialbumoses, casein, gelatin, etc., combine with formaldehyde to form insoluble compounds, whilst peptones are not rendered insoluble by the treatment. The solution, containing about 1 gramme of gelatin or other proteid, is evaporated to dryness with five or six drops of formalin on the water-bath. The residue is moistened with one or two more drops of formalin, and the heat continued for an hour or more. It is then digested two or three times with water at 60° to 70° 0. in order to remove trioxymethylene, and is dried at 100° C. until constant in weight. If necessary, both proteid solution and formalin must be previously neutralised with calcium carbonate, since free acid causes the compound to be more or less soluble. Beckmann states that pure gelatin thus treated is rendered completely insoluble, as is also the gelatose obtained by heating an aqueous solution of gelatin for thirty to thirty-five hours on the water-bath. Gelatin peptone hydrochloride, however, remains completely soluble. He gives the following table of his results obtained with other proteids, the ash being deducted in each case. Per cent. Serum albumin (Merck), 92 2 Egg „ 94-0 Alkaline albuminate (Griibler), dissolved in dilute sodium carbonate solution, . . . . 104 "9 Hemialbumose (Merck), 92 '2 Do., purified by precipitation with ammonium sulphate 97 "8 Albumin peptone hydrochloride (Paal), . . trace Casein (Merck), 93-9 Diastase 21 '8 Tryptone nil For the application of this method to the analyses of commer- cial peptones and meat extracts see p. 199. C. Lepierre,t who has recently studied the nature of the changes brought about by formaldehyde on certain proteid substances, finds that the action is one of dehydration and condensation with the fixation of CHj-groups. 1. Protoalbumoses are rendered insoluble, and the precipitate obtained does not dissolve in hot water, in a 10 per cent, solution of sodium chloride (exclusion of heteroalbumoses), or in sodium carbonate solution. * Forschungs Berichte, 1896, iii. p. 324. t Journ. Pharm. Chim., 1899, p. 449. 176 FLESH FOODS. 2. D enter oalbumoses are not simple substances, but consist of a series of analogous bodies conveniently grouped together. Of these, the members of higher molecular weight, i.e., those approaching most nearly in composition to the protoalbumoses, are rendered insoluble by the treatment with formaldehyde, whilst those of lower molecular weight, approaching the true peptones, are converted into protoalbumoses, and only after long-continued action of the reagent are the latter transformed into insoluble derivatives. 3. True Peptones, in like manner, are converted into sub- stances of deuteroalbumose nature, and these in turn into proto- albumoses. The precipitates of these diiferent compounds are insoluble in cold or boiling water, but when heated in an autoclave for one or two hours at 110° C. are hydrated and rendered completely soluble, the solutions giving the characteristic reactions of the proteids from which the precipitates were derived. The condensed compounds are capable of being digested by acid pepsin, although with less readiness than the proteids before the treatment with formaldehyde. The Decomposition of Proteids. Decomposition of Proteids by Sulphuric Acid. — Like many other complex nitrogenous substances, proteids are unstable, and can be readily broken down into simpler compounds. Thus albumin, for example, when heated with dilute sulphuric acid, is partially converted by hydrolysis into an insoluble substance (anti-albumid), and partially into soluble substances, consisting principally of albumoses and their further decomposition pro- ducts. This cleavage into two distinct kinds of product on hydrolysis is regarded as evidence of the compound nature of the original molecule of the proteid, the two components being termed the hemi and the anti groups. Antialbumid, which was originally named hemi-protein by Schutzenberger, may be taken as typical of the anti-gron-p. In the sulphuric acid hydrolysis of albumin it constitutes about one- half of the resulting products. It is insoluble in dilute acid, but dissolves in dilute solutions of sodium carbonate. When treated with acid pepsin it under- goes but little change, but alkalin trypsin converts it into a soluble peptone, known as antipeptone. The nature of the final products formed in pancreatic digestion serves to distinguish the hemi- from the anti-groups, inasmuch as ACTION OF SUPEE-HEATED STEAM ON PEOTEIDS. 177 the former yield much simpler final substances, being converted into tyrosine and other amide bodies, while in the case of anti- bodies the process of digestion ends with the formation of anti- albumoses and antipeptones. The composition of antialbumids derived from egg albumin and serum albumin is shown in the following analyses of Kiihne and Chittenden * : — Egg Albumin. Serum Albumin. Antialbumid from Egg Albumin. Antialbumid from Serum Albumin. Carbon, . . Hydrogen, Nitrogen, . . 52-33 6-98 15'84 63-05 6-85 16-04 53-79 708 14-55 54-61 7-27 14-31 Decomposition of Proteids by Super-heated Steam. — By heat- ing a simple albuminous substance, such as albumin, in super- heated steam, it is converted more or less into substances of an albumose nature. Chittenden and Meara t obtained two albumose- like substances by heating coagulated egg albumin in a sealed tube at 150°, while sulphur was simultaneously liberated. Neumeister,! in his experiments with fibrin, obtained two distinctive soluble derivatives — atmidalbumin (precipitated by sodium chloride) and atmidalbumose (dr/Mis = steam). The proportion of the two products depends on the duration of heating ; the longer the action of the superheated water is con- tinued the greater being the proportion of atmidalbumose. A certain proportion of peptones and further decomposition products are also found. E. Salkowsk.i§ heated weighed quantities of flesh (freed as completely as possible from fat and sinew) and of fibrin with water at about 130° C. in a small pressure boiler and analysed the resulting solutions. In the four experiments the amounts of albuminous substance and water used were : — 1. 600 grammes of flesh with 2400 c.c. of water for 8 hours at 131° C. 2. „ „ „ „ 120° C. 3. 550 grammes of pressed blood fibrin ,, 133° C. 4. 450 „ ,, ,, 2000 ,, 130° C. * Zeit.f. Biol., xix. pp. 167 and 173. t Joum. Physiol., xv. p. 501. t Zeit. Biol., xxvi. p. 57, and 1898, xxxvi. p. 420. § Ibid., 1897, p. 190. M 178 FLESH FOODS. And the composition of the resulting solutions was : — 1. 2. 3. 4. Dry Substance, grammes, . . 50-25 47-87 69 00 61-73 Organic Substance, grammes. 45-30 42-52 63-55 61-35 Inorganic ,, ,, 4-85 5-35 0-45 0-38 Ash of Total Solids, per cent., 9-85 11-16 0-66 0-62 Nitrogen, ,, ,, 14-61 13-93 16-63 16-62 Nitrogen of Ash-Free Substance, 16-20 15-96 16-74 16-76 Sulphur ,, ,, 0-51 0-53 0-71 0-76 Ratio of Sulphur to Nitrogen, . 1 : 31-70 1:30-20 1 : 23-6 1:22 The amount of flesh and of fibrin dissolved by once heating ■were 38-7 and 58-15 per cent, respectively. And in the case of flesh, one-third of the proteid substances and t-wo-thirds of the mineral passed into solution. The ratio of sulphur to nitrogen was 1 : 31, whilst in the fresh flesh it was as 1 : 16-7, a fact which showed that sulphur was spht off in the process. Atiiiidalbumin and Atmidalhumoses. — Neumeister found the characteristic products of the action of steam on fibrin (atmid- albumin and atmidalbumose) to be very refractory to the action of pepsin and trypsin and putrefactive decomposition, but Salkowski observed no difference in their behaviour in this respect from ordinary proteids. In Salkowski's opinion it is probable that atmidalbumose may be able to replace albumin in food, though he considers that the question cannot be decided by the results of experiments on lower animals. Atmidalbumin appears to be intermediate in its properties between albuminous substances and primary albumoses, and in Neumeister's opinion it is probably albumin hydrated without decomposition. On treatment with sulphuric acid atmidalbumin and atmidalhumoses are hydrolysed to deutero-albumoses, from which it may be inferred that they have a greater molecular weight than the latter. Chittenden* considers that notwithstanding the fact of their being soluble in water, atmidalhumoses are closely related to the antialbumid formed by the action of acids on proteids, and that, like it, they are derived from the araii'-group of the molecule. He gives the following analyses to illustrate the change which is brought about by the action of superheated steam on coagulated * Med. Record, 1894, p. 452. ACTION OF ENZYMES ON PEOTEIDS. 179 egg albumin, together with an analysis of antialbumid for the purpose of comparison : — Atmidalbmnose Atmidalbumose Coagulated precipitated precipitated Antialbumid. Egg Albumin. by sodium by sodium chloride. chloride+acid. Carbon, 52 'SS 55-13 55-04 63-79 Hydrogen, . 6-98 6-93 6-89 7-08 Nitrogen, 15-84 14-28 14-17 14-65 Sulphur, 1-81 1-66 Oxygen, 23-04 22-00 Decomposition of Proteids by Proteolytic Enzymes. I. Gastric or Peptic Digestion. — The enzyme, pepsin, which is contained in the gastric juice acts upon native proteids in the presence of hydrochloric acid, breaking them down into simpler substances. In this process the tendency of the original molecule to cleavage into he mi- and anti-groups is observed, though not to the same extent as in the decomposition brought about by sul- phuric acid. In peptic digestion the albuminous substance (albumin, for example) is first converted into acid albumin or syntonin, which is then split up into primary proteoses or groups of proteoses, collectively called (in the case of albumin) amphoalbumoses. These consist of protoalbumoses and heteroalbumoses, to the former of which the hemi-groups of the original proteid molecule chiefly contribute, while the latter are mainly derived from the anti-group. By the continued action of the enzyme the primary proteoses are further broken down with the formation of a mixture of secondary proteoses (amphoalbumoses). These are termed deutero- albumoses, and, like the primary albumoses, contain representatives derived from the hemi- and the anti-groups. Finally there results a mixture of hemi- and anti-peptones, the former of which are characterised by being readily converted into simpler substances like tyrosine on treatment with alkaline trypsin, while the latter remain unchanged. At different stages of the digestion a certain number of anti- groups of the compound may be split off to form substances of which antialbumid may be taken as the type, and this body, when 180 PLESH FOODS. the digestion is very active, is partially converted into deutero- albumoses and antipeptones. Neumeister * illustrates these changes by the following scheme, in which the relative proportion of hemi- or anti-groups in the hydrolysed derivatives is indicated by darker or fainter lines : — (Hemi-groups Albumin Molectjle. Anti-groups) Protoalbumose (AmpAoalbumose) II Deuteroalbumose {A mphoalbumose) II Amphopeptone Heteroalbumose (Amphoalbumose) II Deuteroalbumose (Amphoalbumose) Amphopeptone Antialbumid Deuteroalbumose (Antialbumose) Antipeptone Owing to the want of accurate knowledge as to the relative size of the molecule, it has not yet been determined with certainty how many molecules of peptone are derived from each molecule of deuteroalbumose. Neumeister,t however, points out that accord- ing to SabanjefF's determinations by Eaoult's method, the mole- cular weight of protoalbumose from egg albumin is about 2400, and that of the peptone from the same source about 400. If this be correct, it would follow that six peptone molecules would be formed from each molecule of protoalbumose, and from the original albumin molecule (about 15,000) there would result some forty molecules of peptone. Hence thirty-four molecules of peptone would be derived from the heteroalbumose. The hydrolysis of other proteids by pepsin gives products analogous to those yielded by albumin. Thus, fibrin yields proto- librinose, heterofibrinose, deuterofibrinose, and amphopeptones ; whilst the proteoses derived from the myosin of muscle are termed protomyosinose and deuteromyosinose. The composition of some of the more important of these derivatives is shown in comparison with that of their parent pro- teids in the following analyses, given by Chittenden. J * Zea. Biol., 1887, p. v. 391. t Lehrbuch der Phys. Chem., 1897, p. 231. t Medical Record, 1894, p. 486. ACTION OF PEPSIN ON PKOTEIDS. PROTEOLYSIS OF COAGULATED EGG ALBUMIN. 181 Parent Proto- Hetero- Deutero- Hemi- Proteid. albumose. albumose. albumoae. peptone. Carbon, 62-33 51-44 52-06 51-19 '49-38 Hydrogen, . 6-98 7-10 6-95 6-94 6-81 Nitrogen, 15-84 16-18 15-55 15-75 15-07 Sulphur, 1-81 2-00 1-63 2-02 1-10 Oxygen, 23-04 23-28 23-81 24-08 27-64 PROTEOLYSIS OF BLOOD FIBRIN. Parent Proto- Hetero- Deutero- Ampbo- Proteid. fibrinose. fibrinose, fibrinose. peptone. Carbon, 52-68 51-50 50-74 50-47 48-75 Hydrogen, . 6-83 6 80 6-72 6-81 7-21 Nitrogen, . 16-91 17-13 17-14 17-20 16-26 Sulphur, 1-10 0-94 1-16 0-87 0-77 Oxygen, 22-48 23-63 24-24 24-65 27-01 PROTEOLYSIS OF MYOSIN FROM MUSCLE. Parent Proteid. Protomyosinose. Deuteromyoainose. Carbon, Hydrogen, . Nitrogen, Sulphur, Oxygen, 52-82 7-11 16-77. 1-27 21-90 52-43 7-17 16-92 1-32 22-16 50-97 7-42 17-00 1-22 23-39 PROTEOLYSIS OF GELATIN. Parent Proteid. Protogelatoae. Deuterogelatose. Carbon, Hydrogen, . Nitrogen, Sulphur, Oxygen, 49-38 6-81 17-97 0-71 25-13 49-98 6-78 17-86 0-52 24-86 49-23 6-84 17-40 0-51 26 02 182 FLESH FOODS. PEOTEOLYSIS OF ELASTIC. Parent Proteid. Protoelastose. Deuteroelastose. Carbon, Hydrogen, . Nitrogen, Sulphur, \ Oxygen, J B4-24 7-27 16'70 21-79 54-52 7-01 16-96 21-51 53-11 7-08 16-85 22-96 It is interesting to note from these results that, in general, the proportion of carbon falls as the hydrolysis proceeds. In the case of gelatin, however, there is no marked difference in the com- position of the parent proteid and its derivatives, while proto- elastose contains slightly more carbon than the elastin from, which it was derived. This is another instance of the many particulars in which these two albuminoids differ from albuminous substances. It is not possible to artificially convert the whole of a given proteid into peptones, as some intermediate products resisting the action of the pepsin are invariably left. Thus, in Chittenden's experiments the largest yield was about 60 per cent., and the average below 50 per cent. The process, which is at first rapid, soon becomes slow, possibly owing to the interference of the products, which in natural digestion may be removed as soon as formed. Experiments were therefore made in which the digestion was carried out in a parchment dialyser, so as to imitate more closely the natural process by removing the soluble products. In no instance, however, was there any marked increase in the yield. From the results of his own experiments and those of others on the living subject, in which, after the digestion of egg albumin for forty-five minutes, it was found that more albumose than peptone had been formed, Chittenden considers that complete peptonisa- tion is not brought aboiit either in natural or artificial peptic digestion, and that the function of the process is to prepare the way for the profounder changes caused by pancreatic digestion. II. Pancreatic Digestion. — The action of the enzyme (trypsin) of the pancreas on proteids is much more pronounced than that of pepsin, from which it also differs in being most active in a slightly alkaline medium (0-5 to 1 per cent, sodium carbonate). A certain proportion of free acid is required by pepsin, but the action of trypsin is arrested by the presence of much hydrochloric acid. By the action of alkaline trypsin natural proteids are rapidly ACTION OF TRYPSIN ON PKOTEIDS. 183 converted into peptones. Primary proteoses are seldom found, the proteid being apparently first converted into deuteroproteoses. Neumeister* gives the following scheme illustrating the changes which albuminous substances undergo in trypsin digestion : — Native Albumin Deuteroalbumoses Amphopeptonea Antipeptone Hemipeptone I Leucine Tyrosine Aspartic Acid Tryptophan, etc. Theoretically, it should be possible to convert the whole of the hemipeptone into crystalline substances, such as leucine, etc., but in practice Chittenden t found that upwards of 50 per cent, remained, even after long-continued digestion. At various stages of the digestion, antialbumids may be split off, ■but this appears to happen less in natural digestion than in artificial digestion carried out in a flask. Where it occurs in the system it must represent a loss of nutriment, since antialbumids are very resistant to further decomposition. In artificial digestion experiments they separate from the liquid in the flask in the form of a gelatinous mass. The amount de- pends on such conditions as the nature of the original proteid and the strength of the solution of trypsin, but under favourable circumstances may be as much as 25 per cent. Chittenden gives the following analysis of myosin antialbumid formed in the trypsin digestion of myosin from muscular tissue : — Carbon, 57'48; hydrogen, 7*67; nitrogen, 13"94; sulphur, 1'32; and oxygen, 19 "5 9. The most important of the characteristic crystalline products of trypsin proteolysis are : Leucine or amido-caproic acid, ^gsXcH - CHg - CH - NHj - COOH. Tyrosine or para-hydroxy-phenyl-a-amido-propionic acid, * Zehriuch Phys. Chem., p. 217. t Medical Eecord, 1891, p. 546. 184 FLESH FOODS. ■which are representative of two distinct groups (fatty acid and aromatic) in the original proteid molecule. Both are formed in considerable quantity in trypsin digestion. Thus, for example, Kiihne found in a typical experiment 9"1 per cent, of the former and 3 '8 per cent, of the latter. They are formed in much larger proportion in artificial digestion than in the natural process in the body. Other crystalline products which have been isolated are, lysine or di - amido - caproic acid (CgHj^NjOj) ; lysatine (CgHjgNg02), a memhcr of the kreatinine group (p. 8) ; aspartic acid or amido-succinio acid (C^H^Oj) ; and glutamic acid (CsH.OJ. Tryptophan or Protein - eliromogen is a curious product of trypsin digestion, and is also formed in the decomposition of proteids by other agents. It combines with chlorine and bromine, forming with either a brilliantly coloured compound, which, in the case of the latter halogen, has been called the 'bromine body.' The analysis of an impure preparation by Stadelmann gave the following results: — Carbon, 49 '00; hydrogen, 5'28 ; nitrogen, 10'99; sulphur, 3'77 ; oxygen, 110"1 ; and bromine, 19-95 per cent. Chittenden * calculates the composition of the tryptophan to be: — Carbon, 61'02; hydrogen, 6'89; nitrogen, 13-68; sulphur, 4-69; and oxygen, 13'71 per cent. In his opinion the evidence all points to its being a synthetical compound, resulting from the union of two or more of the decomposition products of the original proteid, and containing the sulphur which is liberated from the hemi-peptones in their conversion into crystalline products. Identification of the Products of the Digestion of Fibrin Jnj Alkaline Ti-ypsin. — Any unaltered fibrin is removed by slightly acidifying the alkaline liquid with acetic acid and boiling. The neutral filtrate is concentrated on the water-bath, and a portion tested for deuteroalbumoses by diluting it with an equal volume of saturated salt solution and adding acetic acid. Another portion is saturated with zinc sulphate, and the filtrate tested for peptones by the biuret reaction. When present these are precipitated by adding bromine, or, with less exactness, by tannin. When the digestion has proceeded for several days, the solution contains neither coagulable albumin nor albumoses. In such cases the neutralised solution on concentration deposits most of the tyrosin as a crystalline mass. The filtrate, when evaporated further and allowed to stand, yields a further deposit of tyrosine occasionally mixed with leucine, the former crystallising in highly refractive needles, the latter in globular masses. * Medical Eecm-d 1894, p. 548. ACTION OF PAPAYOTIN ON PKOTEIDS. 185 These amido-acids can also be separated by extracting their solu- tion with boiling alcohol, which dissolves only the leucine. The residual tyrosine is purified by dissolving it in warm ammonium hydroxide, reprecipitating it by neutralisation and washing the precipitate with water. Trypsin Digestion of Gelatin. — The products formed in the pan- creatic digestion of gelatin are analogous to these formed in the peptic digestion — viz., protogelatoses, deuterogelatoses, and gelatin peptones. But amido-acids do not appear to be produced, pro- vided all bacterial action be prevented. Native coUagene, the parent substance of gelatin, is not acted upon by alkaline trypsin. III. Papayotin Digestion. — The enzymes secreted by insect- ivorous plants are analogous to animal pepsin and trypsin, and cause a similar decomposition of proteid substances. That con- tained in the juice of the papaw tree, Carica papaya, of Java, is the best known. It is found in all parts of the plant, but is usually extracted by leaving the juice of the unripe fruit imtil the resins deposit, and precipitating the papayotin from the filtrate with alcohol. It differs from pepsin in not acting in hydrochloric acid solution, and from trypsin in being less thorough in its action. In a 0'2 per cent, alkaline solution it is said to hydrolyse from seventy to eighty times its weight of fibrin in a few hours. It has been stated that the conversion effected by papayotin does not proceed further than the formation of various albumoses, but Chittenden * has found that true peptones are formed. Neu- meister has met with substances of the nature of atmidalbumin and atmidalbumose. Cibil's and Antweiler's flesh peptones are both said to be manufactured by means of papayotin. Decomposition of Proteids by Bacteria. — The action of many of the species of bacteria on proteid substances is similar to that of the enzymes, and it is not improbable that such enzymes are pre- sent in the bacterial cells. According to the conditions of the hydrolysis, albumoses, peptones, phenol-compounds, and an im- mense number of simpler substances, among which may be found one or more of the ptomaines (p. 223), are produced. * Amer, Jour. Fhysiol., 1893, i. p. 25. CHAPTER IX. MEAT EXTRACTS AND FLESH PEPTONES. Of recent years the composition, food value, and methods of examining extracts of meat and similar substances have received a considerable amount of attention, which is not surprising consider- ing the number of new preparations continually put upon the market, and the exaggerated statements of efficacy put forward by the vendors of some of these. Manufacture of Meat Extract. — Although the name of Liebig is inseparably connected with a certain class of these products, the great German chemist was not the first who proposed to concen- trate the soluble part of flesh, although he was the first to show how the suggestion might be carried out with commercial success. The first experiments were made in Munich under the direction of von Pettenkofer in 1850-1852, and eventually the manufacture was commenced on a large scale at Fray Bentos in Uruguay. The method originally proposed by Liebig consisted of soaking the finely divided flesh in eight times its weight of cold water, filter- ing the liquid from the insoluble fibre, heating it to coagulate the dissolved albumin, filtering this off, and concentrating the filtrate by evaporation to a syiup. In practice, however, it was found necessary to employ a higher temperature for the extraction ; the flesh, in a fine state of division, was mixed with the requisite amount of cold water (free from calcium sulphate), and the mixture gradually heated to 180° F. Since from 30 to 32 lbs. of lean meat are required to produce 1 lb. of meat extract (freed from albumin and fat), and the amount of lean meat in a cow only amounts to some 300 to 350 lbs., it is obvious that meat extract could not be profitably manu- factured in Europe. The residue left after the extraction of the soluble matter is used as manure (FleischJcnochenmehl), and, when mixed with salts and other substances, has been made into various articles of human food (c/. p. 106). The manufacture of ' Liebig's Extract of Meat ' has been PHYSIOLOGICAL VALUE OF MEAT EXTEACTS. 187 decided by the High Court of Justice to be public property, and there are now several firms, in addition to the original Liebig's Company, which sell a preparation under that name. Beef Tea. — In ordinary beef tea there is generally a fairly large proportion of gelatin, owing to the boiling water acting on the coUagene and rendering a large proportion of it soluble. The mineral salts and meat bases will be even more completely extracted than in the manufacture of commercial meat extracts, and the higher temperature of the water will also cause a large amount of the fibrin to be hydrolysed with the formation of albumoses, and possibly in some cases peptones. Analyses by the alcohol method of various kinds of concentrated beef tea are given on page p. 200. Physiological Value of Extract of Meat. — Water. — In judging of the comparative value of diiferent kinds of meat extracts, the degree of concentration is obviously of primary importance, for the less the quantity of water left, the greater will be the pro- portion of solid constituents. Food Value. — Liebig expressly stated that his extract of meat was to be regarded as a stimulant, like tea or coffee, and not as a food, and his view is in the main confirmed by the experiments of later chemists. Thus, to mention one only of the more recent statements, C. Voit * asserts from the results of his experiments that extract of meat is practically useless as a food. Albumin, — For this reason albumin is removed from the extract, since although it has a definite food value the quantity is too smaU to be of service, and at the same time the value of the pre- paration as a stimulant is reduced. An addition of albumin is made to certain preparations, but can scarcely be regarded as of any material service. Meat Bases. — The meat bases are undoubtedly the most import- ant constituents of meat extract. They have a stimulating action on the heart, increase the secretion of the saliva, and aid the digestive processes. As is mentioned in the description of leucomaines (p. 218), some of the flesh bases act as poisonous alkaloids when taken in large quantity, and to this must probably be attributed the injurious efiects which result from taking beef tea or meat extract in too great excess, t They appear to be of no value as foods, for Rubner J found that kreatinine does not even act like gelatin in saving albumin. Added Meat Fibre. — In several preparations an addition of flesh powder (with or without albumin) is made with the object of * Munich Med. Woch., 1897, 44, p. 219. t See Aitken'a Animal Alkaloids, p. 45. + Zeit. Biol., 1884, p. 265. 188 FLESH FOODS. giving them some definite food value. As this amounts to at most some 8 or 10 per cent., it is obvious that a large quantity of the substance would be required to obtain as much unaltered proteid as is contained in an egg. On the other hand, it has been pointed out that there is nothing to show that flesh powder suspended in meat extract is more digestible than ordinary flesh in the same fine state of division, whilst the amount of flesh bases, the prin- cipal stimulating agents, is correspondingly reduced. Gelatin. — In the commercial process of manufacturing meat extract care is taken to extract the flesh at as low a temperature as practicable in order to prevent the formation of gelatin from the coUagene. In ordinary household beef tea, where this pre- caution is not taken, gelatin forms a considerable proportion of the final product. Although gelatin is not altogether valueless, its food value is of a very differeut order to that of albumin, and if the latter should be removed from meat extracts as interfering with their stimulating properties, much more so should the former. The function of gelatin in the system is to save the albuminous substances which would otherwise be oxidised with the formation of heat, but it is quite incapable of replacing the nitrogen daily lost by the disintegration of the cells of the body. For instance, Vbit* found that a hungry dog lost 5 "3 grammes of nitrogen per day, but by giving it gelatin the daily loss sank to 2'1 grammes. This latter quantity represented the loss from the organic nitrogen of the cell decomposition ; and it was found that by adding that amount of albuminous nitrogen to the gelatin, equilibrium was established. Added Salt. — In analyses of these preparations it is usual to calculate the whole of the chloride into sodium chloride, although the greatest proportion of the naturally occurring chlorides in flesh consists of potassium chloride. In order to calculate the amount of added salt, Allen t makes an allowance of 0'06 per cent, of chlorine as sodium chloride for each unit per cent, of solid matter present, and deducts this from the total chlorine as sodium chloride found in the extract. Liebig stated that no addition of common salt was required, and it is manifest that, like added meat fibre, such an addition must lessen the proportion of meat bases. Fluid Beef and 'Peptones.' Various methods of acting upon meat fibre, so as to convert it into soluble products, have been employed in the manufacture of * Zeit. Biol,, 1884, p. 284. t Commercial Organic Analysis, iv. p. 303. 'PEPTONES' PREPARED BY THE ACTION OF STEAM. 189 fluid beef and the so-called peptones, the intention in each case being to have not only the flesh bases and other extractives of the meat, but also the nutritive part. The Action of Superheated Steam. — By the hydrolysing action of superheated steam, fibrin is converted into substances of an albumose nature. This method was first described by Wohler, who obtained a brown liquid on heating muscular fibre with water for two to three hours in a sealed tube. The nature of the pro- ducts thus formed (atmidalbumoses, etc.) and the changes caused in flesh are described on pages 177-178. Koch's and Kemmerich's ' Peptones' — These are said to be manu- factured by modifications of this process, the collagene being first removed from the flesh as completely as possible. Analyses of these are given on pages 198 and 203. Somatose. — This is a preparation which has met with a consider- able amount of success in Germany. It is said to be manufactured by a steam process, and is classified by Denaeyer with such pre- parations. According to the latter authority* it does not contain true peptones but has a large proportion alkali-albumin (albu- minate). According to an analysis by 0. Hehner, somatose has the follow- ing composition : — Water, 14:'16 ; fat, 0'41 ; total nitrogen, 11'54 ; proteid nitrogen, 10'88 ; albumoses, 62'13 ; peptones, 5'87; meat bases, 3 '50 (factor 6"3) ; ash, 5'26; and difference 8'67 per cent. A. E. Tankard,! using Allen's bromine method, found the com- position of another sample to be: — Water, 14-25; total nitrogen, 10'78; proteid nitrogen, 9'94; alkali-albumin, 2r83; coagulable albumin, 3-40; albumoses, 33-96; peptones, 3-06; meat bases, 2-62 (factor 3-12); ash, 5-30; difference, 15-58. As regards the food value of somatose, F. Massen J states that it has a high nutritive value and can replace albumin in the animal system. When given to anaemic persons it is said to increase the number of red corpuscles and the amount of hsemoglobin. Dr. Priebsch informed the author that in the military hospital in Vienna it has been found of considerable service in the case of patients who were unable to assimilate other food. On the other hand, E. Neumann § states that these con- clusions are not altogether borne out by the results of his ex- periments. * La Composition des Peptones de Viande, 1896, p. 5. t Allen's Commercial Organic Analysis, iv. p. 384. J Zeit. Urdersuch. Nahr. Oenussm., 1898, p. 260. § Mvmich Med. Woch., 1898, pp. 72-76 and 116-119. 190 FLESH FOODS. ' Pejitarnis.' — This is a preparation manufactured by the Liebig's Extract of Meat Company, and is probably the same as Kemmerich's original peptone. The manufacturers state that its composition is : — -Water, 28"95 ; gelatin, 3'92 ; albumin, 1'85; albumoses, 23'42 j peptones, 23 '06 ; meat bases, 8'94; fat, O'lS ; sodium chloride and phosphates, 9"68 per cent. Total nitrogen, 9'95 per cent. By precipitating the filtrate from the albumoses with bromine water, Allen found only 7'67 per cent, of peptones, and probably a large proportion of the nitrogen of the peptones in the manufac- turers' analysis ought to be assigned to the flesh bases. {Cf. pp. 201-202.) The Action of Pepsin. — Peptones are manufactured by the action of pepsin on finely divided flesh acidified with tartaric acid or hydrochloric acid. According to Denaeyer,* the tartaric acid peptones are in the form of a white hygroscopic powder with a marked after-taste. Owing to the length of time required for the action of the pepsin (at least twenty-four hours) and the large excess of tartaric acid necessary the proportion of albumoses and peptones does not exceed 35 per cent, and further decomposition products are formed. By the use of hydrochloric acid (2 per cent.) instead of tartaric acid a higher yield of albumoses and peptones can be produced, up to 70 per cent, being precipi table by alcohol, although Denaeyer states that in practice the quantity rarely exceeds 60 per cent. For the nature of the changes in proteids under the action of pepsin see pages 179-182. The Action of Trypsin. — Numerous pancreatised products are in the market. They are prepared by the action of alkaline tryp- sin on flesh, blood fibrin, milk, etc. As a rule they contain more or less of the amido-decomposition products of the proteids such as tyrosin, leucin, etc., which have a bitter taste (cf. pp. 182 and 203). The peptones of Sanders Ezn and of E. Merck are said to be pre- pared by this process. Papayotin Peptones. — Cibil's peptone in America and Ant- weiler's peptone in Germany are stated to be the products of the action of papayotin on flesh (ef. pp. 198 and 203). It is said that Antweiler's preparation is manufactured by removing the collagene from the flesh as completely as possible by boiling it with water, and then acting on the residual fibre with the juice of the plant. Physiological Value of Fluid Beef and Flesh Peptones. — An enormous amount of controversy has taken place on the subject of the nutritive value of these semi-digested products, and conflict- * La Composition des Peptones de Viande, pp. 6-8. PHYSIOLOGICAL VALUE OF 'PEPTONES.' 191 ing evidence as to the results of experiments with various prepara- tions is brought forward. Ahsorption of Proteids. — The view formerly accepted was that all proteids were converted in the intestine into peptones, and that the latter by reason of their more diffusible nature were readily absorbed into the blood. It is now known that the process of peptonisation is not necessary for absorption, and that, when it does occur, some further alteration of the albumoses and peptones formed must be brought about by the blood capillaries of the in- testine wall before they can pass into the blood. Absorption of Syntonin and Albuminates. — Many, if not most, of the albuminous substances can be directly absorbed as acid or alkali compounds, as was shown by the experiments of Voit and Bauer, who introduced syntonin from beef muscle and albuminate from egg albumin, into the small intestines of dogs, from which enzymes had been previously removed, and found that whilst only traces of albumoses and peptones could be detected at any given stage, the proteids were completely absorbed in one to four hours. Injection of Albumoses and Peptones. — Moreover, albumoses and peptones are never foxmd in the blood, and when introduced by way of a vein are promptly eliminated through the kidneys. If the quantity injected be large, symptoms of poisoning ensue simi- lar to those caused by toialbumoses. In most cases the coagulation of the blood is interfered with, although it is remarkable that protoalbumose and antipeptone do not have this effect (Kiihne). Food Value of Albumoses and Peptones. — Experiments have shown that certain albumoses and peptones are quite capable of replacing the daily loss of nitrogen arising from the decomposition of the cells, and establishing equilibrium, but in Neumeister's opinion* they have no more nutritive value than native albumin- ous substances for healthy persons, and he considers the point as more than doubtful in the case of invalids. C. Voit,t too, found in his experiments that antipeptones acted like gelatin in sparing albumin, though they could not replace it. {Cf p. 188.) A further question arises as to the effect of the continued use of albumose and peptone preparations as substitutes for native albu- minous substances. From the observations of Zxmtz, of Gerlach, and of Pfeiffer with various substances of this nature, unpleasant after-effects frequently result. In the present state of our knowledge, or rather want of know- ledge, as to the changes which peptones and albumoses imdergo before their absorption into the system, it seems somewhat pre- * Lehrbuch Phys. Chem., p. 306. t Viertelj. Chem, Nahr. Genussm., 1897, p. 165. 192 FLESH FOODS. mature to conclude from insufficient experimental data that the hydrolysed products of proteids, obtained by an artificial process outside the body, can universally replace natural albuminous sub- stances or their digestion products formed under imperfectly known conditions. The Analysis and Composition of Meat Extracts and Peptones. The determination of water, mineral matter, total nitrogen, soluble albumin, gelatin, and added meat fibre are now usually made as described in Stutzer's method (p. 193), with slight modi- fications, and it is only in the differentiation of other kinds of soluble nitrogen that essential differences are found in the methods used by various chemists. The author has made use of the following method in recent analyses of these preparations. Syntonin is determined in the filtrate from the coagulated albumin by rendering the liquid slightly acid with acetic acid, adding potassium ferrocyanide, and heating. If any precipitate formed on the addition of the reagent does not redissolve, the liquid is exactly neutralised, with litmus as indicator, the precipi- tate filtered off, and its nitrogen determined by Kjeldahl's methodj and multiplied by the factor 6*25. Albumoses. — The filtrate from the syntonin, or, in its absence, from the coagulable albumin, is saturated with zinc sulphate as described on page 164. The precipitate is washed with a saturated solution of zinc sulphate, and the nitrogen it contains estimated in the usual manner and multiplied by the usual factor. Peptones. — To an aliquot portion of the filtrate from the albu- moses is added an excess of bromine water as recommended by Allen, the precipitate being collected and its nitrogen estimated as described on page 168. Ammoniacal Nitrogen. — A second aliquot part of the zinc sul- phate filtrate is distilled with barium carbonate. Meat Bases and Amido- Compounds. — The total nitrogen in a third aliquot portion of the filtrate from the zinc sulphate pre- cipitation is determined, and the difference between the result and the peptone and ammoniacal nitrogen previously determined may be taken as the nitrogen of the meat bases and other nitrogenous compounds. Stutzer's factor (3'12) is most commonly used for calculating the nitrogen into meat bases, etc., but is only an approximation. Hehner prefers to use the factor 6 '25 for all the nitrogenous con- stituents, since although this is much too high for the meat bases, ANALYSIS OF MEAT EXTRACTS. 193 it makes the non-nitrogenous extractives (determined by difference) considerably lower, and the two errors balancing one another to some extent, he considers that the results thus calculated represent more nearly the true composition of the preparation. Stutzer's* Method.— i. Estimation of Water, Ash, Sodium Chloride, and Total Nitrogen. — From 5 to 7 grammes of a dry pre- paration, or from 20 to 25 grammes of fluid extract, are weighed into a thin tinfoil basin, dissolved in a little hot water, and ignited sand (freed from dust by means of a sieve) added in suflScient quan- tity to absorb the liquid. The basin and its contents are then dried until the weight is constant, the loss giving the water. The basin and the residue are subsequently used in the estimation of gelatin (see iv.). Similar quantities of the preparations are taken for the deter- mination of the ash, sodium chloride, and total nitrogen, all of which are carried out in the ordinary manner. ii. Nitrogen in the Form of Unaltered Proteids, Coagulable Albu- min, and Flesh Powder. — In order to detect the presence of meat fibre, the extract is treated with cold water and examined micro- scopically. If fibre be found the following method is adopted : — From 5 to 25 grammes of the preparation according to its state of dryness are repeatedly extracted with cold water, the insoluble matter collected on a filter, and the nitrogen it contains deter- mined. This gives the nitrogen of the flesh powder with slight quantities of other unaltered proteids. The filtrate is acidified with acetic acid, boiled, and filtered. The nitrogen of the insoluble portion is that present in the form of coagulable albumin. When meat-fibre is absent, a weighed portion of the extract is treated with water and acetic acid, and the nitrogen of the insoluble portion (coagulable albumin) determined as before. The filtrate may also be made up to a definite volume and the nitrogen determined in an aliquot portion. The difference between the result and that of the total nitrogen gives the amount present in the form of albumin. iii. Nitrogen in the Form of Ammonium Salts. — From 5 to 25 grammes of the preparations are dissolved in water, barium carbon- ate added, and the ammoniacal nitrogen distilled into standard acid. iv. Gelatin Nitrogen. — The residue of sand and extract left in the determination of the water in i. is ground in a mortar, the tinfoil cut into small strips, and the whole placed in a beaker where it is extracted with 100 c.c. of absolute alcohol, the supernatant liquid being removed each time by filtration through an asbestos filter. The residue is now treated with a mixture of alcohol and ice- * Zeit. anal. Chem., 1896, pp. 372 and 568. N 194 FLESH FOODS. ■water, prepared by mixing in a large flask 100 grammes of alcohol with about 300 grammes of ice and adding sufficient water to bring the total weight up to one kilogramme. This flask and four beakers (b, c, d, and e) are placed in a bath filled with broken ice. The beaker a, containing the sand, peptone, etc., is also placed in the ice-bath, and 100 c.c. of the alcoholic ice- water poured into it, care being taken to keep the temperature of the mixture below -f- 5° C. After the whole has been stirred with a glass rod for about two minutes, the supernatant liquid is poured into beaker b, a piece of ice being added at the same time. The extraction in beaker a is then repeated with a fresh portion of alcoholic ice- water, the liquid being decanted into beaker c ; and this process is continued until the liquid above the sand is completely colourless. In order to filter the extracts three asbestos filters are used. These consist of funnels about 7 cm. in diameter at the top, in each of which is placed a perforated porcelain disc covered with long-fibred asbestos. The first filter receives the liquid in beaker a and the insoluble residue excepting the sand. The contents of beaker b are poured upon the second filter, while the third filter is used for e, d, and e. After being well washed with the alcoholic ice-water, the whole of the asbestos filters and the sand in beaker a are repeatedly boiled with water, the extracts filtered, the imited filtrates concentrated by evaporation, and the residue used for the determination of the gelatin nitrogen. V. Nitrogen in the Form of Flesh Bases and Decomposition Pro- ducts Soluble in Alcohol. — Five grammes of the dry preparations are warmed in a beaker with 25 c.c. of water. In the case of extracts 10 grammes are taken with 10 c.c. of water, and with fluid preparations from 20 to 25 c.c. are taken and no water used. Thin peptone solutions should be concentrated to about one-haK their volume on the water-bath. To the solutions 250 c.c. of absolute alcohol are gradually added with continual stirring. After standing from ten to twelve hours the liquid is filtered, and the residue repeatedly washed with alcohol. Leucine, tyrosine, and other decomposition products, together with part of the flesh bases, will be in solution. The alcohol is com- pletely removed by distillation, the residue dissolved in water, and the solution filtered from the insoluble matter. The nitrogen of the insoluble residue is determined and added to the albumose nitrogen subsequently determined. The filtrate is diluted to 500 c.c. and 100 c.c. taken for the estimation of the total nitrogen present, and a similar amount for the ammoniacal nitrogen. The difference between the two results gives the nitrogen present in the form of flesh bases and decom- position products. stutzek's method of analysis. 195 vi. Treatment of the Residue Insoluble in Alcohol. — The filter con- taining the insoluble residue from v. is washed with water into a beaker, the alcohol evaporated on the water-bath and the liquid filtered. A small quantity of the albumoses usually becomes insoluble through the action of the alcohol, and the nitrogen in this must be determined and added to the albumose nitrogen subsequently found. The filtrate is made up to 500 c.c, of which 50 c.c. are taken for the total nitrogen, 50 c.c. for the albumose, gelatin, and peptone, and 100 c.c. for the peptone alone. The remainder of the liquid is concentrated by evaporation and tested for peptones by the biuret reaction applied to the filtrate obtained after precipitating the albumose and gelatin by saturating the liquid with ammonium sulphate. vii. Pancreas Peptone. — ^The solution obtained in vi. contains, in addition to gelatin and albumose, the entire pancreas peptone. One hundred c.c. of the aqueous solution are evaporated to about 8 or 10 CO., the gelatin and albumose precipitated by the addition of at least 100 c.c. of a cold saturated solution of ammonium sulphate, the precipitate washed with the same solution and dis- solved in boiling water. The solution is then evaporated to dry- ness with barium carbonate to expel all the ammonia, the barium sulphate and carbonate removed, and the nitrogen found in the filtrate taken as that of pancreas peptone. viii. Albumose Peptone. — A small quantity of this will have been found in v. and vi., but the bulk is present in the solution in vi. Fifty c.c. of this are mixed with an equal volume of dilute sul- phuric acid (1 : 3), and phosphotungstic acid added in the cold so long as a precipitate forms. The precipitate is washed with dilute sulphuric acid and its nitrogen determined. This consists of nitrogen in the form of albumoses, pancreas peptones, and gelatin, of which the last two have already been determined. The differ- ence gives the nitrogen in the form of albumoses, and to this must be added the small amounts found in v. and vi. ix. Nitrogen in the Form of Flesh Bases insoluble in Alcohol. — This is obtained by taking the difference between the total nitrogen of vi. and that found in viii,, after precipitation with phospho- tungstic acid. The analyses on p. 196 are given by Stutzer* to illustrate his method. The chief objection brought against this method is the inac- curacy of the phosphotungstic acid precipitation (cf. page 167), since undoubtedly in many cases it causes a considerable propor- tion of meat bases to be classed among the peptones. Moreover, it * Zeit. angew. Chem., 1895, p. 157. 196 FLESH FOODS. is doubtful from the experiments of Kbnig and Bomer and of Allen whether peptones (or, in other words, hydrolysed proteids precipi- tated by bromine but not by saturation with ammonium or zinc sulphate) are ever present in more than traces in meat extracts properly so called. Liebig's Extract. Kem- merich's Extract. Bovril Fluid Beef. Bovril Fluid Beel, Seasoned. Bovril for Invalids. Bovril Beef Jelly. Bovril Lozenges. Water Sodium cliloride, Other salts, Organic matter, 1772 3-11 19-63 59-64 16-54 4-15 17-96 61-35 29-14 14-12 3-38 53-36 44-42 10-72 7-60 37-26 28-13 4-57 11-50 55-80 89-15 0-26 1-04 9-55 9-47 1-63 5-71 83-19 Nitrogen was present as — a. Albumose peptone, h. Pancreas peptone, c. Flesh hases, etc. sol- uble in alcohol, d. Do. insoluble in alcohol, e.. Albumin, . f. Muscular fibre, . g. Gelatin, h. Ammonium salts. Total nitrogen, 0-56 2-72 1-24 2-38 1-23 3-36 0-34 1-39 1-26 3-36 0-16 0-48 2-06 6-06 3-28 |4-05 1-34 3-62 3-69 1-25 4-59 1-06 1-16 1-73 1-16 0-89 4-62 1-78 0-82 0-64 0-21 0-20 8-12 0-55 1-16 5-39 0-12 4-94 0-09 2-22 0-31 0-73 2-05 0-08 0-90 2-60 0-24 0-70 0-41 1-71 0-42 0-57 0-12 0-04 0-48 0-09 0-05 0-46 1-04 0-09 0-31 0-98 0-09 0-27 0-94 0-15 0-38 0-29 0-12 0-99 0-70 0-42 0-52 0-51 0-40 0-36 0-53 0-41 1-12 9-31 9-16 8-25 6-12 8-69 1-46 11-94 Although Schjerning asserts that he has found true peptones in considerable quantity in Liebig's Extract by his method of precipi- tation with various metallic salts, he does not prove the identity of the substances which he has separated with those which give the biuret reaction and are precipitated by bromine after the re- moval of albumoses from the solution (c/. pp. 159 and 204). The recent analyses by Hehner given on p. 197 show the com- position of a number of well-known preparations. They were made by a method essentially the same as that of Stutzer, Each COMPOSITION OF EXTRACTS OF MEAT. 197 Total Kitrogen. t* T-H O OJ T-H CM CD O 00 Oi t^ T^ ia la oo p >fs co -^ p « co -^ co p CO CD XO lOiH (NCOCOO O "* COCOr-HO CO Sodium Chloride. i-( "^ f-i 'TjiCO mcOOii— 1 CO t-^ (NCOCOCO ?■ ^ "P T* 9^'?^'?° 9^ S° i) >ii O OOC^ 01.^.^0 O « "CtOOOO ■*!< 1-1 i-i fH Albumoses. iH W5 OS C-150 000500 Ca OO OO^DSDiO ^ p 1^ r-( «5p pp,r-lp r-t 03 C0»£5p«p t;^ (M --1 -^ COt-H (MrHl-(0 O OO (NiOrHCO »-H Meat Fibre and Coagulable Albumin. T^ .ooco. ..oco .eocoooc-ioa (N • i^ 1^ • • - -ill o * ya ^- ITS ITS o • Albumin. 1-00 0-25 5-62 16-44 4-43 2-19 6-12 Gelatin. oo .-H (O O Oi urSCMt^Ki 00 I-H V) ^ ZO ITS Oi i^ CO u3 'P^ ^•r'?^'?* T* 'y' 9^^^*??^ ^ lO CO -^ lOO Oi-HrHC> Ift CO ?-(-*(NO i-H Fat (Petroleum) Spirit Extract. -* i-H OO oao ooointN eo W (Mt^i-l.-i o CO W M r-t I-H I-H I-H i-l rH rt 198 FLESH FOODS. of the nitrogenous constituents was calculated from the nitrogen as determined by Kjeldahl's method, the factor 6-25 being used in every instance : — Kcinig and Bomer obtained the results given in the subjoined table in the course of their critical examination of Stutzer's and Kemmerich's methods (pp. 193 and 201). They assigned the nitrogen found as follows :^ Total Nitrogen Found, Liebig'a Extract. Kemmerich's Extract. Kemmerich's Peptone. Cibirt Extract. 9-28 9-14 10-08 2-77 M ^°.25 to^ 0-16 1 3-69; 0-60^ 0-20 3-29J 0-45^ 0-« V4-48 0-18 3-40J 0-30> 0-27 ,2-67 0-06 i-os; Nitrogen from Gelatin, . ,, , ,, Albumoses, „ ,, Peptones, Total Soluble Proteids, . Insoluble Albumin (Meat Fibre), . 019) 0-80^3-93 24-66 0-25) 0-96^3-78 2-68 i 23-62 0-12) 76^3-57 2-70 1 22-40 6-81 0-06) 0-45^1-83 l-33> 11-43 7-43 * ForschunqsBer., 1894, p. 423 ; cf. page 199. t Journ. Pharm. Chim., 1897, v. p. 515. COMPOSITION OF COMMERCIAL 'PEPTONES.' 203 ■y QO (N CXD u Insoluble. : : 00 o n '■Ji Soluble. o 00 : OO «3 o 00 (M Chlorine or . 6"? ■* CO CO CO CO CO NaCl. ■^ la OS O tN. i '•~'~^ Phosphoric to CO o in OS C3S CO Acid. l-t CO CO o » QO r- CO (N Salts. OO CO Oi co t-. CO CO ■^ CD CO t^* CO f-H CM I-H r-i Fat = Ether CO CO CO o CO O Extract. o o o O o i-l Other ir^ 00 o •rH o ^-. CO 1 Nitrogenous Compounds. o o CO CO I-H O OS o \a t- CJS O Peptones OS T(l ■* t» T— 1 o NX6-25. t^ (M CO -* o cq CO (N CO CO CO CO CO cq -<*< CD CD Propeptones. O I— ( o CO in ■in ■^ ^^ Insoluble a:) CO i:^ CO (M o OO Proteids cS CO (N -* I-H CO NX6-25. .i3 o o o CO l-H o l-H CD r-l to lO OO o M lO ■^ QO t^ iO Tot al Nitrogen. «31 CO I-l Ol OO (M OS CO (N 00 t-- ^ Org anic Matter. OS OO to 00 in -"SP OO lO N o r^ Water. ■^ OS A-^ l>- CO tH CO (M (N ^^ ^-s , a> • o '-H k i? o iq fe3 g a. -2 1 s o is- CO CO i >-, s (- p< ■¥, aai p-t P4 ^ rt CK fsa tn £ g^« fO |2l la IS ■sl P4 ^ a -^ w o 6 < M t^ 204 FLESH FOODS. The criticisms of Konig and Bomer on Kemmerich's work are in the main also applicable to Bruylant's method. At best the separation is not sharp, and variations in the strength of alcohol ■would alter the proportion of the constituents in each group. In some cases in which the decomposition of the albumin molecule had been carried slightly further, products of lower molecular weight and of greater solubility would be grouped with the peptones, although by saturating their solution with zinc sulphate or am- monium sulphate they would be found among the albumoses. Although by alcoholic precipitation concordant results can be readily obtained, which will indicate more or less accurately the degree of hydrolysis which the original proteid molecule has undergone, the method is much less convenient and exact than separations effected by means of zinc sulphate and bromine. Older Analyses of Flesh Peptones. — Konig * gives the foregoing analyses (see p. 203) of preparations of this class. As the pro- peptones (albumoses) were estimated by precipitation with ferric acetate, and the peptones by precipitation with phosphotungstic acid, the nitrogenous constituents returned as peptones probably contained a large proportion of albumoses as well as of meat bases. By precipitating the albumoses by saturation with ammonium sulphate Kcinig obtained the following amount of albumoses and peptones from Cibil's and Antweiler's peptones. Albumoses. Peptones. Cibil's a, „ * Antweiler's .... 13'71 6-51 47-74 28-29 9-62 27-10 Schjeming's Method. — The precipitation of the proteid sub- stances in meat extracts, etc., in the form of distinct metallic com- pounds, is carried out as described on page 171. In a recent communication to the author, Schjerning states that he includes the peptones under the term of ' protein substances,' and that he defines them as ' proteids not precipitated from a neutral or acetic acid solution on moderately warming the liquid after saturation with a readily soluble sulphate.' For the saturation he prefers magnesium sulphate, finding that it precipitates the same quantity of proteid nitrogen as zinc or ammonium sulphates. Schjerning's peptone therefore agrees with Kiihne's definition of a true peptone (but cf. page 196). * Nahr. u. Oenussm., II. p. 186. SCHJERNING's ANALYSES OF MEAT EXTRACTS, ETC. 205 ' Denuclein,' he asserts, is not a proto-albumose, since all albu- moses are precipitated from an acetic acid solution by saturation at 30° to 36° C. with a readily soluble sulphate, whilst denuclein is not thus precipitated. It is rather, as its name denotes, a lower nuclein compound, and possibly a nucleic acid substance. In support of Schjerning's position it may be pointed out that in the table of Konig and Bbmer's results (page 198), about 9 per cent, of the total nitrogen in Liebig's Extract is not classi- fied under the head of albumin, albumoses, peptones, flesh bases, or ammonia, but belongs to other nitrogenous compounds. Some of Schjerning's results are shown in the subjoined tables : — I. Precipitation with Liebig's Flesh Peptone. Witte's Peptone. Liebig's Extract. 1896. Liebig's* Extract. 1899. a. SnClj PbAC2 . h. HgCl, . c. FeAcj d. UAoj e. MgSoj 13-0 t 24-8 57-2 55-3 48-1 13-5 t 24-5 56-6 £5-9 48-1 3-0 t 34 59-4 55-9 47-2 3-0 34-0 55-1 47-2 10-7 192 26"3 36-7 15'1 5-5 14-8 24-7 32-3 15-1 Allowable Error Per Cent. 0-5 0-8 0-8 0-5 II. Liebig's Elesh Peptone. "Witte's Peptone. Liebig's Extract. 1896. Liebig's Extract. 1899. Albumin I. , Albumin II., Denuclein, . Albumoses, . Peptones, . 13 3-4 8-4 32-4 -1-9 13 '5 2-5 8-5 32-1 -1-6 3-0 18-8 12-2 25-4 -3'5 30 31-0 I-21-1 10-7 -1-7 10-2 11-4/17S 5-5 -0-3 9-6 7.g|17 5 It is remarkable that the combined amount of the nitrogen from the albumoses and 'peptones' should be identical in the two samples. * Unpublished. t The precipitation could not be made. 206 FLESH FOODS. The residual nitrogen representing the flesh bases, amido-com- pounds, ammonium salts, etc., was calculated to be 63"3 per cent, in 1896 and 67'7 per cent, in 1899. It is suggestive that Kbnig and Bomer assigned about 10 per cent, more nitrogen to the flesh- bases and found no peptone nitrogen, whilst Schjerning obtained about 10 per cent, of the latter (p. 198). Although in certain cases Schjeming's process may eventually be found a satisfactory method of fractionating the proteid nitrogen in different organic substances, it suffers at present from* the drawback of being new and of yielding results which are difficult to compare with those of older methods. Probably the metallic compounds obtained by it are of a more definite character than those which, like the compounds yielded by saturating the solution with salts, are only separated from one another by a difference in solubility. If this be the case, and if the physiological characteristics of the various proteids precipitated in combination with the metals be determined, a distinct advance will have been made in estimating the comparative value of different meat extracts and similar preparations. CHAPTER X. THE COOKING OF FLESH. Advantages of Cooking. — The process of cooking has three main advantages: — (1) It renders the flesh more appetising by the development of certain odours and flavours under the action of the heat ; (2) it destroys animal parasites, and to a certain extent bacteria and bacterial products ; and (3) the flesh is eaten at a temperature more favourable to the action of the gastric juice. On the other hand, the digestibility of cooked meat is consider- ably less than that of raw meat, as was shown by Chittenden and Cummins,* who found that if the digestibility of cooked beef in artificial pepsin solution be taken as 100, that of raw beef may be represented by 142 '38. The longer the cooking has been continued, the greater is the decrease in digestibility. The national economy of invariably eating flesh in a cooked condition is shown by the fact that Berlin employs over 200 trichinae inspectors, and Prussia more than 24,000, as a safe- guard against one of the dangers of raw flesh, t whereas in other countries, such as Italy, France, and England, where pork is, as a rule, only eaten in the cooked state, no special inspectors are em- ployed, and yet trichinosis is of comparatively rare occurrence. In Germany the public is now warned against eating raw meat, even after it has been inspected and passed. The Loss during Cooking. — This depends to a large extent on the method of cooking. According to Letheby,|: the average percentage loss in weight on boiling is 23; in baking, 31 ; and in roasting, 34. If the meat is placed in cold water which is gradually heated to the boiling-point, the loss is considerably higher, owing to the large proportion of soluble proteids, nitro- genous extractives, and mineral matter, which dissolves before the temperature (50° to 70° C.) is reached, at which the albumin begins to coagulate and to form a protective crust on the surface. Under these circumstances the loss may amount to from 30 to 40 per * Journ. Amer. Chem. Soc., vi. p. 318 ; cf. page 86. + Der FleisMeschau, p. 647. + On Food, p. 166. 208 FLESH FOODS. cent. (Strohmer). Part of the loss during boiling is due to some of the collagene being converted into gelatine and dissolving in the water. In roasting and baking the constituents of the flesh are retained much more completely than in boiling, and although the loss is apparently greater, it is almost entirely due to water. The figures given by Strohmer* as representative of the average loss in different kinds of flesh on roasting are considerably lower than those of Letheby — viz.. Beef, 19 per cent.; veal, 22 per cent.; mutton and poultry, 24 per cent. The Composition of Cooked Meat. — Roasting. — When meat is roasted there is a considerable loss in weight, amounting from 25 to 35 per cent, calculated on the original substance. This is mainly due to the evaporation of water and to loss of the substance of the meat in the form of dripping and gravy. By maintaining a high temperature during the initial stages of the process, the juice which first escapes from the meat becomes coagulated on the surface and furnishes a thin glaze, which pre- vents any further considerable loss of meat juice. Some idea of the difference in composition of raw and roasted meat may be obtained from the following analyses. As they represent cuts from different joints, they are not, however, strictly comparable : — Water. Nitro- genous matters. Fat. Ash. Beef, raw, ,, roasted, .... MuttOD, raw (Kbnis;), . ,, roasted (Mitchell), 71-68 50-82 75-99 45-21 20-52 25-05 17-11 31-84 6-72 21-65 5-77 21-37 1-21 1-45 1-33 1-58 The characteristic aromas of roast meat are due to the partial carbonisation of the meat fibre with the formation of odorous compounds. Boiling. — The change which meat undergoes during boiling difi^ers very much from that which takes place in roasting. The loss in water is much less, but the action of the boiling water on the collagene of the connective tissue causes a large amount of gelatin to be dissolved. The meat also loses much of its extractives and mineral matter, which will be found in the broth. This loss can be obviated to some extent by first placing the meat in boiling * Die Ernahrung des Menschen, p. 123. CHEMICAL COMPOSITION OF COOKED MEAT. 209 water, so as to coagulate the myosin of the muscular tissue, and thus prevent the loss of much of these constituents during the subsequent gentle boiling or simmering. When gravy or soup are required the opposite process is followed, the meat being placed in water of a low temperature, which is gradually heated, though not to the boiling-point. According to Pereira,* the average loss in weight in the joints of beef and mutton boiled for the inmates of the Wapping ware- house was 17 '5 per cent., but in Letheby's opinion this was con- siderably lower than the general average. 0. W. Andrews states that the total loss on cooking should not exceed one-fifth to one-fourth for boiled meat and about one-third for roast meat. Grilling and Frying. — Grilled meat resembles roast meat in many respects, but owing to the more thorough and direct action of the heat, there is a greater loss of water and of dripping, and a more complete carbonisation of the exterior meat fibre. In frying, which may be regarded as boiling in fat, the presence of the latter modifies the direct action of the fire. A. H. Church f gives the following analyses of raw and of cooked mutton chops : — Fresh mutton chop, minus bone — -Water, 44'] ; albumin, 1-7; fibrin (true muscle), 5 '9; ossein-like substances, \'2; fat, 42 '0 ; organic extractives, 1"8; mineral matter, I'O; and other substances, 2 '3 per cent. COMPOSITION OF TWO COOKED MUTTON CHOPS. Water. Nitro- genous Matters. Fat. Mineral Matter. Other Substances. I. Chop, including gravy and drip- ping, . II. Chop, without gravy and drip- ping, . 54-0 51-6 27-6 36'6 15-4 9-4 3'0 1-2 1-2 "Meat is tender if properly cooked before the rigor mortis has set in, but must be kept for some days after that rigidity of the muscles has set in," if the same degree of tenderness be required. | * Letheby, On Food. X Church, loc. dt., p. 163. t Food : Some Account of its Sources, p. 166. 210 FLESH FOODS. The Composition of Cooked Fish. — In a recent communication to the Chemical Society* Miss K. Williams gave the following results (among others) of her analyses of different kinds of boiled fish as they would be served at table. The salt cod and herrings were soaked in cold water before cooking, and the sardines well washed in boiling and cold water to remove as much surface oil as possible. When cold the inedible portions (bones, head, skin, etc.) were removed, weighed, crushed in a mortar, boiled in dis- tilled water, the liquid siphoned off and evaporated on a water- bath. The residue was dried until constant in weight and taken as gelatin. Name of Fish. Date. Portion Analysed. As served at Table. Waste — Nutri- ents. Bones, etc. Gelatin. Water. Herrings, Feb. Whole 11-74 0-63 52-99 34-54 Salt herrings, Jan. Flesh ,.. 46-03 53-97 Sardines, March Whole 4-91 42-17 52-92 Sprats, . Nov. 9) 17-90 0'-90 61-50 19-70 Salmon, July Section 5-99 0-53 61-06 32-02 Eels, . Oct. Heads re- moved 11-66 1-09 53-29 33-96 Mackerel, April Whole 10-51 0-25 65-21 24-03 Cod, . Jan. Section 15-99 0-43 63-78 19-79 Salt cod. Feb. 1) 6-13 0-33 67-68 25-86 Haddock, Jan. Whole 35-10 0-80 46-46 17-64 Turbot, . Feb. Anterior and head 31-20 0-69 53-09 15-12 Plaice, . Dec. Flesh 79-86 20-14 Soles, March Whole 22-b2 0-74 61-18 16-06 Oysters, )j Shell contents 77-71 22-29 A further analysis of the same specimens of fish gave the additional results given on page 211. The amount of reducing substances was obtained by removing the fat with benzene, and digesting the residue with 100 c.c. of water and 10 c.c. of hydrochloric acid (sp. gr. 1-125) on the boiling water-bath under a reflux condenser for three hours. The liquid was then filtered, basic lead acetate added, and a current of sulphur dioxide passed through the filtrate. The solution was again filtered, concentrated, and washed alumina added until it ' Journ. Chem. Soc, 1897, 652. CHEMICAL COMPOSITION OF COOKED FISH. 211 no longer dissolved. After filtration the liquid was evaporated to dryness at 100° C, the residue treated with boiling alcohol, the liqu.id filtered, and the alcohol removed by evaporation. The residue was dissolved in water, the liquid boiled with animal charcoal and a few drops milk of lime, filtered, and titrated with Fehling's solution. "With reference to the results thus obtained, H. A. Allen points "Water in Flesh. Analysis of the Dried Substances. Name of Fish. Fat Proteids Reducing Sub- Phos- Nitrogen Ash. (ether extract). (NX6-25). stances as Glucose. phorus. pent oxide. Herrings, 60-54 5-56 25-25 6707 91 0-66 Salt her- rings, . 46-03 19-69 21-90 38-88 17-59 0-89 1-64 Sardines, 44-3.') 12-03 33-49 55-44 0-97 Sprats, . 75-77 6-42 27-37 57-94 9-88 1-17 Salmon, . 65-32 4-94 29-43 66-65 14-89 0-51 0-46 Eels, . 6108 2-11 44-68 42-88 8-91 0-42 Mackerel, 73-13 4-07 25-73 62-32 13-93 0-85 0-.33 Cod, . 76-32 3-31 1-15 91-55 6-67 0-62 0-63 Salt cod, 72-35 14-26 0-94 76-06 7-14 29 0-31 Haddock, 72-37 3-28 1-29 79-57 1315 0-53 0-43 Turbot, . 77-84 2-41 4-75 84-71 11-81 0-57 Plaice, . 76-86 4 06 9-84 75 16 11-56 0-71 2-78 Soles, . 79-20 3-47 1-71 86-71 11-87 0-52 Oysters, 77-71 12-16 7-77 65-42 18-32 0-49 out that the reducing substances were probably not present as such, but were products of the hydrolysis of gluco-proteids by the hydrochloric acid. He also calls attention to the fact that these analyses do not confirm the popular belief that the amount of phosphorus in fish is very much greater than that of meat. The Effect of Cooking on Animal Parasites. — The experiments of Perroncito (pages 248 and 261) and others have shown that the cysticerci and other larvse of the tapeworms perish below 50° C, trichinae below 69° C, and that no animal parasite found in flesh is capable of withstanding as high a temperature as 70° C. If, then, this temperature is reached in every part of the meat during the cooking, all risk from this source is obviated. The Temperatures at -which Bacteria Perish. — Bacteria are much more resistant to the action of heat, especially of dry heat, than are the animal parasites found in flesh. Generally speaking, 212 FLESH FOODS. the pathogenic bacteria perish at a lower temperature than the non-pathogenic bacteria. Sternberg * exposed pure cultiva- tions of various micro-organisms for ten minutes at diiierent temperatures and obtained the following thermal death points : — Bacillus of Swine Erysipelas, Bacillus pyooyaneus, . Bacillus prodigiosus, . Bacillus fluorescens, . Bacillus acidi laotici, • Staphylococcus pyogenes aureus, °C. 58 56 58 54 56 58 °C. Staphylococcus pyogenes albus, . . . .62 Staphylococcus pyogenes citreus, . . .62 Streptococcus pyogenes aureus, . . .54 The following results have been obtained by other observers at difterent times : — B. of Swine Erysipelas. — Killed in 5 minutes at 55° C. in pure cultivations, but not destroyed in meat by ordinary cooking (Petri). B. of Hog CJiolera. — 15 minutes at 70° C. One hour at 54° C. (Smith). B. of Rabbit Septicemia. — 15 minutes at 55° C. ; 10 minutes at 80° C. (Ostertag). Jj. anthracit:. — 10 minutes at 54° C, or 20 minutes at 50° C. (Chauveau). 10 to 15 minutes at 55' to 60° C. (Besson). The spores failed to grow after 4 minutes at 100° C. (Sternberg). Spores destroyed by moist heat at 90° to 95° C, but capable of withstanding a much higher dry temperature (Besson). B. of Quarter Evil. — Virulent after an hour at 80° C. Killed after 5 minutes at 100° C. The spores only weakened in a current of steam (Ostertag). n. of G7rrHr/er«.— Killed at 55° C. (LofBer) ; 55° to 60° C. (Besson). B. tulierniJosix. — Perishes at 85° in pure cultivations (Bang). Can withstand 65° C, but perishes at 75° C. (Yersin). In milk, 4 hours at 55° C. ; 1 hour at 60° C. ; 15 minutes at 65° C. ; 5 minutes at 80° C. ; 1 minute at 95° C. (Forster). In the dry state resists 100° C. for 3 hours, and 70° C. for 7 hours (Welch). B. tetaivi. — Killed after 6 hours at 80° C. ; 2 hours at 90° C. ; and 8 minutes at 100° C. (Besson). The spores are extremely resistant to heat. Streptococcus pyogenes aureus. — One hour at 58° C, and a few moments at 100° C. (Besson). * Bacteriology, p. Ii7. INFLUENCE OF COOKING UPON BACTERIA. 213 Siaphijlocoecus pyogenes aureus. It, , ,, „, , icco/-, •^ ^-^ ^ ,, I Dead after 24 hours at 55 C, 'I " cUnus for 15 minutes at 80° C.(Besson). Bacillus coli communis. — 5 minutes at 66° C. (Besson). Bacillus typhosus. — From 10 to 20 minutes at 66° C. in pure cultivations (Besson). Action of Heat on Bacterial Toxines. — The excretory products of pathogenic bacteria consist as a rule of several active principles. They sometimes contain ptomaines apparently identical with those formed by purely putrefactive bacteria, sometimes definite bases only known to be formed by specific bacteria, together with various broken-down products of albuminous substances (toxal- bumoses, peptones, etc.). In some cases definite toxic products have been isolated from pure cultivations {cf. page 220), but as a rule the experiments as to the influence of heat have been made with the bouillon filtered free from bacteria and containing mixed toxic and harmless products. The following are some of the results which have been obtained : — Toxic Prorlucts of Staphylococcus pyogenes aureus. — The activity of the whole toxine is weakened at 58° C. There are two active principles in the cultivations, one precipitated by alcohol and destroyed at 104° C, the other not precipitated by alcohol and unweakened at 104° C. (Besson). Toxines of Tuberculosis and Glanders. — One or more of the active toxic principles in the products of B. tuberculosis and B. mallei are not destroyed at 100° C, as is shown by the method of preparing crude tuberculin and crude mallein. Toxine of Rinderpest. — Destroyed after 10 minutes at 55° C. (Semmer and Eaupach). Toxine of Sheep pox. — 10 minutes at 55° C. (Semmer and Eaupach). Virus of Rabies. — 10 minutes at 60° C. (Sternberg). Toxine of Anthrax. — Weakened but not destroyed at 100° C. Toxine of Tetanus. — Altered by heating at 65° C. for 5 minutes, and toxicity completely destroyed at 80° C. (Kitasato). The products of several of the bacteria of septicsemia have been shown to be toxic after boiling, and the same remark applies to many of the putrefactive poisons. Hence cooking, even if a temperature of 100° C. were reached in every part of the meat, cannot be regarded as a universal safeguard against bacterial poisons. Lehmann regards flesh infected with the following diseases as dangerous only in the raw or unperfectly cooked condition : — Cysticerci, trichinse, tuberculosis, glanders, actinomycosis and foot- 214 FLESH FOODS. and-mouth. disease. He considers flesh infected with splenic fever, malignant cedema, septicaemia, and chicken cholera as dangerous whether raw or cooked. The Temperatures reached in the Ordinary Process of Cooking. — Some of the experiments which have been made with the object of determining this point are given on page 262, where it is shown that cooking, if thoroughly carried out, destroys trichinae. In farther illustration of the fact that heat penetrates but slowly into the interior of flesh, the experiments of other observers* may be described. Eupprecht found that in the ordinary boiling of meat for | hour, as in Saxony, the interior temperature was at most 75° C. at the end of the time, and that, too, only when the meat was in thin strips. In blood sausage the temperature reached in the same time was 66° C. ; in tongue sausage 62-5° ; in ham 65° ; and in boiled pork 65°. The interior temperature of a rapidly-roasted sausage was only 28'7° C. Leuckart found that in grilled cutlets and sausages the highest temperature was 62-5° C., and that of roast pork 75° C. Wolffhiigel and Hueppe state that the temperature in the middle of large pieces of meat never reaches 100° C, and in their experiments this temperature was only once attained in the exterior parts. From these experiments it follows that many of the bacteria, if present in the interior of flesh, would probably survive the ordinary processes of cooking. In any case their spores would almost certainly retain their vitality. Fortunately the occurrence of the spores of such bacteria as those of anthrax or tetanus in meat is very exceptional. Changes in the Juices of Meat on Coolcing. — According to Strohmer an approximate idea of the highest temperature reached within the interior of the flesh may be formed from the appear- ance of the juice pressed from the cooked meat. He states that if this is a turbid liquid the temperature did not exceed 56° C. If it is clear red the temperature was probably between 50° and 60° C, but not exceeding 65° C. Between 70* and 72° C. the colour of the juice changes to brownish red, and between 75° and 80° C. to yellow. The Public Sterilisation of Infected Flesh in Germany. — Flesh containing only a few cystioerci, or infected with certain diseases, such as swine plague, swine erysipelas, etc., is allowed to be sold in Germany after having been thoroughly disinfected by cooking, under police supervision. For the sale of such meat, and of flesh which has been passed as of inferior quality, though not * Ostertag, Handbuch cUr FleischtescJmu, p. 548. PUBLIC STERILIZATION OF INFECTED FLESH. 215 dangerous to health, institutions, known as Freibimhe, have been established in connection with the local meat inspection in many of the towns, especially in the South of Germany. Such meat stamped by the Freibanh is sold at a very cheap rate, and is largely used by the poorer classes. The cooking is so arranged that the meat is thoroughly heated throughout. The flesh is divided into thin strips, which are boiled for two or three hours, or until the interior becomes grey. In this process, as ordinarily carried out, there is a considerable loss in nutritive value, and in order to obviate this, sterilisation by means of steam under pressure has been introduced in many places. In Kohrbeck's steam steriliser, constructed on this principle, every part of the meat is brought to a temperature of at least 100° C, while the meat juices and the flavour are retained to a much greater extent than is otherwise possible. CHAPTER XL POISONOUS FLESH. Flesh may sometimes be rendered injurious by contamination witli some drug such as chloride of lime, phenol, etc., but, apart from such cases, it may have inherent toxic properties, which may be derived — (1) from some injurious substance eaten by the animal ; (2) from poisonous products secreted by the cells of the living animal ; (3) from pathogenic bacteria or bacterial pro- ducts in the living animal ; or (4) from post-mortem, alteration of the flesh by bacteria. Flesh rendered Poisonous by the Food of the Animal. — Numerous instances are on record showing that flesh which is ordinarily wholesome may become more or less injurious from the food which the animal has eaten shortly before being killed. According to Letheby,* the flesh of hares which have fed upon the Rhodo'hnJron Chrysanthemum has caused illness, and similarly in Pennsylvania and Philadelphia, pheasants which have eaten the buds of the laurel (Cahnia latifolia) are unwholesome. In fact, Letheby attributes many of the illnesses which have occurred after eating prairie birds imported into this country from America to the nature of the food eaten l>y the bird. Sometimes in Aus- tralia the flesh of sheep acquires poisonous properties from the animals having fed upon the lotus, wild melon, and wild cucum- ber, the general effects being pains in the limbs, prostration, and sickness. The animals themselves are occasionally, but not in- variably, poisoned by their food. Possibly some of the cases of shell-fish poisoning which happen from time to time are to be attributed to this cause. And it is interesting to note in this connection that the Maletta venenosa, a poisonous tropical fish, is said to be venomous only at the times when the sea is covered with a green monad on which it feeds (Letheby). In 1842 a whole family in Toulouse were poisoned by eating a dish of snails collected from a poisonous shrub, Coriaria myrtifolia. Guenther t states that the poisonous nature of the * On Foods, p. 221. t The Study of Fishes, p. 189. POISONOUS LEUCOMAINES IN FLESH. 217 flesh of most, if not all, of the poisonous fish of the tropics is derived from their food, which consists of medusse, corals, or decomposing substances. Poisons. — Of inorganic poisonous substances taken by the animal, phosphorus is the only one known to produce more than local effects. In phosphorus poisoning the general symptoms are extravasation of blood, alteration of the tissues, and fatty degeneration. The blood is altered in appearance, and the flesh becomes phosphor- escent in the dark.* Wally considers that, with the exception of phosphorus, " inorganic poisons are never absorbed in sufficient quantity to render the flesh of the animal nocuous.'' The difierent instances mentioned above of flesh made poisonous by the food of the animal show that certain organic poisons, apparently of an alkaloidal or glucosidal nature, can produce general symptoms, and this is probably the case with many other organic poisons. Flesh Poisonous from Products elaborated by the Cells of the Living Animal. — Formation of Leucomaines and Toxines. — In 1882 Gautier showed that just as toxic products (ptomaines and toxines) are secreted by certain bacteria, so by a sort of euzymic action in the living cells the proteids or other nitro- genous compounds are normally broken down into less complex bodies, being finally transformed into urea, amides, hydrocarbons, carbon dioxide, bases, etc. To the basic substances, which are closely allied to ptomaines in many of their reactions and properties, he gave the name of leucomaines,^ or physiological alkaloids. The process of their formation is primarily a direct hydration, and is regarded by Gautier as an anaerobic fermentation. Most of the leucomaines thus formed are harmless, or only slightly poisonous, but some are extremely toxic, such as neurine and choline. Under certain circumstances leucomaines, or other decomposition products of proteids, may be of such a nature, or produced in such quantity and insufficiently eliminated from the system, as to cause auto-infection. An interesting illustration of this is afforded by the experiments of Professor Mosso of Turin, J who found that the illness caused by over-fatigue is due to the absorption of certain substances into the blood, and that these substances when injected into healthy animals produce the same symptoms. The presence of leucomaines in excess, or of toxines derived from the proteids, is probably the cause of the illness sometimes produced by eating the flesh of over-hunted game or of over- driven cattle. Liebig, in his Letters on Chemistry, mentions a case in which the flesh of a roebuck, which had struggled violently * Andrews, HandbooTc of Public Health, p. 20. t AewKB/ia = white of e£;g. J Lmicet, 1887, p. 1295. 218 FLESH FOODS. after having been caught in a snare, gave rise to symptoms of poisoning. According to Gautier,* pigs have been fatally poisoned through being fed upon the flesh of a horse which had died during its struggles when being broken in, and, like Liebig, he has known of cases of human poisoning by the flesh of roebucks which had died in a state of terror or exhaustion. Gautier t has also confirmed Landi's statement that when muscle, the cells of which are still living, is taken from an animal and protected from the influence of putrefactive bacteria, the action of the cellular protoplasm continues, and by a sort of anaerobic decomposition causes an increase in the extractives and toxic bases of meat, especially of those belonging to kreatinic and neurinic groups. Simultaneously there is a diminution in the proteids, and the glycogen disappears, but the fat is not appreciably affected. Eoger I considers that the toxicity of the extract of normal muscle is to be attributed to toxines of a proteid nature rather than to basic bodies, which are only moderately poisonous. By removing the crystallisable substances by dialysis, he obtained a residue of an albuminous nature, which on injection into rabbits produced symptoms of exhaustion, somnolence, diarrhcea, and death without, or attended only by slight, convulsions. The fact that the extract after being heated to 100° C. did not cause these results was regarded as proof that the leucomaines are not the poisonous substances. Leucomaines which are also known as Ptomaiaes.^ — Among the basic substances which have been found both in the products of bacterial putrefaction and among the substances elaborated by living cells, probably by the decomposition of lecithins, the following may be mentioned : — Choline [CjHjjNOj], which occurs normally in the blood, mus- cular tissue, and glands of the ox and other animals. It resembles neurine in its toxic action, but is weaker. Neurine [CgHjjNOg], which usually accompanies choline in traces, and is found in the brain and nerves. It is very toxic, and is regarded by Gautier as the probable cause of the roe of certain fish becoming poisonous at the spawning season. Betaine [GjHjjNOg], which is normally present in many animals, notably the mussel. Trimethylamine [(CH3)jN], which occurs in blood. Keuridine [C^Hj^Nj], found in the yelk of egg and in fresh human brain. Cadaverine [C^Hj^Ng], isolated in traces from fresh pancreas. Gerontine [C^Hj^N^li found in the liver of an old dog. * Les Toxines, 1896, p. 438. t Hid., p. 466. t Gautier, loc, cit., p. 455. POISONOUS FISH. 219 PoisonoTis Fish. — The following table of fish, certain species of which are known to be poisonous, either invariably or at certain seasons of the year, or after eating certain food, is given by 0. W. Andrews * : — Acanthopterygii or Spiny-rayed fislies, including Sparidm (sea- breams) ; Squamipinnes (coral fishes) ; Sphyrxnidx (bar- racudas) ; Scombrids. (mackerel) ; Garanyidee. (horse-mac- kerel) ; Acronuridx (sturgeons), and Atherinidx. Pharyngognathi, including Labridx (wrasses). Physostomi, including Silwidx (cat-fish) ; Clupeidx (her- rings). Plectognathi, including Sclerodermi, e.g., Balistes and Ostra- cion ; Gymnodontes (Diodon, Triodon, and Tetrodon). Of the bream family (Sparidx) the Spanish bream {Pagelus erythrinus) is met with off the shores of New Caledonia and New Hebrides. Its poisonous properties are possibly due to the nature of its food. The Leihrinus mambo is another member of the same family, and is found in the same waters. Its flesh is said to be innocuous when young, but to be very poisonous when full grown. Among the coral-fish the Heniochus macroleptidotus is distin- guished for the brilliance of its colouring and its poisonous properties. It is found in the neighbourhood of coral-reefs and is carnivorous. The barracudas (Sphyrasna barracuda) are found in the West Indies, and are usually poisonous. They are large fish, often 8 feet long and 40 lbs. in weight. The Caranx fallax, which is a member of the horse-mackerel family, is said to be wholesome when young, but poisonous when full grown. It is met with in Australian waters. Different varieties of wrasse are known as parrot-fish from their brilliant colour, and appear to be poisonous from the nature of their food. The cat-fish (Siluridx) are usually found in fresh water, and only those varieties which enter the sea are regarded as poisoQous. Their skins are smooth and without scales. According to Guentherf the flesh of certain members of the herring family, such as Glupea thryssa and Clupea venenosa, ■ is always poisonous. Clupea thryssa (the yellow-billed sprat) is exceedingly poisonous, and has been known to cause death before being actually swallowed. Tetrodon and Diodon, known as 'globe-fishes,' are covered with spines, and have the power of distending their bodies with air into a globular form, and floating on the surface of the water * Haridhooh of PuUie Health, 1898, p. 51. t The Stvdy of Fishes. 220 FLESH FOODS. with the underside uppermost and spines protruding. Guenther states that some of the species are always poisonous. Balistes, or 'file-fishes,' are so called from the file-like edge of the dorsal fin. They feed on coral and molluscs, from which they probably derive their poisonous properties. The Ostracion, or 'trunk-fish,' is protected by a covering of bone-like plates. Like the preceding fish, it is found off the American coast and in Indian waters, and is universally regarded as poisonous. Many of the smaller varieties of these poisonous fish are eaten by larger fish, such as difi'erent species of dolphin, conger-eel, etc., and cause the flesh of these to be also poisonous for some time afterwards. In some fish a poisonous substance appears to be secreted only at certain times of the year, as, for instance, in the case of the pike and the turbot, whose roe produces violent diarrhoea when eaten during the breeding season.* According to Letheby the general symptoms caused by eating poisonous fish such as these, are either irritation of the stomach and intestines, with choleraic symptoms, or rapid prostration and convulsions. Flesh rendered Poisonous by Bacteria in the Living Animal. — In addition to certain definite diseases, such as tuberculosis, wliich may sometimes be communicated through the presence of the specific bacilli or their products in the flesh, there have been numerous obscure cases of poisoning, the symptoms of which resembled, to some extent, those of ptomaine poisoning, although there was no sign of putrefaction in the meat. In some of these cases it is not improbable that ptomaines may actually have been present, and have contributed to the result, since it has been proved that these bases may be formed in cultivations by bacteria other than those usually associated with putrefaction. Thus putrescine has been isolated from cultivations of the Bacillus coli communis, cadaverine from cultivations of Koch's comma bacillus and Tinkler and Prior's bacillus, and methyl-guanidine from the substances elaborated by the bacillus of mouse septicaemia. Bollinger t considers that septicaemia and pyaemia must be regarded as the causes of many cases of poisoning, and he con- siders them as of almost more importance than any other disease, owing to their frequent occurrence. During the four years pre- ceding 1880 he had under his notice eleven cases of wholesale poisoning, and 1600 cases of individual illness, which he con- sidered were undoubtedly the result of septioasmia or pysemia. In 1874, in Bregenz, fifty-one people were poisoned by the flesh * Guenther, loo. cit., p. 189. t Oatertag, Hcmdbuck der Flcischbcschau,- p. 469. FISH CHOLERA — MUSSEL POISONING. 221 of a cow which had been slaughtered on account of septic injuries received during calving. A similar case occurred in 1876 in Bavaria, in which twenty two persons were made ill with choleraic symptoms. The cooked flesh and cooked sausages made from it were also injurious. In another instance seven people were poisoned by beef from a young cow which had been infected with puerperal sepsis before being killed. After four days the flesh showed marked signs of decomposition. In Ostertag's * experience there were 1500 cases of illness of this nature, principally in Germany, during the twelve years preceding 1892. From these and similar cases, which might be cited ad infinitum, there can be but little doubt that a septic condition in the animal is a frequent cause of its flesh having poisonous properties. Fish Cholera. — This is a disease which is epidemic among sturgeon and other fish. Its cause was investigated by Sieber- Schoumow,t who found in the stomach and intestines of the fish a motile and anaerobic bacillus, B. piscicidus agilis, which, on inoculation, produced the disease in healthy fishes. From the sterilised cultivation a very toxic base was separated, which he regarded as contributing to the disorders produced by fish which are normally wholesome, but become poisonous when attacked by this and similar bacteria. Fischer and Eber isolated from the blood of a carp which had been killed by the impurity of the water a bacillus which was exceedingly toxic to warm- or cold-blooded animals, and which elaborated a poisonous toxine. This, unlike the ptomaine of fish cholera, was destroyed by boiling. Mussel Poisoning. — Severe illness is sometimes produced by eating mussels, the principal symptoms being vomiting, diarrhcea, difficulty in breathing, feeble pulse, prostration, a rash all over the body, dilation of the pupil of the eye, and sometimes swollen tongue and throat. In 1885 there was an epidemic of mussel poisoning in Wilhelmshaven, many of the cases proving fatal in the course of three or four hours. Some of the victims had not eaten more that five or six of the mussels. Kdnig states that poisonous mussels are usually of a brighter yellow colour, but those of darker colour have also been known to cause the same symptoms. The life conditions of the mollusc appear to have a considerable influence on its wholesomeness, for Virchow and Schmidtmann found that when poisonous mussels were left in pure sea-water they became harmless in the course of a month. Similarly * Handhuch der FleiscJiieschau, p. 475. t Arch. Sciences biol. de St. Petersburg, 1894, iii. p. 241. 112. FLESH FOODS. M. Wolff and Konig * found that mussels placed in the stagnant water of the harbour became poisonous in two or three weeks, while poisonous mussels placed in the neighbourhood of a sluice where the water was frequently changed became harmless again. The mussels collected in January and February were more poisonous than those gathered in November and December. From Wolffs * investigations the poison seems to be chiefly developed in the liver, while the foot, gills, mantle, and eggs are non-poisonous. Schmidtmann t considers that the poison is caused by a definite disease, probably bacterial and communicable. Mytilotoxine. — Brieger f isolated from poisonous mussels a ptomaine or leucomaine to which he gave the name of mytilotoxine. It was accompanied by large quantities of betaine, which was also found in non-poisonous mussels. The constitution of mytilotoxine is uncertain, but it may be regarded as a methyl derivative of betaine with the formula (ch3)3n/cKco6h. Possibly it is formed by a diseased condition of the animal from the betaine normally present or by the action of pathogenic bacteria derived from the water. The method adopted by Brieger for its isolation is described on page 315. It was not found among the products of the putrefac- tion of ordinary non-poisonous mussels. The free base is an unstable resinous body with a disagreeable odour. It is extremely toxic, and the least traces of its hydrochloride, when injected into animals, produce all the symptoms of mussel-poisoning. Free mytilotoxine rapidly loses its poisonous properties on heating, and on dry dis- tillation yields large quantities of trimethylamine. Flesh rendered Poisonous by the Action of Bacteria on the Dead Flesh. — It had long been known that an aqueous extract of decomposed animal matters had toxic properties, but it was not until 1855 that the Danish chemist Panum showed that the poison was of a chemical nature, and probably contained several active principles. His results were confirmed by Bergmann, Mtiller, and other chemists, especially in Germany, but the chemical nature of the toxine was not determined. In 1869 Sonnenschein and Ziilzer extracted from flesh which had been left to decompose for five or six weeks traces of a crystalline basic substance, which gave the * Konig, JVahr. Gcnussni., ii. p. 103. + Quoted by Gantier, Les Toxines, p. 135. J Virchow's ArcMv, 1889, cxv. p. 483. SUMMARY OF THE PRINCIPAL PTOMAINES. 223 reactions of alkaloids, and had physiological properties resembling those of atropine. In the following year Selmi found that sub- stances of an alkaloidal nature were normally present in the stomach of a dead animal before and after putrefaction ; in 1874 he definitely announced that basic substances resembling the vegetable alka- loids were formed during putrefaction, and gave them the name of 'ptomaines' (7rT(D/ia=dead body); and finally, in 1877, came to the conclusion that these substances were bacterial products. The first ptomaine isolated as a pure chemical substance was collidine, which was extracted by Nencki from a putrified infusion of gelatin. Since then a large number of well-defined ptomaines have been isolated by other workers in this field, among whom may be mentioned Gautier and Etard, Pouchet, Salkowski, and especially Brieger. Summary of the Principal Ptomaines. — The principal bases which have been separated from decomposing flesh are given in the subjoined table, in which Gautier's scheme of classification has been adopted. Monamines of the Fatty Acid Series. Trimethylamine. (CH3)3N. Herring pickle. Di-ethylamine. (C2H5)2NH. Putrid meat extract. Tri-ethylamine. (C2Hj)gN. Decomposed cod-fish. Propylamine. CgHyNHg. Decomposing cod-liver. Butylamine. C^HgNHj. Do. do. Amylamine. CjHjjNHg. Cod-liver oil. Diamines of the Fatty Acid Series. Putrescine, or Tetramethylene-diamine. C^Hj2^2* Putrid horseflesh. Cadaverine, or Pentamethlyene-diamine. CjHj^Ng. Putrid fish and blood. NeMridine. CjHj^Nj. Putrid meat, albumin, gelatin. Saprine. CjHj^^Ng- Decomposed flesh. Guanidines. Methylguanidine. C^HyNg. Putrid horseflesh and beef. Aromatic Ptomaines, free from Oxygen. Collidine. CgHjjN. Putrid fish and putrid gelatin. Parooline. CgH^glSr. Putrid horseflesh after several months. Corindine. CjqHjjN. Putrid cuttle-fish. Di-hydrocollidine. CgH^jN. Putrid fish and horseflesh. Oxygenated Ptomaines. Neurine. CsHjgNO. Putrid meat on fifth or sixth day. Choline. CsHjgNOg. Accompanies neurine. Muscarine. CjHjjNOg. Putrid fish. Betaine. CjEjiNOj. In mussels (leucomaine). 224 FLESH FOODS. Homoj)iperidinic Acid. CjHj^jNOg. Decomposition of meat fibrin. Mytilotoxine. C^HijISrOj. In poisonous mussels (? leuco- maine, cf. p. 222). Mydatoxine. CjHjgNOg. Putrid horseiiesh after nine to fifteen months. Methylgadinele. C,X,NO,. [ ^^^"'^ ^^^' especially cod. Unnamed Base of Brieger. CyHjj-XOg. Accompanies myda- toxine. Aromatic Oxygenated Bases. Tijrosamines. Cj.HgN"0 ; CgH^jNO ; CgHjjNO. Decomposing cod-liver. Mi/iline. C^HjjNO. Decomposing human flesli. Symptoms of Ptomaine Poisoning. — The usual symptoms of ptomaine poisoning are dilation of the pupil of the eye, followed liy its contraction, feeble pulse, slow respiration, fever, loss of muscular oontractibility, stupor, convulsions, and death. The loss of the power of contracting the muscles, even under electrical stimulus, is remarkable, and is a characteristic symptom of poisoning by muscarine, a ptomaine which is found both in putre- fying flesh and in poisonous mushrooms. The ptomaines vary considerably in their physiological action, some being quite inert, while others are fatal even in small doses. The symptoms of flesh poisoning probably vary in kind and degree with the nature and quantity of the bases present, some of which may modify to a greater or less extent the action of the others. Of the monamines formed during the putrefaction of flesh, the methylamines and ethylamines are only moderately poisonous, tending to produce fever ; hutylamine in large doses produces con- vulsions and muscular paralysis ; and amylamine, which is very poisonous, causes dilation of the pupils of the eye and con- vulsions. The diamines (putrescine, cadaverine, neuridine, and saprine) are either physiologically inert or at most only slightly poisonous. Cadaverine is said to produce inflammation of the mucous membrane. Methyl-guanidine, which may be taken as representative of the guanidine ptomaines, is exceedingly toxic. It produces dilation of the pupils, convulsions, and death within twenty minutes, when injected into a small animal. Of the aromatic non-oxygenated ptomaines, collidine, parvoline, corindine, and di-hydrocollidine are all extremely poisonous. Corindine resembles curare in its efiects, causing paralysis. BOTULISM, OR SAUSAGE POISONING. 225 Bi-hydrocolRdine produces torpor, muscular paralysis, and convulsions. Of the better-known oxygenated ptomaines, neurine produces salivation, contraction of the pupil of the eye, sudden convulsions, and death. Choline resembles neurine in its physiological action, but is much weaker. Muscarine is exceedingly toxic, and in small doses produces salivation, contraction of the pupil of the eye, diarrhoea, convulsions, and death. The action of atropine is antagonistic to the three preceding ptomaines, and is used as an antidote. Betaine is non-poisonous. Mydatoxine is moderately poisonous. In large doses it causes diarrhoea, redness of the eyes, convulsions, and death. Gadinene is not very poisonous, but methylgadinene in sufficiently large doses produces symptoms of paralysis. An unnamed base of Brieger (C7HJ5.NO2), which was found accompanying mydatoxine in putrid horseflesh, has poisonous properties resembling those of curare. Botulism or Sausage Poisoning. — Like the attacks of trichinosis, cases of botulism have been most frequent in those parts of Germany where, as in Saxony, raw ham and raw sausage are most widely eaten. Sometimes the poisoning has been wholesale, as in the Chemnitz cases, where, in 1879, 241 individuals were poisoned by Mettwurst, and where, seven years afterwards, 160 persons were poisoned in the same way. Ostertag * mentions smaller outbreaks of the same kind since 1886, as, for instance, in Dresden (11), in Gerbstadt (over 50), and in Gera (30). The characteristic symptoms of pure botulism appear after a period of incubation of from eighteen to forty-eight hours. They commence with a feeling of uneasiness and pressure in the stomach, followed by vomiting and, occasionally, diarrhosa, with faintness, disturbance of the vision, muscular flacoidity, and collapse. When the case ends fatally death results in from four to eight days. When the toxine of B. hotulinus is the sole contributing cause of the illness, fever and mental disturbances are not among the symptoms. The mortality is very high, and, according to Senkpiehl, out of 412 cases recorded between 1789 and 1886 there were 165 deaths. Eber regarded both sausage poisons and ptomaines as toxigenic substances, not toxines. Under the term ' toxigenes ' he grouped those chemical products which, on injection into an animal, are not poisonous until they have been modified by the vital activity of the cells. He compared them with certain inorganic substances, such as sodium iodide, which, when injected into an animal, produce no ill eiFects for some six or eight hours. * Loo. dt., p. 502, Schneidemiihl, Gmt.f. Bakt., 1898, p. 577. P 226 FLESH FOODS. The origin of the poison remained unexplained for years, although it had long been recognised as distinct from that derived from ordinary putrefaction. Hilger * was the first to isolate from the intestines of six persons who had died from sausage poisoning a semi-fluid substance with properties resembling those of curare, and Tamba found a similar substance in liver sausage exposed to the air. Haupt believed that the disease was produced by the decom- position products formed by B. proteus mirahilis, but Ostertag pointed out that the symptoms of botulism did not agree with those produced by the inoculation of cultivations of that micro- organism. In 1895 van Ermengem isolated, from the body of a victim to sausage poisoning, an anaerobic bacillus, the cultivations of which produced the same symptoms. The characteristics of this bacillus, which was never found in putrefying substances, are given on page 278. Brieger and Kempner t have recently isolated from pure cultiva- tion of B. hotulinus a toxine which they regard as closely related in chemical composition to the toxines of diphtheria and tetanus. The dried toxine kept well, and was found to produce all the symptoms of sausage poisoning. From putrefying liquids or flesh no poisonous products with the same pathogenic properties could be isolated. The symptoms caused by products of the coli species, to which flesh poisoning has often been attributed, had no specific effects, and the cultivations of Gaertner's B. enterifidis produced only very slight symptoms. The toxine of B. botulinus is rendered inactive by being heated to 60° or 70° C. Kempner J found that by injecting gradually-increasing doses of the toxine into goats the animals were rendered immune, and that guinea-pigs treated with the blood serum of the immune goats were made capable of withstanding a dose of the toxine 100,000 greater than one which, under other circumstances, would have been fatal. * Konig, NaTir. Genussm., ii. p. 103. t Cent./. BaU., 1898, p. 619. X Znt. f. Hyg., 1897, xxvi. p. 481. CHAPTER XII. THE ANIMAL PARASITES OF FLESH. To give even a brief account of all the internal parasites found in different animals would require much more space than can be spared for it here, so that, with a few exceptions, the various organisms described in this chapter will be limited to those connected directly or indirectly with flesh considered as^ human food. Internal parasites, or Entozoa, may be defined as lower organ- isms, which either in an immature or adult condition inhabit the tissues or canals of different organs, or of the muscle or skin of higher animals, either in a free or encysted state. They may be grouped into three main divisions : — Frotozoa. — Low organisms whose bodies are composed of con- tractile tissue and are usually without definite structure. Infusoria. — Microscopic organisms provided with mouths, or at least suction tubes, such as, for example, Cercomonas intestindlis, found by Davaine in the excreta of a cholera patient. HelTtiinthia, or true intestinal worms. Of the first class the parasites in the sub-order of Sporozoa are of primary importance in the examination of flesh and flesh pro- ducts, and of the third class the three orders — Cestoda, or tape- worms ; trematoda, or flukes ; and nematoda, or round worms — likewise require special attention. SPOROZOA. These form a class in the sub-kingdom of Protozoa. They are unicellular organisms devoid of definite progressive organs (pseudo- podia or cilia), but often provided with an organ of attachment. Their food is absorbed by endosmosis, and their whole lives are spent as parasites. When adult they reproduce their species by the formation of spores (jpsorospermix) in their interior. Within these spores are formed small sickle-shaped bodies, from which are 228 FLESH FOODS. developed new parasites. The organisms of this class most com- monly met with in the examination of flesh are the so-called 'psorosperm saccules,' the formations known as ' Miescher's tubes,' and the coccidia with which rabbits are often affected. 'Psorosperm Saccules.' These sporozoa, first discovered by J. Miiller, are found in the muscle and on the skin and gills of fishes, and when visible to the naked eye have the appearance of small white specks. They vary very considerably in size, some being microscopic, while others are several millimetres in diameter. Miescher's Tubes {Synchitrium Miescherianum). These curious formations derive their name from Miescher, who first noted their occurrence in the muscles of a mouse. They have since been found to be widely distributed, and are frequently met with in the flesh of the pig, ox, sheep, deer, and other animals. In the normally extended muscle they have the appearance sho^^'n in the accompanying figures, but when the muscles are freed from Fig. 20.— a single Miescher Tube in a. muscle fibre. More highly magnified. (Leuckart. ) Fig. 19. — Preparation of muscle containing Miescher's Tubes. ( Leuckart. ) their insertions and the fibres contract, the tubes become broader and shorter. They have a thick exterior wall of cuticle, and contain a tough matrix of protoplasm, in which are small bean- shaped granules, O'Ol mm. in diameter. In the younger and smaller tubes (0-7 to 1 mm.) transparent balls (probably spores) may often be observed. Miescher's tubes are usually classed among the sporozoa, but there is some doubt on the point, since no movements have been observed in the stage of development. Perroncito, in his experi- MIESCHER'S tubes. — COCCIDIA. 229 ments on the action of heat on various parasites (p. 248), found that these organisms never showed any signs of movement as the temperature rose. On the other hand, Leuckart * states that by feeding a pig which was free from the tubes on iiesh containing them, he succeeded in infecting the animal, and its muscles were subsequently found to be full of tubes. So far as is known these organisms are without pathological significance. They can be readily stained by means of carmine or methylene blue. Marpmann recommends a counter-stain composed of phloxin red 1 part, and methylene blue 1 part, in dilute alcohol. The section from the flesh is pressed between cover glass and dipped in the stain for ten minutes, then washed with alcohol and water, and examined under the microscope. In this way the organism is stained blue and the muscular fibres red. Coccidimn Oviforme. This, organism may be taken as a representative example of the coccidia. It has been found in invertebrata (snail, etc.), in various mammalia, and in man, but it is most frequently met with in rabbits, where it produces what is known as the 'coccidial disease.' The livers of the infected rabbits are often found permeated with white nodules, some of which attain the size of a nut ; and on section a cheesy mass exudes, which contains innumerable numbers of the coccidia. Sometimes the disease becomes epidemic, and the whole of the rabbits in a warren become infected. The secretions of the liver and bile are interfered with, and the tissue of the glands destroyed. The animals become thin and sick, then shortness of breath and convulsions ensue, and finally death. These sporozoa are also known as ' egg-shaped psorosperms,' a name which rightly belongs only to the spores formed within them. The Fig. 21.— Coccidia in the Liver of coccidia vary in size from 0-35 to * Rabbit, one showing psoro- 0-37 mm in length, by 0-015 to 0-02 ^^^^j^' ^ ««<'• mm. in breadth. In the earliest stage of their life history these and other coccidia are found in a free state in the epithehal cells, but towards the end of the period of growth they become enveloped in a firm shell, and leave their resting-place and generally their original host. The granular protoplasm is condensed into a mass in the * Human Parasites, p. 199. 230 FLESH FOODS. centre of the capsule, and spores are formed, each containing a granular ball and a sickle-shaped body. In the case of the Coccidium oviforme the spores are only produced after expulsion with the faeces from the body of the host, and the further develop- ment proceeds in moist surroundings outside. The spores are round or elliptical, and have a rather thin wall. According to Leuckart * they are invariably four in number. THE CESTODA. This class of parasites includes the tapeworms and allied organisms. They are flat worms devoid of mouth or alimentary canal. The ' head ' or nurse (scolex) is provided with two or more suckers, and in many cases with curved hooks of attachment, by means of which it fastens itself on to the intestinal membrane of its host, which is usually a vertebrate animal. Here it increases joint by joint, forming a long ribbon-like colony, which re- mains attached to the head for a considerable period. The individual sexual segments (proglottides) increase in size, and be- come more mature or ' ripe ' as they become further removed from the head by the formation of other segments. The ripe joints are expelled from the body of the host, and the embryo which each contains becomes a bladder-worm (Cysticercus or Cysticercoid), usually in the muscles or organs of another animal or inter- mediate host. Here it remains quiescent until introduced into the intestine of a subsequent host, where the head of the larva attaches itself to the membrane, and a new tapeworm is produced. Classification of Tapewoems. Leuckart t gives the following scheme of classification of representative CestoJa : — FAMILY: T.aENIADiE. DIVISION I. Cystici (Cystic tapeworms). Sub-genus. — Cystotsenia (Leuckart). 1. Taenia saginata. 2. T. sohum. 3. T. acanthotrias. 4. T. marginata. Sub-genus.— 'EchmococcifeT (Weinland). 5. T. echinococcus. * Zoc. cit., p. 202. t Human Parasites, p. 390. CLASSIFICATION OP TAPEWORMS. 231 DIVISION II. Cystoidei (Ordinary tapeworms). Suh-genus. — Hymenolepis. 6. T. nana. 7. T. flavo-punctata. Sub-genus. — 1 8. T. madagasoariensis. Sub-genus. — Dipy 1 idium. 9. T. cucumerina. FAMILY : BOTHRIOCEPHALIDa:. Genus. — Bothriocephalus. 1. B. latus. 2. B. cristatus. 3. B. cordatus. 4. B. liguloides. Usual Hosts of Some Tapbworms. The following table shows the hosts of some of the better-known bladder-worms and their related tapeworms : — Larva. Cysiicercus cellu- losx, C. iovis, C. acantJwtrias, G. tenuicollis, EcMtwcoccus hominis, G. fasdolaris, G. pisiformis, Cosnurus cere- Cysticercus T. cMumerinse, Larva of Bothrio- cephalus latus, „ B. cordatus. Host. Swine, dog, bear, deer, rat, ape, man. Ox, goat (experi- ment), giraffe. Man, ox (prob- able). Swine, rumi- nants. Ox, sheep, swine, man. Mouse. Hare, rabbit. Sheep, ox, sc[uir- rel. Dog-louse (Trioh- odectes canis). Pike and other river fish. Probably marine fish. Tapeworm. Tasnia solium. Host. Man. T. sagiTUtta, Man. T. aeanthotrias, T. marginata, Kot known, prob- ably man. Dog, wolf. T. ecMnococcus, Dog. T. crassicollis, T. serrata, T. cosnurus. Cat. Dog. Dog. T. cucumerina, Dog, oat, man. Buthrioceplmlus latus, B, cordatus. Man, oat (experi- mentally). Dog, man. (?) T. tenella. Man (?). Cysticercus ovis, Sheep. Family I. — The Taeniadse. — The tapeworms in this branch of the Cestoda have small spherical or pear-shaped heads supported and moved by a muscular proboscis, the rostellum, and provided 232 FLESH FOODS. ■with four suckers for attachment, and usually with one or more circlets of hooks. The division of the individual segments is well marked, and each retains its enclosed eggs until the proglottis itself is destroyed. The Teeniadae fall naturally into two divisions : — I. Cystic tape- worms, which at a certain stage of their growth as larvae form bladder-like cysts containing liquid {hydatids). II. Ordinary tape- worms, in which the embryonic body is solid or nearly solid. I._CYSTIC TAPEWOEMS. These can be further subdivided into two more groups. A, " Those in which the head arises within the embryonic bladder," and B, " Those whose heads are budded oflf from special brood cap- sules attached to the inner surface of the bladder."* With the exception of T. saginata and T. solium, all the tapeworms of Group A are found in carnivorous animals. T. echinococcus is representative of group B. Group A. Tsenia saginata. — General Characteristics. — This tapeworm, also known as T. medio-canellata, T. lata, and T. dentaia, is common throughout Europe, Asia, and Africa, and is the tapeworm most frequently met with in Bavaria, Hungary, Italy, and Turkey. When full-grown it is about 4 metres in length in its contracted state, and from 7 to 8 metres icmEniMiffiiH] mmmmmmmmmmms^i^^^^^^^^^^^ (After Zeuckart. ) Natural size. when extended. It usually has from 1200 to 1300 segments, of which from 150 to 200 are 'ripe' proglottides. The middle segments measure from 12 to 14 mm., and those of the neck seldom less than 1 to 1'5 mm. The head is large (1'5 to 2 mm.), and has a flattened crown, in which is a hollow depression. * Leuokart. CYSTIC TAPEWORMS. — T. SAGINATA. 233 It has four suckers, but is devoid of hooks (figs. 23 and 31). Each ripe proglottis is capable of holding about 3500 eggs (Leuckart). The entire colony of proglottides is renewed every three months, and Cobbold* estimates that a single tapeworm can thus distribute annually twelve million eggs. Cysticercus Bovis. — The bladder-worm of T. aaginata is found almost exclusively in the muscles of the ox, cow, and calf, and most of the attempts to rear it in other animals have been un- successful. Zenker, however, claims to have succeeded in the case of the goat, and it has also been known to occur in the giraffe. It is most frequently met with in the facial muscles, and Fig. 23. — Head of Cysticercus of T. saginata. x 25. (After Leuckart. ) Fig. 24.—' Measles ' in Beef. Two- thirds of tlie natural size. {E. Mitchell.) then in those of the heart and tongue, while other muscles (neck, breast, etc.) are comparatively free. It originates by the animal swallowing a ' ripe ' proglottis (or its eggs) which has been expelled from the body of the host of the parent tapeworm. In about eighteen weeks the eggs de- velop into completely formed bladder-worms, which, however, continue to grow for about ten weeks. When full grown each * Parasites of Man, p. 12. 234 FLESH FOODS. S B^ envelops itself in a long oval cyst from 3 to 5 mm. in diameter. This contains a transparent fluid, within which the retracted head of the worm can be distinguished. The head resembles that of the sexually complete tapeworm in being provided with suckers, but no hooks. It remains quiescent in the cystic state until the animal dies or is killed and the flesh eaten by man, when it attaches itself to the intestines by means of the suckers, and completes its development. 'Measles' in Beef.— The muscle containing the encysted bladder - worms, which resemble little white knots, has often been termed 'measly' from its appearance (fig. 24). 'There is usually a thick well-developed connective tissue around the cysts, and not infrequently the worm is found dead, and the cyst filled with caseous or calcareous matter. When, too, the fluid in the cyst is turbid, instead of clear and limpid, it is probable that the parasite is no longer living. Beef containing hydatids is only danger- ous in the raw or imper- fectly cooked condition. ' Measly ' beef is very prevalent in India, but is not common in this country. Taenia soUma. —General Char- acteristics. — This tapeworm is smaller and contains fewer segments than T. suginata. In an extended state it is from 3 to 3-5 metres in length, but when contracted, as seen in preserved specimens, its length is usually less than 2 metres Its greatest breadth is about 8 mm. It 8 a o Pk CYSTIC TAPEWOEMS. — T. SOLIUM. 235 usually has about 850 segments, of which from 80 to 100 are ' ripe.' It has a spherical head, about the size of a pin's head. Fig. 26. — Portion of section of Proglottis of Tapeworm (Tsenia solium). X 42. (After B. M. Prideaux.) provided with four prominent suckers, and from twenty-six to twenty-eight hooks. The apex is often marked with traces of a black pigment (fig. 31). As in the case of T. saginata, each proglottis, after leaving the parent colony, is capable of acting more or less like an independent organ- ism (figs. 25 and 26). The term ' com- mon tapeworm ' is used collectively to indicate both this and the preceding tapeworm. Accord- ing to Leuckart, Jews are free from T. solium (of the pig scolex) but are as Fio- 27.— Section of ripe Proglottis of T. soZmm, with much infected with Sexual Organs. x8. (Mi.r B. M. Prideaux.) T. saginata as the rest of the community. The uterus of a free proglottis is a characteristic structure (figs. 27 and 31). The larva of this tapeworm {0. celluloses) is found most fre- quently, although by no means exclusively (c/. Table, p. 231) in the muscles of the pig, where it produces the well-known ' measles ' 236 FLESH FOODS. of pork. Its origin and development take place in a similar manner to that of the ox-hydatid, but it is much more dangerous from the fact that the bladder-worm and tapeworm are capable of living in the same host, and thus, in the case of man, auto- infection with the hydatids, which produce much greater organic disturbances than the tapeworm, is by no means impossible. ' Measles ' in Pork. — When eaten by a pig, the covering of the eggs of the tapeworm is dissolved by the gastric juice, and the embryo, piercing the wall of the intestine, chooses a suitable place in the muscle, and is gradually trans- formed into a hydatid, on the inner wall of which the head is developed. After three weeks the bladder is the size of a pin's head, and continues growing until the ninth week, when it is as large as a pea, and the head, on which the suckers and hooks can now be distinguished, is as large as a pin's head. After three months the neck is developed, and the larva is ready for transference to its subse- quent host. It now becomes en- veloped in a capsule of connective tissue, and remains quiescent until the animal dies or is killed. Unlike the trichinx, which imbed themselves in the muscular fibre, the hydatids prefer the con- nective tissue between the fibres. Among the parts most fre- quently infected are the paunch, heart, tongue, neck, diaphragm, and inner side of the thigh. They are least frequently found in the liver, lungs, and intestine. The frequent occurrence of the hydatids in the tongue often enables the owner of a pig to discover them in the living animal, and in Germany such infected swine are often promptly sent off to some out-of-the-way place where there is no inspection of meat, although the practice is forbidden by law.* The cysts formed by the swine bladder-worms are somewhat smaller and rounder than those of the ox hydatids, and have not so grey an appearance. Calcareous degeneration also occurs with much less frequency. The living hydatid contains a clear transparent fluid in which the white head of the parasite is seen. The walls of the bladder are composed of a semi-transparent mem- brane, and around this the connective tissue of the flesh in which * Fisclioeder, loc. cit., p. 164. Fig. 28.— 'Measles' in Pork. About two-thirds of the natural size. (After E. Mitchell.) SWINE CYSTICERCI. 237 the worm is imbedded becomes thickened, forming an additional layer, so that the cyst has a greyish opalescent appearance (figs. 32 and 33). The head, retracted within the bladder, is Fig. 29. — Swine Cystioerous with Fig. 30. —Ripe egg of Tmnia head protruded, x 3. (After solium, a, albuminous enve- Leuckart.) lope ; b, remains of yelk ; c, covering of the embryo ; iO^\.YLCl. Physiologically it is inoffensive. BUTALANINE, or AMIDO-VALERIC ACID [C5H11NO2 or (NH2)C^Hs.C00H] accompanies leucine in the products of pancreatic digestion. Its hy- drochloride is insoluble in ether, but very soluble in water. It is not precipitated by platinum chloride. It is non-poisonous (see p. 184). S-AMIDO-VALERIC ACID [NH2.CH2.CH2.CH2,CH2.COOH]. This homologue of butalanine was isolated by E. and H. Sal- kowski from the products of the bacterial decomposition of albumin. It is a crystalline body, fairly soluble in water, slightly soluble in alcohol, and insoluble in ether. It melts at 156° C. AMIDO-ACID PTOMAINES. 321 Its hydrochloride [CjHjjNOg.HCl] forms stellar crystals, which are non-deliquescent. The platinochloride is yellow and crystal- line (c/. p. 315). LEUCINE, or AMIDO-CAPROIC ACID [CgHisNO^ or NH2.C,H,o.COOH]. This is a common constituent of putrefactive products, and is also produced in gastric and intestinal digestion. Its hydrochloride is not precipitated by phosphotungstic acid or platinum chloride (see pp. 183 and 185). AMIDO-STEARIC ACID [Ci8H35(NH2)02]. This was found by Gautier and Etard in putrefied flesh. The free acid is insoluble in water, but very soluble in hot alcohol. It crystallises in needles which melt at 63° C. When heated at 140° C. it loses water, and is apparently converted into its anhydride C^gHg^NO. OTHER LEUCINES and LEUCEINES are invariably found in the putrefaction products of meat or fish, such as more complex compounds of the general formula C„H,„_iN02. (6) Amido Acids of Aromatic Series. TYROSINE [CgHjiNOj] or^j-HYDOXYPHENYL-a-AMIDO PROPIONIC ACID I- /(CHo.CKNHa.COOH) L^ciiA OH. This is invariably present in putrefactive products, and accom- panies leucine as a normal constituent of the pancreas, liver and blood. The hydrochloride is crystalline, and dissociated on contact with water. The platinochloride is very soluble and deliquescent. PHENYL-AMIDO-PROPIONIC ACID [C6H5.CH2.CH.(NH2)COOH] was found by Nencki in the products of the action of anaerobic bacteria on fibrin. 322 FLESH FOODS. PTOMAINE [Ci^H^gN^OJ. Guareschi isolated a substance with this formula from putrefied fibrin. It forms crystalline lamellse, soluble in water and alcohol, and melting at 247° to 250°. The platinochloride forms rosette-shaped crystals. The hydro- chloride is precipitated by phosphomolybdic acid (yellow mass), and by picric acid (reddish-yellow precipitate). Gold chloride gives a precipitate which is instantly reduced. It gives the Prussian blue reaction. Guareschi considered this compound to be an amido acid, but Gautier doubts this conclusion, since it gives precipitates with phosphomolybdic acid and with Bouchardat's reagent. IX. — Carbopyridic Acids. MOERHUIC ACID [CgHi3N03]. This was isolated by Gavitier from cod-liver oil. It is a feeble acid, which is insoluble in ether, and forms salts with alkalies. Its platinochloride crystallises in soluble prisms. The auro- chloride is amorphous. Physiologically it acts as a stimulant to the appetite, and is non-poisonous. Gautier considers that its probable constitution is CH HC,-r-= \COH H.,C C(C3He)C00H. PATHOLOGICAL PTOMAINES. In addition, to the compounds described in the preceding pages, numerous basic substances have been isolated from the urine of patients suffering from different febrile diseases ; but these, being foreign to the subject of this book, need only be alluded to here. INDEX. Abnokmal colorations of flesh, 70. moisture iu flesh, 79. Absorption of water by flesh, 142. Acetyl values of animal fat, 61, 95. Acid, asellic, 27. boric, as preservative, 119. fatty, 27. hydrochloric, compounds with proteids, 160. inosinic, 19. jecorio, 27. lactic, 20, 132. linolenio, 25, 27, 101. linolic, 25, 27, 101. oleic, 25, 27, 100. phospho-carnic, 6, 82. phospho-molybdic, as proteid precipitant, 174. phospho-tungstio, as proteid pre- cipitant, 167. picric, as proteid precipitant, 174. salicylic, as preservative, 122. stearic, 26, 27, 54, 56, 99. sulphuric, decomposition of pro- teids by, 176. Acid 'fermentation,' 62. Acid reaction of flesh, 19, 62, 73, 74,75. value of fat, 95, 133. Acidity of sausages, 132. Acids, amido-, 17, 320. fatty, 27, 96. of dead muscle, 1 8. Actinomycosis, 295. Adamkiewicz's proteid reaction, 161. Adenine, 12. Adeno-sarcine, 13. Adipose tissue, 24. Albuminates, 152. Albuminoid substances, 153, Albuminous substances, 148. Albumin-peptones, colour reactions of, 162. Albumin, 152. acid-, 152. action of certain dyes on, 143. alkali-, 153. digestion products of, 179. in meat extracts, 187. of serum, 41. Albumins I. and II., 171, 205. Albumoid, 29. Albumoses, 154. composition of, 181. food value of, 191. in meat extracts, etc., 191, 201. injection of, into the blood, 191. old names for, 155. separation and estimation of, 156, 171, 192, 195, 198, 202. Alkali albumins. See ' Albuminates. ' Almen's tannin reagent, 174. Alterations in colour of flesh on heating, 142. American bacon, composition of, 112. Amide nitrogen, determination of, 82. Amido-caproic acid, 321. Amido compounds in digestion, 183. compounds in putrefaction, 320. Amido-stearic acid, 321. Amido- valeric acid, 315, 321. Amines, 300. Ammoniacal nitrogen in meat extracts, 192, 198. Amphi-kreatinine, 11. Ampho-albumoses, 179. Ampho-peptones, 159, 180. Amphoteric reaction of flesh, 75. Amylamines, 302. Anchovies, salt, 108. Anchovy paste, 118. Animal alkaloids, 217. fat, composition of, 25. parasites in flesh, 211, 227. Animals, flesh of different, 46. flesh of domestic, 48. flesh of invertebrate, 67. flesh of wild, 60. Anthrax, bacillus of, 212, 287. flesh infected with, 288. toxine of, 213. Anti-group in proteids, 159, 176, 178. Antipeptones, 159, 176, 179. Antiseptics, preservation by, 76, 118 Antweiler's peptone, 190, 203. Appert's process of sterilisation, 112. Armour's extract of meat, 197. Artificial coloration of flesh, 71, 142. digestion experiments, 86. Asellic acid, 27. Aselline, 310. 324 INDEX. Aspartic acid, 184, Assea' flesh, 56, 135. Atmidalbumin, 177. Atmidalbumoses, 179, 189. Atropine as an antidote to ptomaine I)oi3oning, 225, 312, 313, 314. Auto-infection of animals with basic products, 217. Avian tuberculosis, 294. Bacilli of phosphorescent flesh, 272. of rabbit septicseraia, 281. Bacillus anthracis, 212, 287. botulinus, 226, 278. coll communis, 226, 276. enteritidis, 269, 275. of fish cholera, 221. of fowl cholera, 283. of glanders, 286. of grey flesh, 272. of hog cholera, 282. of malignant oedema, 284. of quarter-evil, 288. of sausage poison, 278. of swine erysipelas, 283. of swine fever, 281. of tetanus, 212, 284. of tuberculosis, 289. proteus niirabilis, 276. typhosus in oysters, 296. Bacon, composition of. 111, 112. Bacteria, action of cold on, 103. chromogeuic, 115, 270. decomposition of proteids by, 186. flesh rendered poisonous by, 220, 222, 225, 278. influence of salting on, 108. influence of smoking on, 110. in sausages, 269. in shell-fish, 296. of normal flesh, 269. of septicemia, 281. pathogenic, 279. phosphorescent, 272. putrefactive, 274. species of, in flesh, 265. thermal death points of, 212. Bacterial coloration of flesh, 142, 270. products of putrefaction, 277. toxines, destruction by heat, 213. Bacteriological methods of examining flesh, 265. Balistes or 'file-fishes,' 220. Barracudas, 219. Bases, flesh, 187, 192. Bases, kreatinic, 8. xanthic, 11. Bear's flesh, composition of, 60. Beef, characteristics of, 49, 105. digestibility of, 87. essence of, analyses, 197, 200. fat, 50. fluid, and peptones, 188. sausages, 128. tea, 187, 200. See ' Ox.' Betaine, 8, 218, 222, 225, 314. Bilirubin, 42. Birds, fat of, 63. flesh of, 60. Biuret reaction, 161. Blackcock, fat of, 25, 63. Black-puddings, 128. Blood, characteristics of, 33. coagulation of, 33, 41. composition of, 43. fibrin, 41, 181. gases in, 42. identification of, in stains, 44. meal, 107. of different animals, 34, 38. of invertebrate, 45. plasma, 40. quantity of, in animals, 32. reaction of, 33. spectroscopioal examination of, 39, 44. ' Blown ' meat, 77. Bone, mineral matter in, 31. structure and composition of, 29. Boric acid, preservation by, 119. Bothriocephalidse, 245. Bothriocephalus cordatus, 247. oristatus, 247. latus, 245. liguloides, 247. Bothriomycosis, 296. BotuIism(sausage-poisoning),226,278. anti-serura to, 226. Bovril, 196, 197, 199, 202. Brain sausage, 126. Brand'sessenceofbeef, analysesof,197. ' Braxy ' mutton, 53. Brieger's method of isolating pto- maines, 298. Bromine body, 184, Bromine, precipitation of proteids by, 169, 192. thermal value, 93. Bruylant'a analyses of meat extracts, 202. INDEX. 325 Bull beef, 49, 62, 78, 134, 141. bone of, 31. Butalaniue, 18, 320. Cadaveeine, 224, 304, Caffyn's liquor carnis, 197. Calcified muscle trichinae, 255. Calcium carbonate deposits in flesh, 259. Calculation of food value of flesh, 88. Calf, bones of, 31. composition of a, 49. diphtheria, 295. CalPs flesh, characteristics of, 51. mineral matter in, 21, 51. See 'Veal.' Canned meats, bacteriological examin- ation of, 117. chemical examination of, 115. chemical reaction of, 116. composition of, 113. manufacture of, 112. metallic contamination of, 116. poisoning by, 116. reaction of, 116. Carbon dioxide, in blood, 42. poisoning, influence on flesh, 71. Carbon monoxide hseraoglobin, 38, 39. poisoning, 38, 71. Carbopyridic acids, 322. Cardiac muscle, structure of, 1. Carmine in sausages, detection of, 144. Carnine, 16. Carnolin, 123. Carp, composition of, 65. determination of age of, 64. toxine in blood of, 221. Cartilage, structure and composition of, 28. Casein, antipeptone from, 159. Cat, characteristics of the fat of, 61. mineral matter in the flesh of, 21. Caviar, composition of, 109. examination of, 109. reaction of, towards litmus, 110. Cervelatwurst, 126, 127. Cestoda, 230. malformations of, 247. Charque, composition of, 104. Chlorine, determination of, in flesh, 80. Choline, 218, 225, 312. Chondrin, 29. Chops, mutton, composition of, 209. Chromogenic bacteria, 270. Cibil's meat extract, analyses of, 199, 201, 203, 204. Cibil's meat extract, manufacture of, 185, 190. Oirio's process of salting flesh, 107. Clupea thryssa, 219. Coagulated albumins, 162. Coagulation of blood, 83, 41. of muscle plasma, 5. of proteids by heat, 162, 163. Coccidium oviforme, 229. Cockle, composition of, 68. Cod, cooked, composition of, 210, 211. mineral matter in the bone of, 31. oil, 66. 'red,' bacillus of, 271. Cod-liver oil, 66, 67. Ooenurus cerebralis, 240, 248. Cold, action of, on bacteria, 103. destruction of cysticerci by, 249. preservation of flesh by, 102. CoUagene, composition and properties of, 153. in white fibres, 23. CoUidene, 308. Coloration of fiesh, artificial, 71, 142. bacterial, 142, 270. • Colour of blood, 33. of flesh, 4, 7, 142. reactions of albumin and gelatine peptones, 162. reactions of proteids, 160. Colouring matters, action of, on flesh proteids, 143. in sausages, extraction of, 143. of blood, 33. of muscle, 7. Compound albuminous substances, 163. Compressor used in examination of flesh for trichinae, 258. Connective tissue, 23. Consistency of flesh, 77, 89. Cooked flsh, composition of, 210. meat, composition of, 209. Cooking of flesh, 207. effect of, on animal parasites, 211, 248, 262. effect of, on bacteria, 211. eflectof.onbacterialtoxines, 213. loss during the, 207. temperatures reachedin, 214,262. Copper in canned meats, 117. in oysters, 68, 117. in blood of invertebrata, 45. Copper hydroxide, precipitation of proteids by, 170. 326 INDEX. Copper sulphate, precipitation of deutero-albumoses by, 157. Corindine, 308. Corned beef, analyses of, 113. preparation of, 112. Corpuscles, red, 33. white, 38. Cow, flesh of, 47. mineral matter in bones of, 31. See ' Beef.' Cow-pox, 289. Crab, flesh of, 67, 87. hsemocyanin in blood of, 45. Creosote in wood smoke, 110. Cruso-kreatinine, 11. Crustacea, 67. Cysticerci, 231. examination of flesh for, 260. influence of cold on, 249, 250. influence of heat on, 249. in ham, 250. malformations of, 247. position of, in flesh, 260. tests for living, 250. thermal death points of, 248. Cysticercoids, 244. Cysticercus bovis, 233, 248. cellulosEe, 235, 248. fasciolaris, 241. ovis, 242. pisiformis, 239, 248. tenuicolJis, 238, 248. Cystic tapeworms, 232. Cystoidei, 244. Decomposition of flesh, 102, 186. Deer, fat of, 63. flesh of, 60. Denuclbins, 171, 174, 205. Deutero-albumoses, 156, 157, 176. Deutero-proteoses, 151, 181. Diamines, 223, 302. Digestibility of different kinds of flesh, 85, 87. Digestion by papayotin, 185. experiments, 86, 87. pancreatic, 182. peptic, 179. products, composition of, 181. proteids absorbed in, 191. Digestive proteolysis, 179. manufacture of peptones by, 190. Dihydrocollidine, 308. Dihydrolutidine, 309. Diodon, 219. Diphtheria, see 'Calf diphtheria,' ' Fowl diphtheria.' Distomum hepaticum, 251. lanceolatum, 251. of muscle, 261. Dog's fat, characteristics of, 61. Domestic animals, flesh of, 48. Double refraction of muscle, 4. Dragendorft's method of extracting ptomaines, 300. Dried fish, 107. Drying properties of animal fats, 25. Duck fat, constants of, 63. flesh, composition of, 60, 61. Dysalbumose, 156- Ebee's hydrogen sulphide test, 73. test for putrefaction, 75. Echinococcus, bladder of, 243. in muscle, 260. thermal death point of, 248. Eel, flesh of, 65, 210, 211. Egg albumin, 149, 152. action of superheated steam on, 179. Elastic flbres, 23. ElastiD, 24, 29, 154, 182. Enzymes, action of, on proteids, 179. in blood, 41. in muscle, 6. Epidemic disease of deer and cattle, 281. Erbswurst, 126, 127. Ethylamines, 301. Ethylidene-diamine, 302. Extractives of meat, 7. estimation of, 192, 196. from different animals, 48. Extract of meat, analysis of, 192. composition of, 196, 197, 199, 203, 205. manufacture of, 186. peptones in, 196, 201, 206. physiological value of, 187. See ' Meat extract. ' Faensteinee's methods of separat- ing fatty acids, 97, 100, 101. Fat, animal, composition of, 25. beef, 60. distribution of, in the body, 24. estimation of, 83. horse, 68, 140. in blood plasma, 91. intermuscular, 140, methods of examining, 91. mutton, 61. INDEX. 327 Fat of birds, 61, 63. of fish, 64. of wild animals, 61, 63. Fatigae,effectof, onammals'flesh,217. Fatty acids in animal fats, 27. separation of saturated from un- saturated, 96. Fibres, elastic, 22. globulin, 41. white, 22. Fibrin of blood, 41, 149, 150, 181. of muscle, 5, 149. trypsin digestion,produotsof, 184. Fibrinogen, 40. Fish, cooked, composition of, 210. dried, 107. fat of, 64. invertebrate, composition of, 67. parasites in, 245. vertebrate, composition of, 65. Fish cholera, 221. Flesh bases, estimation of, 192, 195. bases in meat extracts, 187. bases, physiological value of, 187. peptones, analysis and com- position of, 192. peptones, manufacture of, 188. peptones, physiological value of, 190. phosphorescent, 272. powder, 106, 187, 193. See Summary of Contents and 'Meat.' Flounder, flesh of, 65. Flour in sausages, 130. Fluid beef, composition of, 177, 197, 199. manufacture of, 188. Foetal flesh, calves', 51. glycogen in, 136, 136. Food, flesh rendered poisonous by, 216, 219. influence of, on the flesh, 60. Food value of flesh, calculation of, 88. Foot and mouth disease, 289. Formaldehyde, action of, on flesh, 134. action of, on proteids, 175. as a flesh preservative, 123. detection of, 123. use of, in meat extract analyses, 199. Fowl cholera, 283. diphtheria, 295. Fowls, composition of flesh of, 60, 61. Fox fat, characteristics of, 61. Freibank, flesh sterilisation by the, 2 1 4. French sausages, 128. Frog, digestibility of, 87. mineral matter in flesh of, 21. muscle of, 3. Frozen meat, alterations in, 103. detection of, 104. Frying of meat, 209. Gadinene, 224, 316. Game, fleah of, 48, 60, 61. food value of, 89. over-hunted, 217. ripening of, 62. toughness of, 78. Gases in blood, 42. in muscle, 22. Gastric digestion, artificial, 86. decomposition of proteids in, 179. physiological experiments on, 87. products of, 181. Gautier's method of extracting pto- maines, 298. Gelatin, action of formaldehyde on, characteristics of, 154. composition of, 149, 200. decomposition of, by enzymes, 181, 185. decomposition products of, 181. estimation of, 169, 193. food value of, 188. formation of, 23. in meat extracts, 188, 202. peptones, 159, 161, 169. precipitation of, 154, 168, 171. Gelatose, 154, 181. German sausages, analyses of, 127. composition of, 126. Gerontine, 17, 218, 307. Glanders, bacillus of, 212, 286. fleshofanimalsinfected with, 286. thermal death point of the bacillus of, 212. Globe fishes, 219. Globulin of muscle plasma, 5. Globulins, 149, 152. of blood plasma, 40, 149. separation of, fromalbumins, 152. Glucose in blood, 42. in muscle, 20. Glycocoll, 17, 320. Glycogen, 20, 22. colour tests for, 134. estimation of, 136. in cat's flesh, 135. in dog's flesh, 135. 328 INDEX. Glycogen in horse flesh, 136. reaction, 134. Goose, fat, constants of, 63. flesh, composition of, 60. mineral matter in bones of, 32. smoked, 111. Gram's method of staining, 267. Grey flesh, bacillus of, 272. Grilled meat, 209. Gristle in sausages, estimation of, 133. Guanidines, 223, 307. Guanine, 13. Guareschi's base, 319. Guinea-pig, bones of, 32. haemoglobin crystals from blood of, 35. Haddock, cooked, 210, 211. fat of, 66. iso-kreatinine in, 10. Hsematin, 37, 142. Hfematin-acid, 37. Hsematoblasts, 39. Haematoporphyrin, 37. Hsemin, 37. crystals, 38, H. Haemochromogen, 37, 39. Hiemocyauin in the blood of molluscs, 45, 68. Hfemoglobin, compound of, with carbon monoxide, 38, 39. composition of, 149. crystals from blood, 35. derivatives of, 37. estimation of, 36. in blood, 34. in muscle, 7. reduced, 39. spectrum of, 39. &c'Met-,"Oxy-,'and'Pseudo- haemoglobin.' HBemolymph, 45. Haemometer, 36. Halibut, flesh of, 65. Halogens, precipitation of proteids by, 168. Ham, bacteria in, 270. Ham, borax as preservative in, 119. coagulation of proteids in, by heat, 163. composition of. 111. cysticerci in, 250. potted, 118. sausage, 127. trichinte in, 257, 264. Hare, fat of, 25, 63. Hare, flesh of, 60. Haut-gout, prgduction of, in game, 62. Heart, muscles of the, 1. Heat, action of, on animal parasites, 211, 229, 248, 262. action of, on bacteria, 212. action of, on bacterial toxin es, 21 3 . action of, on colouring matters of flesh, 142. ' Heating ' of game, 65, 73. Hehner value, determination of, 94. Hemi-albumose, 175. Hemi-group in proteids, 176, 179. Hemi-peptones, characteristics of, 166, composition of, 169, 181, Hen, digestibility of, 87. flesh of, 60, 61. Herring, cooked, 211. fat of, 66. flesh of, 65, 87, 89. pickle, 108. salt, 108, 211, smoked. 111. Hetero-albumoses, characteristics of, 156, 164. composition of, 181. Heteroxan thine, 16. Hexylamines, 302. Histohsematins, 7. Hog cholera, bacillus of, 212, 282. flesh infected with, 282. Homomorrhuine, 309. Homopiperidinic acid, 315. Horse, blood of, composition of, 43. Horse-fat, characteristics of, 58, constants of, 59. formation of cells, 139. intermuscular, 141. iodine value of, 140. Horse-flesh, action of formaldehyde on, 134. characteristics of, 58, detection of, in sausages, 133. estimation of glycogen in, 136. glycogen reaction with, 134. reaction of, with acetic acid, 134. reaction of, with potassium hydroxide, 134. statistics of the use of, 56. Hyaline cartilage, 28, Hyalogens, 153. Hydatids in beef, 234. in pork, 236. Hydrochloric acid, compounds of, with proteids, 160. Hydrogen sulphide test, Eber's, 73. INDiiX. 329 Hydropeptone, Merck's, 199. Hypoxanthine, 14. Infusoria, 227. iDJectioa of albnmoses and peptones, 191. Inorganic constituents of blood, 42. of bone, 31. of muscle, 21. Inosinic acid, 19. Inoslte, 20. ' Intoxication,' putrid, 224, 278. Iodine value, bromine - thermal method of determining, 93. Hiibl'smethod of determining, 92. of liquid fatty acids, 96, 98. Wijs' method of determining, 92. Iridescence of tlesb, 71. Iron, detection of blood in presence of, 44. in the blood, 36, 43. in the muscle, 21, 70. Iron acetate, precipitation of proteids by, 170, 173. Iso-kreatinine in the haddock, 10. Jecokic acid in cod-liver oil, 27. Juices of frozen meat, 104. of meat, changes in colour on cooking, 214. retention of, in sterilisation, 215. Kabeljau or dried stock-fish, 107. Kemmerich's meat extract, analyses of, 196, 198, 199. method of separating proteids, 200. peptone, composition of, 198, 203. peptone, manufacture of, 189. Keratin, characteristics of, 154. composition of, 149. Koch's comma bacillus, 220. peptone, composition of, 203. peptone, manufacture of, 189. Kreatine, 8, 167. Kreatinic bases, 8. Kreatinine, 9, 167. Kreatinine, amount of, in muscle, 9. food value of, 187. Weyl's reaction for, 10. Kuhne's method of obtaining muscle plasma, 5. Lactic acid in muscle, 20. in sausages, 132. Lacto-albumiu, 149. Lamb, composition of a, 49. Lamb's flesh, digestibility of, 87. Lard, constants of, 67. difference between Eurojiean and American, 56. Lead in canned meats, 117. Lead, acetate, precipitation of proteids by, 170, 173, 206. Lecithin, 18, 42, 43, 80, 218. separation of, 19. Lepierre's base, 319. Leuceines, 321. Leucine, 17, 183, 321. Leucocytes, 38. in green oysters, 68. Leucomaines (ptomaines), 218. formation of, 7, 217. neurinic, 8. physiological action of, 187, 217. Liebermann's proteid reaction, 161. Liebig's meat extract, analyses of, 174, 196, 197, 200, 203, 205. manufacture of, 186. peptones in, 196, 202, 204, 206. unclassified nitrogenous con- stituents of, 198, 205. See 'Meat Extracts.' Linolenic acid, characteristics of, 27. determination of, 101. in lard, 65. Linolic acid, characteristics of, 27. determination of, 101. in horse fat, 25, 58. in lard, 65. in ox-tallow, 101. Lipochromes, 7, 42, 46, 64. Liver flukes, 261. sausages, 125, 127. Lobster, digestibility of, 87. flesh of, 67. potted, 118. Lozenges, bovril, 196, 199. Lysatine, 184. Lysine, 184, 319. Mackekel, cooked, 210. flesh of, 65, 87. smoked. 111. Magenwurst, 125. Maggi's meat extract, 199. Magnesium sulphate, precipitation of proteids by, 165, 171, 174, 205. Malignant oedema, bacillus of, 284. flesh of infected animals, 284. Mallein reaction, 286. Mallet's method of determining amide nitrogen, 83, 167. Marennin, 68. 330 INDEX. 'Measles,' destruction of, 248. in beef, 234. in ham, 260. in pork, 236. Meat, action of formalin on, 123. animal parasites in, 211, 227. bacteria of, 212, 269. bases, 187, 192. biscuits, 106, 107. blown, 77. canned, 112. characteristics of good, 72. cocoa, 106. cooked, 208. digestibility of, 86. food value of, 88. frozen, 104. infected, 213. juices of, 104, 214. scheme for examination of, 89. treatraentof, with antiseptics, 76. Meat extractives, 7, 48, 192, 196. Meat extracts, added meat fibre in, 187. added salt in, 188. albumin in, 187. analyses of, 192. composition of, 196, 197, 199, 203, 205. flesh bases in, 187. food value of, 187. gelatin in, 188, 202. manufacture of, 186. methods of analysing, 192. peptones in, 196, 202, 204, 206. physiological value of, 187. unclassified nitrogenous com- pounds in, 198, 205. Meat juice. Brand's, 197. Valentine's, 197. 'Vitalia,' 197. Wyeth's, 197. Meats, potted, 118. Melanosis, 70. Melting-point of fats, 91. Merck's peptone, 175, 199, 203. Mercuric chloride, precipitatiou of pro- teids by, 167, 171, 173, 205. iodide, precipitation of proteids by, 174. Merlusine, 309. Metals in canned meats, 116. precipitation of proteids by salts of, 1 65. Methsemoglobin, 38, 39. Methylamines, 300. Methyl-gadinine, 317. Methyl-glycocoll, 17. Methyl-guanidines, 9, 224, 307. Mettwiii-st, 127. Micro-organisms, determination of the number of, in flesh, 267. Microscopical examination of flesh, 117, 142, 250, 257. Microtomes, 267. Miescher's tubes, 228, 259. action of heat on, 229. Millon's proteid reaction, 161, 162. Mineral matter in blood, 42. in bone, 31. in muscle, 21, in muscle, determination of, 79. Moisture in muscle, abnormal, 79. determination of, 79. Monamines, 223, 300. Morrhuamine, 319. Morrhuic acid, 322. Morrhuine, 309. Mucin, 24, 149, 153. Mucoids, 153. Mule's flesh, 56, 135. Murexide test for xanthine, 15. Muscarine, 223, 225, 313. Muscle, chemical composition of, 22. colouring matters of, 6, 7, 70. free acids of dead, 19. mineral constituents of, 21. non-nitrogenous organic con- stituents of, 7. proteid constituents of, 4. reaction of, 19, 75, 76. structure of, 1. Muscle distomum, 261. Muscle plasma, 5. Muscle ray-fungus, 259, 296. Muscle trichina, 254 Muscular fibre, determination of, 82. Mussel, flesh of, 67, 68. poisoning by, 221, 315. Mutton, ' braxy,' 53. characteristics of, 61. chops, 209. cooked, 208. digestibility of, 87. food value of, 88. Muttou fat, constants of, 54, stearic acid in, 54. Mydaleine, 317. Mydatoxine, 224, 225, 316. Mydine, 224, 318. Myogen, 5. fibrin, 5. INDEX. 331 Myohaematin, 7. Myoi)roteid, 6. Myosin, 5, 149. action of certain dyes on, 143. productsofthepioteolysisof, 181. Myosin-fibrin, 5. Mytilotoxine, 222, 315. Nematoda, 252. Neuridine, 17, 218, 222, 224, 305. Neurine, 218, 223, 225, 311. Neurinio bases, 311. leucomaines, 8. Nicomorrhuiue, 310. Niebel's method of estimating glycogen, 137. Nitre, action of, on hemoglobin, 144, 145. as a flesh-colour preservative, 107, 145. Nitrogen, amide, estimation of, 82. methods of determining, 80. Nitrogenous constituents of meat extracts, 192, 193. Non-striated muscle, 1. Nucleins, 6, 80. composition of, 6, 149. Nucleo-albumin, 4. action of certain dyes on, 143. Nutrient units of flesh, 88. Nutritive value of commercial pep- tones, 189, 191. of meat extracts, 187. Odour of blood, 33. of flesh, influence of sex on, 53, 78. Oleic acid, characteristics of, 27. Farusteiner's method of separat- ing, 100. in pig's fat, 56. Olein, 25, 27. Optical rotation of proteids, 163. Ossein, 31. Osseous tissue, composition of, 31. structure of, 29. Ostracion or truuk-flsh, 220. Ox, blood of the, 43. bones of the, 21, 32. composition of an, 49. Ox, cysticcrcus of the, 231, 233, 248. Ox-flesh, action of potassium hydrox- ide on, 134. characteristics of, 49. composition of, 47, 49, 50, 105. digestibility of, 50, 86. extractives from, 48. See 'Beef.' Ox tallow, 50. Ox tongue, smoked, 111. Oxygen in blood, 42. Oxyhaemooyanin, 45. OxyhsEmoglobin,characteristicsof,34. composition of, 35, 149. crystals, 34. estimation of, 36. identification of, 35. separation of, 34. spectrum of, 36, 39. Oysters, composition of, 68, 210, 211. copper in, 68, 117. green, 68. hsemolymph of, 45, 68. liquid in, 67. pathogenic bacteria in, 296. phosphorus in, 68. Palmitic acid in pigs' fat, 56. ohai'acteristios of, 27. Palmitin, 27. Pancreatic digestion, 86. action of, on proteids, 182. experiments with, 86. Pancreatic peptones, composition of, 199, 203. manufacture of, 190. Papayotin, proteid digestion by, 185. manufacture of commercial pep- tones by, 185, 198. Papayotin peptones, analyses of, 203. Paraglobulin(serumglobuliu), 41,149. Parasites, animal, action of cold upon, 249, 261. action of cooking upon, 211, 248. actionofputrefactiouon, 249,263. detection of, in flesh, 250, 257. in flesh, 211, 227. influence of salting on, 263. influence of smoking on, 250, 263. thermal death points of, 211, 248, 261, 262. Paraxanthine, 16. Parvoline, 224, 308. Pat6 de foie gras, 118. Pathogenic bacteria in flesh, 279. Pathological ptomaines, 322. Pemmican, 104. Peptic digestion of proteids, 179. experiments, 86. peptones prepared by, 190. Peptones, action of dyes on, 143. action of formaldehyde on, 176, 199. characteristics of, 168. 332 INDEX. Peptones, composition of, 169, 181. compounds of, with hydrochloric acid, 160. estimation of, 173, 192, 195. flesh, analyses of, 199, 203, 205. flesh, prepared by papayotin, 190. flesh, prepared by pepsin, 190. flesh, prepared by superheated steam, 189. flesh, prepared by trypsin, 190. from gelatin, 159, 162. injection of, into the blood, 191. in meat extracts, 196, 201, 206. Kemmerich's, 189, 198, 203. Koch's, 189, 203. physiological value of, 190. precipitation of, by bromine, 168. precipitation of, by phospho- tungstic acid, 167. precipitation of, by uranium acetate, 173. Witte's, 205. See ' Anti-' and ' Hemi-pep- tones.' Perch, flesh of the, 65. Periodic law, precipitation of proteids in relation to, 165. Pheuyl-amido-propionic acid, 321. Phospho-carnic acid, 6, 82. Phosphomolybdic acid as a proteid precipitant, 174. Phosphorescent flesh, bacilli of, 273. occurrence of, 272. Phosphoric acid, determination of, 80. Phosphorus, in blood, 43. in fish, 21. in flesh, 22, 80. in oysters, 68. in lecithins, 21, 80. in nucleins, 21, 80. poisoning, efiect on flesh, 217. Phosphotungstic acid as a proteid precipitant, 167. method of preparing, 168. Physiological experiments in diges- tion, 87. Pickling fluid, composition of, 109. of flesh, 108. Picric acid, precipitation of proteids ,by, 174. Piestocystis in the crow, 244. Pig, composition of a, 49. Pigeon, fat of the, 63. flesh of the, 60, 61. Pigments in flesh, 6, 7, 70, 71. Pig's blood, hfemoglobin of, 144. Pig's fat, characteristics of, 55. constants of, 57. Pig's flesh, 21, 47, 55. See • Pork. ' Pike, flesh of the, 21, 65. Plasma, blood-, 40, 42. muscle-, 4, 5. Pleuro-pneumonia, flesh of animals infected wiih, 294. of cattle, micro-organisms of, 294. Poisonous canned meat, 116. fish, 219. flesh, 216. mussels, 221. sausages, 225. See ' Ptomaines.' Poisons, effect of, on flesh, 216. Polony sausages, 128. Pork, characteristics of, 54. composition of, 55. digestibility of, 55. food value of, 89. glycogen in, 138, 139. influence of pig's food on, 65. mineral constituents of, 21. sausages, 128. Potassium hydroxide, action of, on muscle, 134. Potted meats, composition of, 118. Pouchet's bases, 319. ptomaine extraction method, 298. Preservation of flesh, by antiseptics, 118. by cold, 102. by drying, 10^. by heat sterilisation, 112. by salting, 107. by smoking, 110. Primary proteoses, 165, 179. Pro-peptones, 155, 203. Propylamines, 109, 223, 301. Proteids, action of formaldehyde on, 175, 199. classification of, 150. coagulation of, 162, 163. colour reactions of, 160. compounds of, with hydrochloric acid, 160. decomposition by bacteria, 185. decomposition by papayotin, 186, 190. decomposition by pepsin, 179,190. decomposition by sulphuric acid, 176. decomposition by superheated steam, 177, 189. INDEX. 333 Proteids, decomposition by trypsin, 182, 190. optical rotation of, 163. precipitation of, by alcohol, 164, 199. precipitation by copper hydrox- ide, 170. precipitation by halogens, 168. precipitation by metallic salts, 165. precipitation by phosphotung- stic acid, 167. precipitation by ' saltingout,' 164. precipitation by tannin, 174. Protein-chromogen, 184. Proteolysis, products of, 181. Proteoses, characteristics of, 154. composition of, 149, 181. deutero-, 155, 156, 181. primary, 155, 181. Proto-albumoses, 156, 181. Protozoa, 227. Pseudo-xanthine, 14. Psorosperm saccules, 228. Ptomaines, classification of, 223. composition of, 223. extraction of, 298. flesh of animals poisoned by, 278. known also as leucomaines, 218. pathological, 322. separation of, 298. symptoms of poisoning by, 224. Purple flesh, 71. Putrefaction, bacteria of, 274. bacterial products of, 277. Eber's test for, 75. influence of, on animal parasites, 249, 263. ptomainesformed during the, 223. reactiono£fleshdaring,19, 74, 75. Putrescine, characteristics of, 303. physiological effects of, 224. separation of, 303. ' Putrid intoxication,' 278. Pyaemia, 279. Pyogenic bacteria in flesh, 279. Pyridine, 307. QuAKTER-EViL, baciUus of, 288. flesh of infected animals, 289. Quick-salting process, Eckart's, 107. Kabbit, bones of the, 31. coccideal disease of the, 229. fat of, 63. flesh of, 60. Rabbit, food value of. 89. mineral matter in flesh of, 21. Rabbit septicaemia, 281. Rabies, destruction of viras of, by heat, 213, 285. flesh of aniraalsiufected with, 285. virus of, 285. Ram, flesh of the, 33. Ray-fungus, muscle, 259, 296. Reaction to litmus, of blood, 33. of canned meat, 116. of caviar, 110. of muscle, 19, 75, 76. Red corpuscles of blood, 33. sausage, 125. Redness of flesh, abnormal, 71. Reichert value, determination of, 94. Rigor mortis, 4, 19, 209. Rinderpest, 294. flesh of infected animals, 295. ' Ripening ' of game, 62. Roasting of flesh, 208. Roe of fish, 18, 109. poisonous, 218, 220. Rontgen rays, trichinse detection by, 268. ' Roseline,' 72. Rose's method of separating fatty acids, 96. Rust, detection of blood in presence of, 44. Saffkon, coloration of flesh by, 71. Safranin, detection of, in sausages, 143. action of, on flesh proteids, 143. Salamiwurst, 126. Salicylic acid, detection of, 122. flesh preserved with, 76, 122. Salmon, canned, 113. colouring matter in flesh of, 7, 64, 117. cooked, 210, 211. digestibility of, 87. flesh of, 65. ova of, 117. Salmon, potted, 118. smoked, 111. Salt in meat extracts, 188. Salt fish, 108. Salt meat, 108. Salting, action of, on animal parasites, 263. action of, on bacteria, 108. influence of, on the flesh, 108. methods of, 107. 334 INDEX. Saponification value, determination of, 93. Sapraemia, 265, 278. Saprine, 223, 224, 306. Saprophytic bacteria, 274, 279. Sarcine, 14. Sarcolactic acid, 20, 103. Sarcolemma, 2, 3, 5. Sarooplasm, 4, 5. Sarcosine, 17. Sarcous elements, 4. Sardines, canned, 114. cooked, 210, 211. oil of, 66. red coloration of, 115. Saucisses, 128. Saucissons, 128. Sausages, acidity of, 133. American, trichiii* in, 264. analyses of, 127, 128. animal parasites in, 249, 263, 264. artificial coloration of, 142. bacteria in, 269, 272, 278. blood, 125, 127. composition of, 125, 128. cooking of, 262. English, 126, 128. examination of, 129-146. French, 128. German, 125, 127. gristle in, 133. horse flesh in, 133. liver, 125, 127. phosphorescent, 272. poisoning, 225, 278. preservatives in, 118, 122. specific gravity of, 130. starch in, 130. temperatures in cooking, 214. water in, 129. Sec 'Beef," Pork.' Saveloys, 128. Scarlet flesh, 71. Scherer's test for inosite, 20. Schjerning'sanalyses ofmeat extracts, 174, 205. proteids, separation method, 171. Schjerning's observations on the precipitation of proteids, 165. Schrotter's albumose, 157. Scombrine, 311. Scyllite, 21. Section cutting, 267. SepticEemia, flesh of animals infected with, 214, 220. Septicaemia, micro-organisms of, 280. See ' Rabbit.' Serum-albumin, 41, 149. Serum-globulin, 41. Serum of calfs blood, proteids in, 174. See 'Blood.' Sex, influence of, on the flesh of animals, 49, 51, 54, 77, 78. Shark oil, constants of, 66. Sheep, bones of, 31. composition of a, 49. cysticercus of, 242. fat of, 53. flesh of, 47, 51, 53. See 'Mutton.' Sheep-pox, 289. Shell-fish, bacteria in, 296. blood of, 45. digestibility of, 87. flesh of, 63. . mineral matter in flesh of, 21. Skate oil, constants of, 66. Smoked flesh, bacteria in, 270. composition of. 111. Smoking, action of, on animal parasites, 250, 263. action of, on bacteria, 110. influence of, on flesh. 111. methods of, 110. Snails, flesh of, 68. poisonous, 216. Sodium chloride, precipitation of proteids by, 165. Sodium salicylate, extraction of colour with, 145. Sole, flesh of, cooked, 210, 211. Somatose, 171, 189. Soup, 209. Specific gravity of connective tissue, 24. of blood, 33. of fat, 27. of sausages, 130. Spectra of haemoglobin and its derivatives, 39. Spirilla, 266, 276. Squirrel, haemoglobin crystals from the blood of, 35. Stag, fat of, 63. ' Staggers ' in sheep, 241. Staining tissues, methods of, 267. Stannous chloride, precipitation of proteids by, 170, 172, 205. Staphylococci, 212, 213,266, 270, 279. Starch, determination of, in sausages, 130. INDEX. 335 steam, action of superheated, on flesh, 177. action of, on proteids, 178. manufacture of peptones by, 189. Stearic acid, characteristics of, 27. determination of, 99. in animal fats, 26, 54, 56, 58. Stearin, 25, 27. Sterilisation of flesh, 112. public, 214. Stock-fish, dried, 107. Streptococci, 212, 266, 279. Striated muscular fibre, 1, 4. Stroma substance, 7. Sturgeon, roe of. See ' Caviar.' Sulphites, action of, on flesh, 76, 121. detection of, 121. Sulphur-compounds, Eber's test, 73. formed in 'heating' of game, 62. formed in ripening of game, 62. Sulphur in flesh, 21. determination of, 80. Sulphuric acid, action of, on proteids, 176. Twitohell's method of separating liquid fatty acids with, 99. Sulphurous acid as a flesh preserva- tive, 76, 120. Susotoxine, 282. Swine, cysticercus of, 235. Swine erysipelas, 73, 283. Swine fever, 281. See 'Pig 'and 'Pork.' Syntonin, 6, 150, 166, 168. absoiption of, in the system, 191. action of certain dyes on, 143. characteristics of, 152, 164. determination of, 169, 192. in meat extracts, 191, 192. T^NIA acanthotrias, 231, 238. ccennrus, 231, 240. crassiceps, 244. crassioollis, 241. cucumerina, 231, 244. echinococcus, 231, 242. flavo-punctata, 244. longicollis, 244. madagascariensis, 244. marginata, 231, 238. mediocanellata, 231, 232. nana, 244. perfoliata, 244. saginata, 231, 232. serrata, 231, 239. solium, 231, 234. Taenia tenella, 231, 241. Tseniadaj, 230, 244. and their related cysticerci, 231. thermal death points of, 248. Tallow. See'O-a: Tannin, Almeii's reagent, 174. precipitation of proteids hy, 83, 167, 174. Tapeworms, cystic, 232. hosts of, 231. ordinary, 244. See ' Tfenia ' and ' Tasniadse.' Tassajo, Carue, 104. Taurine, 18. Tetanus, bacillus of, 284. bacillus of, thermal death point, 212. flesh of infected animals, 285. virus of, influence of heat on, 213, 285. Thrombin or fibrin ferment, 41. Tin in canned meats, 116. Tin chloride, precipitation of pro- teids by, 170, 172, 205. Tongue, canned, 113. potted, 118. smoked, 111. toughness of, 78. Toughness of flesh, determination of, 77. Toxalbumoses, 191, 218. Toxigenes, 225. Toxines, bacterial, 213, 278. bacterial, action of heat on, 213, 226. in fish, 64, 221, 222. in flesh, 217, 218, 278. Trematoda, 251. Trichina spiralis, intestinal, 252. muscle, 254. Trichinae, bodies liable to be mistaken for, 258. detection of, in flesh, 258. influence of cold on, 261. Trichinae, influence of cooking on, 211, 262. influence of heat on, 262. influence of putrefaction on, 263. influence of salting on, 263. influence of smoking on, 263. inspection of meat for, 257. - 1 number of,in infected flesh, 257. position of, in flesh, 260. Trichinosis, occurrence of, 263. prevention of, 262. symptoms of, 256. 336 INDEX. Trichloracetic acid as a proteid pre- cipitant, 155. Triethylamine, 223, 301. Trimethylamine, 109, 223, 300. Trimethylenediamine, 302. Trout, digestibility of, 87. Trypsin, action of, on proteids, 1 82. digestion of gelatin by, 1 85. manufacture of peptones by, 190. Tryptic digestion, artificial, 86. Tryptone, 175. Tryptophan (pro tein-ehromogen),184. Tuberculin test, 292. Tuberculosis, Eber's test for, 74. flesh of infected animals, 213, 291. in cold-blooded animals, 294. occurrence of, 289, 293. symptoms of, 289. toiine of, action of heat on, 213. Tuberculosis, bacillus of, 289. action of gastric juice on, 290. influence of cooking on, 290. influence of putrefaction on, 291. influence of salting on, 290. influence of smoking on, 290. thermal death point of, 212, 290. Turbot, composition of, 210, 211. Turkey, bones of the, 31, 32. fat of the, 63. Tyrosamines, 224, 318. Tyrosine as a digestion product, 183. as a ptomaine, 321. characteristics of, 18. deposits in ham, 260. in flesh, 18. separation of, 184, Tyrotoxine or tyrotoxioon, 320. ' TJkAnium acetate, precipitation of proteids by, 159, 170, 171, 173. Urase, 151. Urine, extravasation of, into muscular tissue, 79. kreatinine in, 9. ptomaines in, 322. removal of peptones by, 191. Valentine's meat juice, 197. Van Ei-mengem's bacillus of sausage poisoning, 226, 278. Veal, characteristics of, 51. composition of, 47, 51. extractives from, 48. immature, 51. See 'Calf.; Venison, composition of, 60, 61. fat, constants of, 63. See ' Game.' Violet coloration of flesh, 71, 272. ' Vitalia ' meat juice, 197. Vitellins, 150, 162, 167. Water in flesh, 21. abnormal proportion of, 79. absorption of, by flesh, 142. determination of, 79. in meat extracte, 187, 193, 197. in sausages, 129. Weigert's method of staining, 267. White flesh, 70. White of egg, 148, 149, 162, 153, 169. Wild animals, fat of, 60, 63. flesh of, 60. Wild cat, fat of, 61. duck, fat of, 63. goose, fat of, 63. rabbit, fat of, 63. See 'Game.' Wildseuche, 281. Witte's peptone, 171, 174, 206. Wyeth's meat juice, 197. Wurste, 126, 127. Xanthio bases, 8, 11. tests for, 11. Xanthine, 15. See ' Hetero-,' 'Para-,' and ' Pseudo-xan thine.' Xantho-kreatinine, 10. Xantho-proteic reaction, 161. Xantosis, 71. Yellow flesh, 70. Yolk of egg, 18, 162. Zbin, 160. Zinc sulphate as a proteid precipitant, 164, 192, 198. PEIKTED BY MEILL AHD COMPANY, LIMITED, EDINBURGH. ' I