Columbia Umber£itj> mtfceCitpof J^etolfork College of ipijpstctans ano burgeons Reference Iltbrarp / •* fa Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/theorypracticeofOOchap The Theory and Practice OF INFANT FEEDING With Notes on Development HENRY DWIGHT CHAPIN, A.M., M.D. Professor of Diseases of Children at the New York Post-Graduate Medical School and Hospital ; Attending Physician to the Post-Graduate, Willard Parker and Riverside Hospitals ; Consulting Physician to the Randall's Island Hospital. WITH NUMEROUS ILLUSTRATIONS NEW YORK WILLIAM WOOD AND COMPANY MDCCCCII ft - Copyright, 1902, By WILLIAM WOOD AND COMPANY Co ntp FATHER AND MOTHER this volume is affectionately dedicated PREFACE. THE great and increasing importance the subject of artificial infant feeding is assuming in all classes of society has led the author to believe there might be a field for a work on this subject that, instead of laying down rules and formulas for preparing food supposed to be suitable for infants of different ages, aimed rather to show the fundamental principles of growth, nutrition, and digestion during infancy, and then leave it to the physician to apply these principles. The discovery that the law of conservation of energy applies to animal life has made the nutrition of adults almost an exact science. In infant feeding there are other problems than mere nutrition that must be considered. The great mass of literature on infant feeding that has appeared within the past few years has been devoted in the most part toward producing a substitute food that should chemically ap- proximate human milk. In this book the special func- tion of milk in developing the digestive tract of the young animal is treated, the author believes, for the first time, and it is more than likely that further study along this line may necessitate greater or less modification of the conclusions here drawn. vi PREFACE. American authorities on milk have been followed be- cause the conditions under which milk is produced and marketed in America are so different from those of Europe that many statements found in European medical jour- nals concerning milk supplies must be inapplicable to the work of a majority of American physicians, and besides, the greatest advances in dairying and knowledge of the chemistry of milk have been made in America. In the Appendix will be found a list of works and articles from which data have been drawn. The material of the book has been divided into four parts, each being as complete in itself as the subject will allow. By a system of cross references it is aimed to bring the prin- ciples involved and their application in close connection. The author wishes to acknowledge his indebtedness to Profs. W. A. Henry, S. M. Babcock, and F. W. Woll, and Major H. E. Alvord for valuable information; to Professor H. W. Conn for the chapter on Bacterio- logical Examination of Milk; to Dr. Hrdlika for making anthropological measurements, assisted by Dr. Pisek, and to Dr. Pisek for securing the photographs of infants. The thanks of the author are also extended to th,e pub- lishers for courtesies rendered during the preparation of the volume. Henry Dwight Chapin. 51 West Fifty-First Street, New York, August 1, 1902. CONTENTS. PART I. UNDERLYING PRINCIPLES OF NUTRITION. CHAPTER I. I'AGE General Introduction, . . . . . . . . . i CHAPTER II. How to Approach the Subject of Infant Feeding, .... 6 CHAPTER III. Animal Cell— Its Constituents— Growth a Process of Cell Division — Young Animal Rudiment of Parent, ...... 10 CHAPTER IV. Object and Processes of Digestion — Mechanism and Comparisons of Digestive Tracts, 16 CHAPTER V. Broad Classification of Food into Protein, Fat, Carbohydrates, Min- eral Matter, and Water, . . ... . . . . .25 CHAPTER VI. The Chemical Processes of Digestion — Comparative Digestion and Absorption in Different Animals, . . . . . 29 CHAPTER VII. Metabolism and Excretion, . ........ 36 CHAPTER VIII. Comparison of the Milk of Different Animals. Chemical and Physio- logical Differences, .......... 43 CHAPTER IX. Summary, . • . ' 54 viii CONTENTS. PART II. RAW FOOD MATERIALS. PAGE CHAPTER X. Cow's Milk, 59 CHAPTER XL Bacteriology of Milk, So CHAPTER XII. Preservation of Milk, .......... 94 CHAPTER XIII. Market Milk, 104 CHAPTER XIV. Methods of Testing Milk, 127 CHAPTER XV. Bacteriological Examination of Milk, ....... 140 CHAPTER XVI. Cereals, and Vegetable Foods, ........ 162 CHAPTER XVII. Proprietary Infant Foods, . . . . . . . . .171 CHAPTER XVIII. Meats and Eggs. 175 PART III. PRACTICAL FEEDING. CHAPTER XIX. Breast Feeding — Diet and Care of Mother — Elimination of Drugs in Milk — Care of Nipples — Contraindications — Menstruation — Preg- nancy — Wet-Nursing — Weaning and Mixed Feeding, . . . 1S7 CHAPTER XX. Methods of Selecting Food for Adults not Applicable to Infants— Nu- trition and Development of the Digestive Tract must be Consid- ered Together, 198 CHAPTER XXI. General Considerations in Preparing Infant's Food, .... 207 CONTENTS. ix PAGE CHAPTER XXII. Preparation of Food, .......... 227 CHAPTER XXIII. Selection and Administration of Food, 246 CHAPTER XXIV. Feeding by Gavage — Nasal Feeding — Rectal Feeding — Feeding Pre- mature Infants, .......... 258 CHAPTER XXV. Constipation, ............ 265 CHAPTER XXVI. Summer Diarrhoea, ........... 270 CHAPTER XXVII. Diet During Second Year, 279 PART IV. GROWTH AND DEVELOPMENT OF INFANTS. CHAPTER XXVIII. Growth and Development of Infants 287 CHAPTER XXIX. Methods and Results of Measuring Normal Infants, .... 300 CHAPTER XXX. Growth of Head, 308 References, 317 Index, 521 PART I. CHAPTER I. GENERAL INTRODUCTION. Two controlling factors are present in all life — hered- ity and environment. At the birth of the individual the first has done its best or worst and cannot be reckoned with in the sense of being influenced. Its activity has been through long reaches of past time, and the laws of its operation are but imperfectly understood. The ques- tion of environment, being of the present and to a certain extent possible of control, assumes the greatest impor- tance. While from a purely biologic standpoint heredity may appear to be the most important influence, yet in the scheme of evolution the higher the animal the more im- portant becomes environment. This is specially empha- sized in man by the prolongation of the period of infancy. John Fiske was the first to elaborate this fruitful view of one of the fundamental laws of higher evolution, that not only throws a strong light on the methods of evolution, but lays the greatest importance on the period of infancy as influencing the future development and usefulness of the animal. This long period of helpless infancy is a time of extreme plasticity, when the career of the individual is no longer predetermined by the career of its ancestor. One generation of the lower animals is almost an exact reproduction of the preceding one. The young animal is born pretty fully formed, and can look out for itself almost 2 INFANT FEEDING. from the beginning, independently of the parent. The longer the infancy of an animal becomes, the greater the period of its teachability, and a slow growth means an increase in capacity for development and all the higher prerogatives. Thus the higher apes have a helpless baby- hood, when for two or three months they are unable to feed themselves or move about independently of the pa- rent. The human infant is distinguished from the high- est of the lower animals by the very long duration of help- less infancy and the marked increase in the size of the brain, and particularly in the extent of its surface. There is here a great increase in the size and complexity of brain organization that takes place largely after birth. Accompanying the rapid growth of the nervous system is that of the skeleton and various visceral organs. Dur- ing the first two years of life the brain not only doubles in weight, but increases marvellously in its convolutions and complexity. The infinite distance between man and the lower animals consists in the fact that in the former natural selection confines itself principally to the surface of the brain, and requires a long period of helpless infancy for this highly plastic work to be properly started and developed. Inherited tendencies are there, but the proper environment counts for much in this work so potent in future possibilities. It is evident that, correlated with his long period of helpless infancy, there must be a time of maternal care and watchfulness, if the race is to exist in health and vigor. Knowledge is required as well as care, for mistakes made at this time can never be completely corrected. The first few years of life are, biologically speaking, the most important ones we live. The begin- GENERAL INTRODUCTION. 3 ning organism has at this time stamped on it the possi- bilities of future vigorous life or of early degeneration and decay. Hence a careful study and understanding of all the phases of infancy are of the greatest importance alike to physicians and parents. At a period of such rapid growth and development, it is evident that proper nutri- tion must play the leading part. All competent observers are agreed that the best nourishment for a baby naturally comes from its own mother. Unfortunately a large num- ber of mothers, from physical or social causes, are unable to give this proper nutriment. It appears to be one of the penalties of modern civilization that an increasing number of women cannot or will not nurse their offspring. Hence it is that in recent years a large amount of study and labor has been expended upon substitute infant feed- ing. Great advances have been made, but it must be confessed that the results are not always proportionate to the labor expended. The tendency appears to be to a greater degree of complexity and elaborateness than the average practitioner and mother can understand or ap- ply. Hence discouragement is apt to follow, and a return to old and haphazard methods if the immediate results are fairly satisfactory. Proprietary infant foods also pro- fit by this feeling of confusion, as they often agree with the baby for the time being, although not containing the proper ingredients for healthy growth and nutrition. The effort to place the food principles of milk in their proper ratio has led to "percentage feeding," which rep- resents a decided advance, but has been pushed to an extreme that is difficult, if not impossible, to apply. The author has long thought that some of the benefits of this 4 INFANT FEEDING. method of feeding come more from the care and cleanli- ness with which the milk is handled than from the minute changes in the percentages that are often advised; in- deed, analysis sometimes shows that these fine changes are more on paper than in the ingredients of the milk. It is well to think in percentages and be as exact as pos- sible in feeding a baby, but the problem has not thus been completely solved, when we are putting the milk of one species of animal into the stomach of another spe- cies having a different digestive apparatus. The greatest problem in the life of any animal is that of securing sufficient food. All forms of animal life de- mand the same ultimate food elements, so that really their great diversification is along the lines of methods and organs provided by nature for securing and digesting food. While the outward forms of animals are apparent to every casual observer, their digestive systems, which are hidden, are as much diversified as their more appar- ent shapes, and are as much adapted for the digestion of a particular food as the outward organs are for securing it. Hence the milk of each type of animal must be stud- ied from the standpoint of its special adaptation to the digestive tract for which it is intended : a hard curding milk is intended for a polygastric digestive tract that can properly deal with it ; a soft curding milk for a monogas- tric digestive tract. These differences assume the great- est importance when the milk of one species of animal is fed to another species. This subject will be carefully considered in the present work, as it has a direct practical bearing upon successful infant feeding. While percen- tage feeding and the physical differences in the same GENERAL INTRODUCTION. 5 ingredients in the milks of different species are of great importance, the preliminary question of how to get clean, fresh cow's milk is the fundamental one. Too little atten- tion has been given to this question in works on infant feeding. It will here be treated at some length and in detail, as the observations of the author lead him to be- lieve that future advances in infant feeding must be prin- cipally along this line. In order to insist upon pure, clean milk, the physician must know how it is produced and insist upon proper conditions. It can easily be produced anywhere, if the details are properly carried out ; and this does not require an elaborate, expensive plant, as many believe. It calls for knowledge on the part of the physi- cian or sanitarian that can easily be conveyed to the farmer and dairyman. This is the first requisite in successful infant feeding. CHAPTER II. HOW TO APPROACH THE SUBJECT OF INFANT FEEDING. i. Any one called on to feed an infant during the period it is normally nourished by its mother has a great respon- sibility thrust upon him and one not to be assumed lightly or without preparation. Too many are satisfied when something that is retained in the stomach and causes a gain in weight is found, no thought being given to whether the food contains material out of which healthy tissue can be formed. It has often been stated that an artificial food for in- fants should contain nothing that is not found in mother's milk, and that it should contain just what is found in mother's milk. To prove the suitability of various substi- tutes for mother's milk chemical analyses of both have been published, to show how closely the substitutes ap- proximate mother's milk. At first sight this seems a ra- tional procedure, but when it is remembered that there is no difference between a diamond and a piece of charcoal chemically , and that mixtures of butter, cheese, sugar, salts, and water, or of beef suet, raw beef, sugar, salts, and water, can be made which when analyzed by the usual methods will show the same composition as mother's milk, the fallacy of judging the suitability of a food for an infant, or for an adult for that matter, by its chemical HOW TO APPROACH INFANT FEEDING. 7 analysis only will be apparent. Physiological chemistry has not advanced sufficiently to make it a safe guide by itself. In feeding an adult it is only necessary to furnish enough food to repair waste. In feeding an infant not only must waste be repaired, but material to build up new tissue must be supplied, or the infant cannot grow nor- mally. The whole future of the infant may depend on what kind of food is supplied it up to the time it can take table food. Then the danger of an insufficient supply of tissue-building food is not so great. The ability to resist disease depends largely on having the cells in which the vital processes take place plentiful in number and well nourished. These cells form a large portion of all the organs and tissues of the body, and if the material needed to build cells is not furnished in suffi- cient quantity, the gain in weight, if there is any, will be mostly fat and water. It does not follow that because a baby is fat that it is strong or healthy. The cells may be actually starving and so few in number that the body may be likened to a large showy house built with very light timbers, all ready to collapse under a slight strain (128). Not only must the food for an infant contain material from which cells may be built up, but the material must be in such a condition that the infant can digest it with- out undue effort. Furthermore the food must be cheap enough to be within the reach of all and easily prepared. Naturally the milk of the cow or of some other animal is suggested, but experience shows that these milks do not agree with infants generally, unless in some way changed or modified, the great difficulty being the inabil- 8 INFANT FEEDING. ity of the infant to digest the elements of the milk of which cells are composed. Undoubtedly the milk of all animals contains the materials necessary to build up strong healthy cells and tissues, as no young animal thrives as well on anything else as it does on its mother's milk or on the milk of some other animal of the same species. At first thought it seems strange that the milk of one species of animal is not suitable for the young of another species ; but when the mode of living, and the digestive systems, rate of growth, and stage of develop- ment at birth of the different species are compared, it will be found that the milk of each animal is adapted to its own digestive system, rate of growth, and state of development ; also that the milk of the mother behaves in the young ani- mals stomach very much as the food of the mother behaves in her stomach. The young animal is being educated to digest in the same manner as it will when it is grown. This subject will be gone into in detail in subsequent chapters, as it has been given very little or no considera- tion by writers on infant dietetics. Before there can be intelligent food prescribing there must be a knowledge of the substances needed to con- struct cells and keep them well nourished ; of the sources from which these substances may be obtained; of how they are transmitted to the cells through the blood stream after digestion and absorption ; of the nature of digestion and the digestive systems of different animals ; of what changes take place in the food in the cells, and what be- comes of the waste products. Then only can feeding be taken up in a scientific manner. The problem of feeding infants in all classes of society HOW TO APPROACH INFANT FEEDING. 9 calls for ability to produce a satisfactory food in a simple and inexpensive manner. This necessitates a knowledge of raw food materials, how they are produced, and the best means of preserving them from deterioration and in- fection by disease or other kinds of germs, and how these food materials, no matter what their source, may be best prepared for digestion by the infant. Before taking up methods of preparing food for in- fants, some space will be devoted to physiological chem- istry, physiology of young animals, comparison of the digestive systems and milks of various animals, the produc- tion of milk and other raw food products, and methods of analyzing and testing food materials. CHAPTER III. ANIMAL CELL— ITS CONSTITUENTS— GROWTH A PROCESS OF CELL DIVISION— YOUNG ANIMAL RUDIMENT OF PARENT. 2. The unit of the animal organism is the cell. In the cells all the vital processes take place. They are the chemical laboratories of the body and are the ultimate destination of all the food that is digested. The starting-point in the growth of an animal is a sin- gle cell about one-one-hundred-and-twenty-fifth of an inch in diameter. This cell divides and forms an additional cell; these divide again, and so on. After a large number of cells have been thus formed, they arrange themselves into a membrane — the blastoderm — which consists of two distinct portions: (i) The archiblast, which consist of three layers — (a) the epiblast or outer layer, (5) the meso- blast or middle layer, and (c) the hypoblast or inner layer; and (2) the parablast, which fills up the spaces in the meso- blast or middle layer. As the process of cell division proceeds, the epiblast or outer layer develops into the skin and nervous system, the mesoblast or middle layer into the muscles, and the hypoblast into the lining of the respiratory, genito-uri- nary, and digestive systems ; while the parablast, which filled up the spaces in the mesoblast or middle layer, be- comes connective tissue, cartilage, bone, lymphatic ves- sels and tissues, blood cells, and blood-vessels. ANIMAL CELL. ii When the animal is able to maintain a separate exis- tence it is born, and to become an adult it has simply to enlarge and develop all the parts and add mineral matter Fig. i. — Section of Ovum. (Jewett.) Shows the original cell or starting-point of an animal. to the bones. This enlarging and developing of the body, or growing, is a simple extension of the process of cell ZONA PELLUCIDA POLAR GLOBULES Fig. 2.— Illustration of Cell Division or Growth. (Allen Thompson, after E. Van Beneden.) division. There can be no true growth without an in- crease of the number of cells, and no new cells can be formed except by the division of old cells. 12 INFANT FEEDING. The cells are so small that they cannot be examined except by the aid of a microscope, but as they make up a large part of the tissues of the body, a study of the tis- sues is practically a study of the cells. To the eye a piece of flesh consists of muscle, connec- tive tissue, cartilage, fat, and possibly mucous membrane, skin, blood-vessels, and nerves. The chief mass of these tissues, with the exception of water and fat, is called protein substance — the word pro- tein meaning "/ take the first place!' All protein sub- stance contains carbon, hydrogen, oxygen, and nitrogen. Mostoi it contains in addition sulphur, and portions con- tain also phosphorus and iron. While the quantities of these elements vary somewhat, they are fairly constant in all of the tissues, but a chemical analysis of protein would not tell whether it came from skin, mucous membrane, or muscle. Other means of examining tissues had to be devised. These consist of extracting the tissues with various solvents. By this process various forms of pro- tein can be separated to a certain extent. The principal groups of protein substances so separated are: (i) Albumins and globulins, containing carbon, hy- drogen, oxygen, nitrogen, and sulphur. (2) Nucleo-albumins, containing carbon, hydrogen, nitrogen, oxygen, sulphur, and also phosphorus and iron. There are many forms of protein that are included in these divisions; for instance: White of egg is a mixture of albumin and globulin. Casein of milk (curd) is a nucleo-albumin. Another class of substances which contain carbon^ hydrogen, oxygen, and nitrogen, but which are not protein ANIMAL CELL. 13 substances, can be separated from animal tissues. These are called extractives or meat bases. The extracts of meat for making beef teas, sold in jars, which are claimed to represent ten to twenty times their weight "of meat, are "extractives " (no). Fat, which is composed of carbon, hydrogen, and oxy- gen only ; lecithin, a kind of fat which contains also phos- phorus and nitrogen, found particularly in the brain and nerves; and glycogen or animal starch, composed of car- bon, hydrogen, and oxygen, but in proportions different from those in fat, can also be separated from animal tissues. Mineral substances found in the tissues are thought to be combined with the protein substances and not to exist in a free state. 3. In examining cells under a microscope, it is found that a certain portion of each cell — the nucleus — contains iron and phosphorus, and that the albumins and globulins which do not contain iron and phosphorus serve more as cell food than as cell builders. Lecithin and glycogen seem to be found in all cells. There can be no cell division or growth unless the nucleus of the cell first divides, and, as iron and phospho- rus are contituents of the nuclei of cells, there can be no cell growth unless food containing iron and phospho- rus is furnished. This has been proved by experiment. The materials necessary to build up cells must be found in eggs, as in an egg there is a single cell that be- gins to divide and ends by changing the contents of the shell into a live bird. The germinal cell is situated near the yolk, which is used up first, and then the white is drawn on. The yolk is rich in protein containing phos- i 4 INFANT FEEDING. phoms and iron, lecithin, fat, and mineral matter; while the white of the egg, which is about eighty-five per cent water, contains almost nothing that could be used to cre- ate cells (2). 4. Up to the time an animal is born it is nourished by the blood stream of its mother, so all the elements for the developing animal must come originally from the moth- er's food. It would be expected that animals that feed on flesh, as cats and dogs, would be able to supply the materials needed to construct animal tissue ; but animals that feed exclusively on vegetable substances, as cows, sheep, and horses, also have no difficulty in constructing animal tissue. In fact, most of the meat supply of the world is the flesh of animals that live exclusively on vege- table substances, so the only conclusion is that the vege- table kingdom must be able to supply all the materials necessary to form animal tissue. Examination of hay, wheat, oats, barley, corn, beans, etc.. shows them to consist principally of carbohydrates which contain only carbon, hydrogen, and oxygen. Cel- lulose, or the skeleton of plants, starch, and sugar are typical carbohydrates. Paper is made of the cellulose or cells of wood or straw. Potatoes and cereals contain large quantities of starch, and beets, sugar cane, and maple trees supply sugars. Starch and sugar are the stored-up food of plants. Vegetable tissues contain also small quantities of fat and lecithin and substances containing carbon, hydrogen, oxygen, nitrogen, and also sulphur, phosphorus, and iron, called vegetable protein. It is these substances that are converted into animal cells. Gluten or the sticky, stringy part of bread dough is a familiar ANIMAL CELL. 15 form of vegetable protein. Chemically there is little dif- ference between gluten and lean meat. There is one important fact to be remembered : plants have the ability to take water, mineral matter and gases from the soil and air and combine them into proteid, fat, and carbohydrates. Animals cannot do this nor can they change fat and carbohydrates into proteid, but must take these three substances from the vegetable kingdom and elaborate them for their own particular uses; so a perfect food must contain proteid, fat, and carbohydrates in proportions suitable to the needs of each particular animal. It is evident that a cat or dog would starve if fed hay and grass, and that a horse or cow would not as a rule thrive on raw meat. Human beings feed on meat and vegetable substances, but not in the condition in which the lower animals eat them. They must be prepared by a cooking process before the human digestive apparatus can act to advantage. This forces the conclusion that the digestive system of each kind of animal must be particu- larly suited to its natural food. As young animals are miniatures or rudiments of their parents, their digestive systems must be in a general way like those of their pa- rents, so it would be natural to suppose the mother's milk would be particularly suited to the young animal's diges- tion, and that the milk of one kind of animal would not suit the young of another kind any more than the food of a cat would suit a cow or a horse. It is the substitution of some other milk that causes so much trouble in infant feeding. Chemistry has never been able to show why this substitution causes trouble. The answer has been hinted at, — different digestive systems. In the following chapters this important subject will be treated. CHAPTER IV. OBJECT AND PROCESSES OF DIGESTION- MECHANISM AND COMPARISONS OF DI- GESTIVE TRACTS. 5- The object of digestion is to separate from the food that is eaten those portions that will serve as nutriment to the organism from those that are useless, and to put them into soluble, absorbable forms, so that the blood can carry them to every part of the body. The process of digestion consists of two distinct parts: (i) a mechanical part, and (2) a chemical part. The me- chanical part consists of grasping, tearing, chewing, or grinding the food ; the chemical part in the solvent action of the various digestive juices. The chemical changes that take place in a particular kind of food during digestion are practically the same in all forms of animal life, but the mechanism of digestive tracts varies greatly, and the kind of digestive juices that are secreted depends largely on the natural food of the animal. All animals must have protein in some form and all have digestive juices that will digest it, while some animals have in addition digestive juices that will digest many other substances. A dog whose principal food is animal protein (meat) does not need a digestive juice that will soften hay or grass, and does not have it. A horse or cow needs a digestive juice that will soften and digest OBJECT AND PROCESSES OF DIGESTION. 17 the fibres of hay or grass and liberate the vegetable protein they contain, when the same chemical change in the pro- tein takes place as in the dog's digestion. The discussion of what are the chemical changes that take place during digestion will be deferred until the mechanism of digestion has been briefly considered. 6. To furnish a dog a pound of protein, about four pounds of lean meat would be fed, meat being about three-fourths water; to supply a horse a pound of protein, about thirty pounds of grass or sixteen pounds of dry hay would have to be fed. It is apparent that not only must the digestive system of a horse be relatively much larger than that of a dog, but much more complicated. It is a well-established fact that the more complicated the food the more complicated is the digestive tract. When a jelly fish comes in contact with its food it folds itself around it. When all the nutriment has been extracted it unfolds again. In a higher form of life the digestive cavity is permanent and is a straight tube. As- cending in the animal scale, the digestive tract becomes longer, curved, and separated into distinct parts that have special functions. Organs for grasping the food are pro- vided, and the character of the food and the digestive sys- tem of the animal can often, if not always, be known by a glance at these structures. - Animals of prey have teeth adapted for tearing flesh and crushing bones. Their gullets are distensible, and they can swallow great pieces of meat and bones. Their digestive juices are particularly adapted for dissolving meat and even bone, and their digestive apparatus is short and simple. Their stomachs are capacious, being sixty INFANT FEEDING. to eighty per cent of the whole digestive tract, and the outlet to the intestine is small and kept closed until the food is liquefied, thus insuring thorough gastric digestion. Herbivorous animals, like the cow, goat, sheep, horse, and ass, have teeth for thoroughly chewing their food, and their gullets are small and non-distensible. With the cow, goat, and sheep, the food is first swallowed without chew- ing, and goes into the paunch or rumen, where it is softened very much as is the food in a bird's crop. The animal lies down and at its leisure ruminates or rechews the food, which then goes into the fourth stomach — these animals have four stom- achs — where it is princi- pally digested, and then passes into the intestines through a small outlet, which allows only liquid or semi-liquid food to pass out. The stomach of the cow, goat, and sheep comprises about seventy per cent of the digestive tract. The horse and ass, which eat the same kind of food as the cow, have entirely different digestive systems. They Fig. 3. — Simple Digestive Tract of Carnivor- ous Animal (Dog). Stomach sixty to eighty percent (After Bernard, modified.) OBJECT AND PROCESSES OF DIGESTION. 19 chew their food once for all. Their stomachs comprise only eight to nine per cent of the digestive tract, and will Fig. 4.— Complicated Digestive Tract of Ox or Cow. Stomach seventy per cent. (Chauveau.) (1) Stomach. (2) Intestines. not hold more than one-third to one-half of a meal. The outlet to the intestine is large and open, and while the 20 INFANT FEEDING. animal eats a meal the food passes directly into the intes- tine, which at the farther end is enormously developed, forming about sixty per cent of the entire digestive tract. Young birds of prey are fed flesh, young worm-eating birds are supplied with worms, and young seed-eating birds with seeds. Here it is plain that the digestive sys- -Interior of Ox's or Cow's Stomach. (Chauveau.) terns of young birds are very much the same as those of the parents. All young animals that are suckled are furnished milk, which is a fluid, while the parents' food is solid. This seems to be different than in the case of young birds which receive solid food, but in the stomachs of these young animals is found rennet, a substance that changes milk into a solid or semi-solid condition. Jun- ket is a familiar example of cow's milk turned into a solid. OBJECT AND PROCESSES ' OF DIGESTION. 21 It has been stated that rennet seems to be a superfluous substance in the stomach, seeing that the milk is again Fig. 6.— Complicated Digestive Tract of Horse. (Y) Stomach, eight to nine per cent. (2) Intestines, ninety-one to ninety-two per cent. (Chauveau) converted into a fluid by the digestive process, but that this is not so will be seen presently. 22 INFANT FEEDING. While chemical analyses show all milks to be alike in containing the same ingredients, but in different propor- tions, milks differ in their behavior with rennet, and as chemical analyses give so little information as to the char- acter of the milk, chemists classify milks according to their behavior with rennet. It is found that cow's, goat's, and sheep's milk form solid curds when acted upon by rennet, which even when broken up into fine particles will readily unite again; while horse's and ass' milk form a fluid jelly which will not become solid. Human milk seems to stand between these two types of milk. The greater part of the digestion of cows, goats, and sheep is performed in their stomachs, which, as stated be- fore, comprise about seventy per cent of their whole diges- tive system. In changing the milk of these animals into a solid that cannot easily leave the stomach, the rennet causes the digestion of the young animal to take place in its stomach, the same as in the case of the parent. The stomach of the horse or ass, being only eight or nine per cent of the digestive tract, will not hold enough food for a meal, and the outlet to the intestine is large, so the food can easily leave the stomach, which it does con- tinuously during a meal. The milk of the horse or ass does not form a solid lump, but a fluid jelly that can read- ily be forced into the intestine, which comprises ninety per cent of the digestive tract. Here again it is plain that the mother's milk is exactly suited physically to the digestive tract of the young animal, and that the process of digestion of the young animal is similar to that of the parent. In human beings, which eat meat and vegetable sub- OBJECT AND PROCESSES OF DIGESTION. 23 stances, the digestive system is adapted for either class of food, but the food must be prepared for digestion by- thorough chewing of meat and by cooking of vegetable substances, as no paunch or enlarged intestine is fur- nished where they may lie and soak preparatory to diges- tion. The human stomach, which comprises about twenty per cent of the digestive tract, is provided with a small outlet to prevent lumps passing into the intestine. This small outlet, teeth for dividing every kind of food, and salivary glands that secrete more fluid than the kidneys, show that the stomach was intended to receive soft, finely divided material which could easily pass into the intestine. If any proof of this conclusion was needed, the distress that is often brought on by hasty eat- ing and bolting great lumps of food would furnish it. Human milk does not form a solid lump or fluid jelly in the stomach, but a soft, finely divided mass. A whole book could be written showing instances of how nature adapts an animal to its surroundings and food, but from the few instances cited, which bear particularly on the feeding of young animals, it will be clear that, in Fig. 7. — Human Digestive Tract. Stomach, twenty per cent. (Leidy.) 24 IXFAXT FEEDING. physical properties at least, there are different kinds of milk and that these differences are not freaks of nature or inexplicable, but are of the highest importance in de- veloping the young animal's digestive system ; also that milks are not interchangeable from a digestive standpoint. These physiological comparisons throw a strong side light on the difficulties necessarily met with in utilizing the natural food of one species for the nutriment of another. In a future chapter the composition of milk will be dis- cussed and an attempt will be made to show that the dif- ference in composition of the milk of various animals is closely connected with the natural development and growth of the young animals. Before this subject is taken up, a little space will be devoted to the chemistry of food and digestion. CHAPTER V. BROAD CLASSIFICATION OF FOOD INTO PRO- TEIN, FAT, CARBOHYDRATES, MINERAL MATTER, AND WATER. 7. Food is generally divided into four great classes: I. Protein, often called proteid or albuminoids. II. Fat. III. Carbohydrates. IV. Mineral matter or salts. In addition to these, water is a very important ingredient of food, as it enters into the composition of every part of the body, the bones even being over ten per cent water. There are many other important ingredients of food, but they are not gen- erally considered, as they are usually found with one of these four classes. The function of the protein of food is to build up muscular tissue; fats and carbohydrates are heat-producers, and mineral matter hardens the bones. I. Protein. The exact composition of protein or pro- teid has never been discovered, but it has been found that the different forms consist of: Carbon 50. 6 -54. 5 per cent. Hydrogen 6. 5 - 7-3 Nitrogen (average about 16 per cent. ) 15.0 -17.6 Sulphur o. 3 - 2.2 Phosphorus o. 42- o. 85 Oxygen 21.5 -23. 5 Iron is also found in some forms of protein. These figures in a general way represent the composi- tion of lean beef, pork, mutton, veal, fowl, fish, and of 26 INFANT FEEDING. the total proteid of milk and eggs. Vegetable proteids seem to have about the same composition and chemical properties as animal proteids (4). II. Fatsaxe entirely different from proteids in compo- sition, being composed of about: Carbon 76. 5 per cent. Hydrogen 12.0 " Oxygen n. 5 " III. Carbohydrates form the chief portion of the dry substance of the vegetable kingdom. The principal carbohydrates that are the natural food of animals are starch, found in potatoes and in nearly all the grains, and cellulose or the framework of plants. For human food, starch, in the form of cereals and bread ; glucose, found in grapes, raisins, molasses, and syr- up ; cane siigar, or the familiar granulated sugar, which is found in sugar cane, beets, carrots, and the maple tree ; and milk sugar, found in milk, are the principal carbohy- drates used. All these are composed of carbon, hydro- gen, and oxygen, there being two parts of hydrogen for each part of oxygen, which is the proportion in which these elements combine to form water, FLO. Hence the carbon is hydrated, and the name carbohydrates. Cellulose consists of CeHioOo or C 6 (H 2 0)5 Starch " " C 6 Hio0 5 Glucose " " CeHjoOs Cane sugar " " C12H22O11 Milk sugar " " C12H22O11 Chemically the only difference between all these car- bohydrates is the quantity of water (H 2 0) combined with the carbon. Physically there are great differences. Milk sugar and cane sugar, which have the same composition, BROAD CLASSIFICATION OF FOOD. 27 are different from each other, as also are cellulose and starch. IV. Mineral matter is found in all forms of food, but it is hard to tell much about the state or combination in which it exists. 8. In comparing the composition of proteids, fats, and carbohydrates, it will be noticed that the proteids are very complex and contain a fairly constant percentage of nitro- gen, which is not found at all in the fats and carbohy- drates. As proteid takes such a variety of forms, the only practical method of determining it quantitatively is to determine the quantity of nitrogen in the food and consider it sixteen per cent of the total proteid, as all pro- teid contains about sixteen per cent of nitrogen. The weight of proteid is found by multiplying the weight of the nitrogen by 6.25 (16 per cent X 6.25 = 100). It is not pretended that this method is exact, but it is the best that can be devised and answers all practical pur- poses. The lecithin, which is a kind of fat, is included with the proteid, as it contains nitrogen. Fats are determined by extracting the food with ether or other fat solvents. Carbohydrates cannot be determined directly. It is customary in most food analyses to determine proteid, fat, water, and mineral matter, add their weights together, and call the remainder carbohydrates. Mineral matter is determined by burning some of the food and weighing the ash. 9- It is easy to see that a mere chemical analysis is not a safe guide in selecting a food for an animal, for a dog could not, on account of its simple digestive system, get 28 INFANT FEEDING. at the protein or fat of whole corn, for instance. It would starve with a stomach full of food that would nourish if it could only digest it ; after the corn was ground and cooked, the dog could digest it. This has led to a physi- ological test to see how much of a certain kind of food each species of animal can digest and assimilate. A meal is weighed, and the fat, proteid, carbohydrates, and mine- ral matter are determined. The animal is then given a capsule of lampblack and a little later is fed the meal ; be- fore the next meal another capsule of lampblack is given. The discharges from the bowels are collected, and what is between the two lampblack marks contains what was left undigested from the meal. This excrement is ana- lyzed and the digestibility of the meal determined. By this method some old theories of feeding have been completely upset, for it had been assumed that many foods were just what was needed because chemical analy- ses showed them to contain large quantities of nutri- tious substances. Digestion tests, however, showed that they were not digested, and so of course there was no ad- vantage in using the foods. A great many of these tests have been made on farm animals, and the following analy- sis will give an idea of the results : Water. Ash. Protein. hydrates. Per cent. Per cent. Per cent Per cent. 61.6 2.1 3-1 32.OO 6l.6 ? 2.28 23.71 13.2 4-4 5-9 74.OO 13.2 ? 2.89 43-72 II. O 3-0 11. 8 69.2 II. O ? 9- 2 5 48-34 87.2 0.7 3-6 4-9 87.2 3.4S 4-7 Fat. Per cent. Timothy grass contained " digestible ' ' hay " " digestible Oats contained " digestible Cow's milk contained " digestible . . 1.20 • 77 2-5 1-43 5-0 4.18 3-7 3-7 CHAPTER VI. THE CHEMICAL PROCESSES OF DIGESTION- COMPARATIVE DIGESTION AND ABSORP- TION IN DIFFERENT ANIMALS. io. Before any food that is eaten can be of use to the organism it must be chemically changed so that it can pass into the blood in suitable form. Each animal is fur- nished with digestive juices that produce the requisite changes in its natural food, but just what these changes are or how they take place is not thoroughly understood. The kind of digestive juice that is secreted depends largely on the food that is eaten. In the lower forms of animal life, as the jelly fish, which folds itself around its food, it is found that if animal food is taken, a digestive juice that will digest meat is secreted ; if vegetable food is taken, a digestive juice that will digest vegetable sub- stances is secreted. As it was shown (6) that the more complex the food of an animal is, the more complex is its di- gestive system, so it will be found that the more complex the digestive system, the greater number of digestive juices there are secreted, each distinct portion of the di- gestive tract having a peculiar digestive juice particularly adapted to the condition of the food when it reaches it. In animals that live on flesh, a strong juice that dis- solves meat and even bone is found in the stomach. The food does not need to be chewed or moistened before 30 INFANT FEEDING. swallowing, and consequently little saliva is secreted. Here digestion is simple and the digestive tract is corre- spondingly simple (see Fig. 3). When it comes to herbivorous animals, like the cow, goat, and sheep, the digestive system becomes exceed- ingly complex (see Fig. 4). When hay is eaten it must be softened, and the ox secretes ten to twelve gallons of saliva a day; when grass is eaten, only one-third as much saliva is secreted. The food of these three animals goes to the paunch or rumen and soaks until the cellulose (crude paper) that envelops the nutritious portions of the food is softened and partly digested when the food is re- gurgitated and rechewed, and then passes into the true stomach where digestion principally takes place. In birds with crops and gizzards practically the same process is ob- served. The goat's fondness for bill posters and labels is not altogether the result of degeneration. It can digest part of the paper and all the flour paste on it. With the horse, mule, and ass, which eat the same kind of food as the cow, goat, and sheep, the order in which the digestive juices act is different. Their food is chewed with the saliva before it is swallowed, and the ex- posed portions that are easily digested are dissolved and the remainder of the food is passed into the caecum at the far end of the intestine (see Fig. 6), which holds as much as a cow's paunch, where the cellulose is partly dissolved, allowing the enclosed nutriment to be then digested. With cows, etc., digestion takes place principally at the beginning of the digestive tract ; with the horse and ass, at the end of it. It might be truthfully said that the great difference in CHEMICAL PROCESSES OF DIGESTION. 31 the food of animals (for all must have protein, fat, carbo- hydrates, and mineral matter) lies in the fact that the food of herbivorous animals is wrapped up in cellulose (paper), while the food of carnivorous animals and human beings is not enclosed in cellulose. After this wrapping is re- moved from the food there is very little difference in the ability of different species of animals to produce the nec- essary chemical changes in the same food. Nature is very elastic on the food question, and in selecting a diet it is not so necessary to pay attention to fine points as to whether the food contains all the necessary elements and to their physical condition. Human beings cannot take their animal food in huge pieces as do carnivorous ani- mals, nor their vegetable food in the form herbivorous animals find convenient. Meat must be chewed and veg- etable substances cooked to break open the envelopes of cellulose. Each little starch grain has a coat of cellulose on it, upon which the human digestive juices have little action. Cooking starch by boiling or baking, as in bread, breaks these coats open and then the starch is readily digested (103, 105). 11. The chemical changes in the food are brought about by enzymes found in the digestive juices. These en- zymes have never been isolated in a pure state, and what they are is not known. Their presence can be detected only by their action on food. There seems to be a par- ticular kind of enzyme for each kind of food. In human saliva is found ptyalin (diastase), which con- verts cooked starch into dextrin and maltose. In the gas- tric juice is found pepsin, which is secreted along with hydrochloric acid, which converts proteid into albumoses 32 INFANT FEEDING. and peptones. Gastric juice has a strong solvent action on the connective materials that bind the muscular fibres together and causes meat to swell up and disintegrate into fine particles. The greater part of human digestion is performed in the intestine, so the action of the saliva in digesting the exposed starch and the action of the gastric juice in disin- tegrating the connective material of meat and vegetable proteids are preparatory to intestinal digestion and must be important. Fat, sugar, and starch are not acted upon by the gas- tric juice, and when present in excessive quantities in- terfere with its secretion. Fat and starch, by coating proteids, prevent the action of the gastric juice and throw the work of the stomach on to the intestines. Soaking bread in tea or coffee or washing down food with water does away with the action of the saliva on the starches, and filing food coats it with fat so that neither the saliva nor gastric juice can well act on it. Pork, on account of its containing so much fat, is particularly indigestible. In the intestine are found enzymes that will convert proteids into albumoses and peptones, but intestinal di- gestive juice does not cause proteid to swell up and disin- tegrate first, as does the gastric juice ; starch that escaped the action of the saliva is converted into dextrin, maltose, and dextrose ; cane sugar into dextrose and levulose ; and milk sugar into dextrose and galactose. As far as chem- istry shows, all these changes consist of the chemical ad- dition of water to the original proteid or carbohydrate. The actual changes have never been discovered. There are also found in the intestine enzymes that split and CHEMICAL PROCESSES OF DIGESTION. 33 emulsify fats. Some of these enzymes are secreted by the pancreas, and others by glands of the intestines. These enzymes seem to act by contact, and to act best, the food must be finely divided and pulpy. Their diges- tive power is enormous. One part of crude invertase digested one hundred thousand times its weight of cane sugar, and was still active. 12. The process of human digestion differs from that of the lower animals, in that the vegetable food must be pre- pared outside of the body to rupture the cellulose envel- opes, and the animal food chewed. The food then is to be first treated with a starch-digesting fluid, the saliva, to expose the proteid ; next with the gastric juice which dis- integrates proteid and reduces it to a pulpy jelly, and then only will the pylorus naturally open to allow food to pass into the intestine, where the greater part of the chemical changes in the food take place previous to ab- sorption. 13. The secretion of the digestive juices is under the control of the nervous system. The thought of an appetiz- ing meal makes the mouth water, and the food is then pretty apt to be digested. Pleasant-tasting food taken into the mouth also excites the secretion of the digestive juices. The absorption of certain substances from the diges- tive tract strongly excites the secretion of all the digestive juices. Among the substances that act as promoters of digestive secretion are the products of salivary digestion of starch (dextrin and maltose), and the extractives of meat (2). Substances which have the power of stimulating digestive secretion are also found in milk. 34 INFANT FEEDING. 14. The process of digestion is laborious at the best, one-sixth of the entire force of the organism being required to digest an average meal ; so an indigestible meal that re- quires prolonged digestive secretion, or has to be digested in the intestine without preparation in the mouth and stomach, causes great weariness. Excessive quantities of fat in the stomach retard not only the digestion of proteid by coating it, but also retard the secretion of the gastric juice and cause loss of appe- tite. Excessive quantities of sugar cause the stomach to secrete an unusually acid gastric juice, which interferes with digestion. These two facts should be remembered, as they have great practical value in infant feeding. Nervous shock or excitement interferes with normal digestive secretion. 15. Just how much of each of the digestive juices is secreted is not known, but an adult secretes more saliva than urine. There seems to be a continuous flow of di- gestive juice and absorption of digested food during the process of digestion. The process of absorption of pro- teid is not known. Some change takes place in the di- gested proteids during their passage through the walls of the digestive tract into the blood, for the products of pro- teid digestion are not found in the blood, and if injected into the blood are eliminated unchanged by the kidneys. Fats are emulsified and absorbed with little change. 16. After the digested food has passed from the diges- tive tract into the blood, it must be carried to the cells in every part of the body. This does not take place sud- denly but gradually. Those portions of the digested food that are not immediately required are stored up for future CHEMICAL PROCESSES OF DIGESTION. 35 use. The excess of carbohydrates is stored away in the muscles and liver in the form of glycogen, which is simi- lar in composition to starch ; a great excess of carbohy- drates is eliminated by the kidneys or converted into fat. Excess of fat is stored away as fat. Proteids are not stored up in the adult, any excess being excreted, as will be explained in the next chapter. i7- When an animal is not fed at all, the processes of life continue for a certain time, but there is a steady loss of weight. The glycogen stored in the liver disappears almost completely ; the stored-up fat also disappears, and all the muscles shrink away, and at last the animal dies. For a long time it was not known how the tissues fed upon themselves, but it has been recently discovered that in the blood there are enzymes that will digest glycogen or animal starch, converting it into dextrin, maltose, and dextrose, which is then carried to the portions of the body where it is most needed and again converted into glycogen. This is found to be the case even in the foe- tus. This same process must take place with fats and proteids, but the enzymes that produce the changes or what is the nature of the changes in the proteids have not been discovered. These enzymes that act in the system are called en- zymes of translocation, and have somewhat different modes of action from those of the digestive enzymes. They have been better studied in the vegetable kingdom, and their action can readily be appreciated by watching a potato sprout in a dark cellar or in the changing of a sprouting pea or a bean into root, stem, and a pair of leaves. CHAPTER VII. METABOLISM AND EXCRETION. 18. The process by which the digested food is built up into living tissue, and the living tissue and food are re- duced to other and simpler dead forms, is called metabolism. This process is going on continually in the organism ; the object of food is to replace the loss caused by destructive metabolism and to build up new tissue. There can be no scientific feeding without a knowledge of the functions of each kind of food, how it is changed in the organism, what are its by-products, and how they are excreted. 19. Fats and carbohydrates composed of carbon, hy- drogen, and oxygen are completely burned in the body by the inhaled oxygen of the air, into carbon dioxide and water, which are excreted principally through the lungs. These two food principles are mostly used 2&fuel\.o sup- ply the necessary heat to keep the body warm and fur- nish living force. Proteids can also act as fuel, but are incompletely burned in the body. The carbon dioxide produced in the metabolism of proteid is thrown off by the lungs, but the distinctive by-products of proteid metabolism are carried off by the urine in the form of urea, uric acid, phosphates, sulphates, and other salts; so a study of the urine is very important. 20. In practice, to determine the quantity of proteid METABOLISM AND EXCRETION. 37 that is being actually consumed in the body, it is only nec- essary to determine the quantity of nitrogen in the urine and multiply by 6.25 (8), which gives the weight of the pro- teid. It is a singular fact that in an adult animal there is what is called a nitrogenous equilibrium — that is, the amount of nitrogen eliminated equals the amount taken in as food. If the fats and carbohydrates are fed in ex- cess of the requirements of the body, they are generally stored up as fats, but with proteids it is different; an increase of proteid in the food produces an increase in the quantity of nitrogen in the urine, and in a few days the quantity of nitrogen excreted equals the quantity taken in as food. Possibly the excess of proteid is not all wasted, it may be partly changed into fat, but the only way an increase of proteid in the body can be brought about in an adult is by muscular activity, which increases the size of the muscles. Inactivity increases fat. Activity decreases fat and increases proteid up to a certain point. Growing animals that are laying on proteid are full of activity and playful, which they cease to be, as a rule, when fully grown. 21. The amount of nitrogen that is eliminated in the urine depends on the animal's food ; the urine of carnivor- ous animals is rich in nitrogen, while the urine of herbivor- ous animals is poor in nitrogen, which shows that in the flesh-eating animals large quantities of proteid are being consumed as fuel, while in the vegetable-eating animals, whose food is principally carbohydrates, small quantities of proteid are thus consumed. 22. When animals are starved they immediately com- mence to live on their own flesh and become carnivorous. 38 INFANT FEEDING. Experiments made with metabolism during starvation show that the urine of the herbivorous animals becomes the same as that of the carnivorous animals in every way. The stock of carbohydrates (glycogen) that is stored up in the liver of all animals disappears after a few hours of starvation, and then the fat and proteids begin to disap- pear. During starvation the temperature of the animal re- mains about the same as in health, and the amount of ni- trogen in the urine, while less in quantity, is the same in proportion to the weight of the animal as it was in health in the case of carnivorous animals, and greatly in excess of the quantity in health in the case of herbivorous ani- mals whose diet is principally carbohydrates. Hence herbivorous animals do not stand starvation so well as the carnivorae. Metabolism is very active in young animals. Children die of starvation after about four or five days, while adults can often starve twenty days without lasting injury. Just before death from starvation the quantity of ni- trogen in the urine increases greatly; then the tempera- ture drops below normal, and the animal dies — the fire has gone out. Upon examination of the animal it is found that all the fat of the body has disappeared, even the bones having lost, and the proteid has been drawn on until the muscles of the heart are too weak to act. The increase of nitrogen in the urine just before death marked the time when all the fat had been used up and the proteid had to be drawn on exclusively for fuel. 23. If a starving animal is fed carbohydrates or fats the quantity of nitrogen eliminated in the urine is greatly re- METABOLISM AND EXCRETION. 39 duced and the animal loses weight less rapidly, but event- ually dies, as these food elements cannot be converted into proteid and there is always a certain consumption of proteid. Fats and carbohydrates are proteid sparers, car- bohydrates being more effective than fats. The knowl- edge of how to take advantage of this fact is of great value in the treatment of diarrhoea and fevers in which there is increased destruction of proteid with decreased elimination of urine, and in kidney affections in which the urea cannot be eliminated normally. 24. If a healthy carnivorous animal is fed albumin (white of egg), which is a form of protein, it will die from starvation in about two months. Death from starvation will also follow if fats and carbohydrates are fed along with albumin, fibrin, or gelatin, which are all forms of protein. Attempts at separating different forms of protein for food purposes are not to be recommended, as grave errors in nutrition are likely to be the result. This much is known: the protein found in meat, whole milk, grass, and cereals, when given in the original state without attempts at separation into distinct classes or forms, will support life and produce good healthy tissue ; but just what part each form of protein plays in nutrition is not known. The form of fat and carbohydrate can be changed with little or no ill effect, but to assume if a form of food which contains sixteen per cent nitrogen and is digestible is given for protein that perfect nutrition will follow, is a policy that may lead to anaemia, rickets, or other forms of malnutrition. 25. It will be seen from the foregoing that the functions of the fat and carbohydrates of the food are principally to 4 o INFANT FEEDING. supply heat and living force, and those of the proteid to build the growing- tissue and to repair waste ; also that when the waste in the tissue has been made good from the food, the excess of proteid in the food is burned and eliminated and not stored up as proteid in the adult. From a fuel standpoint, fat, carbohydrate, and proteids are interchangeable in about these proportions: fat, 2}{ ; proteid, i ; carbohydrate, i ; but from a tissue-building standpoint they are not. This knowledge has led to the use in animal feeding of what is called a balanced diet ; that is, a diet which contains enough digestible fat and carbo- hydrates to furnish heat, and enough proteid to prevent a loss of proteid tissue. This point is determined by find- ing whether the nitrogen in the proteid of the food equals the nitrogen in the urine. The amount of proteid re- quired in the food depends largely on the animal. Wool- producing animals, as the sheep and goat, need more pro- teid than is actually used in the vital process in order to form the wool and hair; and milk-producing animals need more proteid in the food than those of the same species that are not secreting milk, as from three to four per cent of the milk is proteid. In an adult animal it is a waste to give much more nitrogen (proteid) in the food than is found in the urine during a period of fasting under the same conditions of living, as the only result is to throw extra work on the digestive and excretory systems with no gain to the organism. With children and young animals there should be more nitrogen (proteid) in the food than is found in the urine, as they need it to pro- duce new growth of tissue, and true growth consists of increasing the quantity of proteid in the body. METABOLISM AND EXCRETION. 41 26. In artificial infant feeding the great difficulty lies in supplying proteid suitable to the infant's needs and diges- tion, and the great temptation is to cut it down in quantity or supply it in forms that are very easily digested. The result is that either not enough proteid to produce much healthy growth is furnished, or a large quantity of a form of proteid that cannot do more than retard the infant's consumption of its own tissue is given, and a poorly devel- oped child is often the result. This is an error that is almost sure to result from a diet based simply on a chem- ical analysis. 27. During the process of digestion there is a greatly increased destructive metabolism of carbohydrates, fully fifteen per cent greater than in fasting under the same conditions, and also a slight increase in the destructive metabolism of proteid. Examination of the glands secret- ing the digestive juices shows that they absorb lymph, which is in some way changed into digestive juice and then secreted. Here is a source of slight loss of proteid during digestion, for this proteid matter is not all ab- sorbed, but goes in part to make up fecal matter. It is supposed by many that the faeces consist of undigested food. This is true to but a slight extent. Fecal matter consists almost wholly of secretions from the digestive tract. The intestines of a new-born infant contain fecal matter — meconium. A starving animal produces fecal matter similar to meconium, and a perfectly clean loop of the intestine will secrete feces. The character and quantity of the fecal matter de- pend largely on the food that is eaten. On an exclusive meat diet it is scanty, black, and pitch-like, and quite sim- 42 INFANT FEEDING ilar to that from a starving animal, which is living on its own tissues. When fat is added to the food the fecal matter contains fat and is lighter in color, When vege- table substances are added to the diet the quantity of fae- ces increases and the color changes with the character of the food. The increased quantity consists in part of un- digested food, but principally of the increased secretions of the mucous membrane of the intestine, caused by the coarseness of the food and the mechanical action of the undigested portions. In health the color of the fecal matter depends on the kind of food. Bile pigments, calomel, and senna produce a green color, iron and bismuth a black, and rhubarb a yellow color. In normal digestion of human beings there should be little undigested food in the fecal matter, so an examina- tion of the stools is of the greatest importance in feeding infants — in fact, is absolutely essential to success (156). CHAPTER VIII. COMPARISON OF THE MILK OF DIFFERENT ANIMALS. CHEMICAL AND PHYSIOLOGI- CAL DIFFERENCES. 28. The milk of all animals must contain the materials necessary for the nourishment of their young. Chemical examination of milks shows them all to agree in contain- ing water, fat, proteids or albuminoids, carbohydrates, and mineral matter. In addition to these ingredients, lecithin, cholesterin, citric acid, and other substances are found in varying proportions. The present knowledge of the chemical composition of milk can be best appreciated by the following quota- tions from recent high authorities upon the chemistry of milk: " Our present knowledge of the albuminoids of milk is far from complete, though much work has been done on the subject. This is due to the fact that it is extremely difficult to obtain these compounds in anything like a state of purity. . . . As there is no means of knowing when all the impurities have been eliminated, it is possible that we are yet unacquainted with the albuminoids of milk in a state of purity. This should not be forgotten during the study of the milk albuminoids. " In the albuminoids, the milks of different animals differ greatly. They may be divided broadly into two 44 INFANT FEEDING. classes — those which give a curd on the addition of an acid, and those which do not. In the first class are in- cluded the milk yielded by the cow, the goat, the gamoose, etc.; and in the second, human milk, that of the mare and the ass may be cited as examples. In the first class the curd is composed of casein, which is combined with phosphates of the alkaline earths; while in the second this is replaced by a similar albuminoid, which is not, however, combined with phosphates. It is possible that the difference between the albuminoids of the two classes is simply dependent on the presence or absence of the phosphates; but the chemistry of these bodies is only in its infancy, and it would be premature to offer an opinion at the present time. Besides casein, or a similar body, there exists in all milks a second albuminoid called albumin ; this differs from casein by not being precipitated by acid, and by being coagulated by heat. Other albu- minoids have been described in milk, but many of them are only decomposition products of casein or albumin, which were formed during the process adopted for the removal of the other albuminoids. . . . ' The sugar in milk is of a peculiar nature; that of cow's milk is called "lactose," or, more commonly, sugar of milk. It is generally assumed that all milks contain the same sugar, but of this there is some doubt. . . . " The sugar of the milk of the mare has the property of easily undergoing alcoholic fermentation, a property not possessed by lactose. According to the experiments of Carter and the author, the sugar of human milk is not identical with that of the milk of the cow" (Richmond). " The nitrogenous constituents of milk are very un- MILK OF DIFFERENT ANIMALS. 45 stable compounds and their study presents many and great difficulties; as a result we find that no two scientists who have made a special study of these compounds agree as to their properties, aside from those of casein and albumin, or their relation to the nitrogenous substances found else- where in the animal body " . . . (Farrington and Woll). " The milk fat has rather variable specific gravity, which according to Bohr is 0.949-0.996 at -+- 15 C. The milk fat, which is obtained under the name of butter, consists in great part of the neutral fats palmitin, olein, and stearin. Besides these it contains, as triglycerides, myristic acid, small quantities of butyric acid and cafij'oic acid, traces of caprylic acid, capric acid, lauric acid, and arachidic acids. . . . Milk fat also contains a small quan- tity of lecithin and cholesterin, also a yellow coloring matter. . . . " The milk plasma, or that fluid in which the fat globules are suspended, contains several albuminous bodies, casein, lactoglobulin, and lactalbumin, and a little opalisin, and two carbohydrates, of which only one, the milk sugar, is of great importance. The milk plasma also contains extractive bodies, traces of urea, creatin, crea- tinine hypoxanthin (?), lecithin, cholesterin, citric acid (Soxhlet and Henkel), and lastly also mineral bodies and gases" (Hammarsten on cow's milk). It will be readily seen that an analysis of milk that took into consideration all its minor ingredients would be an exceedingly complex process and to a certain extent a needless one ; as a matter of fact there has never been a process of complete analysis of milk worked out. The usual method of analysis is to evaporate a speci- 46 INFANT FEEDING. men of milk to dryness and call its weight total solids. What ether will extract from " total solids " is called fat, although the lecithin is also included. The total nitrogen in the milk is determined and its weight multiplied by 6.25 (8) and called pi'oteid. In this proteid is again included the lecithin as it contains a little nitrogen. A portion of the total solids is burned and the weight of the ash in the milk is calculated as mineral matter. The weights of water, fat, proteid and mineral matter are added together and subtracted from the weight of the milk and the differ- ence called carbohydrates or sugar. This method is not exact, but answers all practical purposes in ordinary methods of calculating food values. Methods of determining casein and albumin in milk consist of adding acid which precipitates the casein but not the albumin ; the casein is removed by filtration and the filtrate is boiled, which precipitates albumin; the nitrogen in each is determined and multiplied by 6.25, When the weights of the casein and albumin so deter- mined are added together there is not as much total pro- teid as when the nitrogen in the whole milk is determined and multiplied by 6.25. According to A. Winter Blyth, an English authority on food, the casein of woman's, mare's, and ass' milk sep- arates only with great difficulty, and then not completely, upon the addition of acids. This may and probably does account for the small quantity of casein reported in wom- an's milk by some chemists and the larger quantity ob- tained by others who employed different methods of analysis. This subiect will be alluded to in another place (145). MILK OF DIFFERENT ANIMALS. 47 No method of quantitatively determining the sugar in milk has been devised. It is either determined "by dif- ference," or rotation of a ray of polarized light, or by the reduction of alkaline copper solution. The quantity of sugar present in a specimen of milk varies slightly with the method of determining it. 29. The composition of any kind of milk varies a great deal and it is customary to speak of average milk. The composition of average milk is determined by adding together a great many analyses of milk and dividing the sum by the number of analyses. It may be that the re- sulting composition of milk may have never been actually met with. In speaking of woman's milk Hammarsten says: " Even after those differences are eliminated which depend on the imperfect analytical methods employed, the quantitative co7nposiiion of woman's milk is variable to such an extent that it is impossible to give any average results " ; and of the milk of other animals, — " To illustrate the composition of the milk of other animals the follow- ing figures, the compilation of Koenig, are given. As the milk of each kind of animal may have a variable com- position, these figures should be considered only as ex- amples of the composition of milk of various kinds:" Milk of the— Water. Solids. Proteids. Fat. Sugar. Salts. Dog 75-44 81.63 86.91 83.50 87.17 90.06 90.00 24.56 18.37 I3.O9 16.50 12.83 9-94 10.00 9.9I 9.08 3.69 5-74 3-55 1.89 2.10 9-57 3-33 4.09 6.14 3-69 1.09 1.30 3-^9 4.91 4-45 3-96 4.88 6.65 6.30 O 71 Cat 5S 86 Goat Sheep 66 Cow 7i 31 Ass 30 From the analytical figures just given it might readily be inferred that the great difference between milk of all 48 INFANT FEEDING. animals lay in the different percentages of water, proteids, fat, sugar, and salts, but a glance at the following analyses of cheeses made from milk with which all are familiar will show what a grave error such a conclusion would be if applied to cheese : Water. Proteids. Ordinary cheese (made of cow's milk) . . Roquefort cheese (made of sheep's milk) 27.20 26.50 32.05 52.30 36.60 32.90 4.15 4.4 30. Chemists have recognized that for anything but comparison of potential food values, analyses of milk are valueless, and have classified milks according to their curding properties. All milks contain at least two forms of protein: casein, or, as it is called by some writers, caseinogen, and albumin, while some milks contain a large proportion of other forms of protein. Casein of cow's milk is easily precipitated by cold dilute acids, while albumin is not. The curds of sour milk consist principally of precipitated casein, If an alkali is added to neutralize the acidity of sour milk the casein assumes its original form. However, the precipi- tation, or curding of milk, by the addition of acids is not the physiological curding of milk. In the stomach of animals is found an enzyme — rennet — which clots milk very much as blood is clotted, and the character of this clot depends on the kind of milk that is used. 31. The clotting of milk by rennet is an entirely differ- ent process from the precipitating of casein by acids or the souring of milk. Cow's milk is changed by rennet into a solid, which shrinks into a leathery, stringy mass that MILK OF DIFFERENT ANIMALS. 49 contains the fat of the milk embedded in the meshes of the curd. The albumin and other protein bodies and the sugar of the milk are squeezed out as " whey." Horse's and ass' milk form a very soft, gelatinous curd with ren- net, and woman's milk forms finely divided curds. Even after the milks are classified according to their curding properties there are great differences in the com- position of the milks which need to be explained. Now, if instead of making the chemical analyses or curding properties of the milks the bases of comparison, the milks are classified according to the natural order of the animals producing them, the reason for the wide differences in milks will appear, and each milk will be seen to be specially adapted in composition and curding properties to the rate of growth and digestive system of the young animal it was intended to nourish (Chapter IV.). Types of milk. 'S Curds. a V -c a 'a) ^ ? U a. Attains puberty in months. Carnivorous Dog. Sheep Goat. Cow. Mare. Ass. ? 75-44 83.50 86.91 87.17 90.06 90.00 88.20 9-57 6.14 4.09 3-69 1.09 1.30 3-30 3-19 3-96 4-45 4.88 6.65 6.30 6.80 9.91 5-74 3- 6 9 3-55 1.89 2. 10 1.50 0-73 .66 % ■31 •30 .20 6-8 (Stomach 60 to So per cent of digestive tract.) Ruminant } (Stomach 70 per cent of digestive tract.) (Intestine 90 per cent of digestive tract.) Human Solid Solid Solid Gelatinous Gelatinous Flocculent 6-8 6-8 S-12 iS iS Myrs. (Stomach 20 per cent of digestive tract.) It should be remembered that these milks vary some- what in composition. (See 32 A, for separate analysis of proteids.) 5 o INFANT FEEDING. It will be noticed that the milk of carnivorous animals is exceedingly rich in proteids ; that the milk of herbivor- ous animals, whose digestion is principally gastric, forms •solid curds which cannot easily leave the stomach ; that the milk of herbivorous animals, whose digestion is prin- cipally intestinal, forms gelatinous curds which easily leave the stomach and pass into the intestine; and that woman's milk, which was intended for a digestive system in which the gastric digestion is more than that of the horse or ass, but not so great as that of the cow or goat, curds in flakes which stand between the other two types of curds. ' It is also remarkable how close to each other in type of composition the milks of different animals of the same class appear to be, and what a close relation there is be- tween the composition of the milk and the rate of growth of the animal. It may be pointed out that the fat and proteid in ewe's milk are much greater in quantity than in goat's milk and greater in goat's milk than in cow's milk. At first sight there appears to be no reason for this, but there is. Sheep produce wool and goats produce hair which are made up of protein substance and fat. Over forty per cent of the weight of raw wool is of a fatty nature and this fat is found not in the wool fibre alone but mostly on it. It is the familiar lanolin or wool fat. Hair does not have much fat on it and goat's milk does not contain anything like the same quantity of fat as sheep's milk. There is an apparent discrepancy between the com- position of cow's milk and mare's milk and the rate of development of their young. It must be remembered MILK OF DIFFERENT ANIMALS. 51 that cows have been bred for years for the purpose of producing milk, and those animals that did not produce rich milk have been rejected. The ordinary common stock of cows does not produce milk containing fat 3.69, proteids 3.55 per cent, as shown in the analysis, but nearer fat three per cent and proteids three per cent. The dairy laws in most of the States call for only three per cent of fat in milk. Horses and asses have not been bred so as to produce rich milk as have cows. When these facts are taken into consideration, the apparent discrepancy dis- appears. 32. One of the great differences between woman's milk and other milks, which is well known, but which is not shown in the analyses, is that woman's milk is richer in lecithin, which forms a large part of the brain and nerves. Within half an hour after birth a calf, lamb, kid, or colt can stand, and in a day or two runs around and sees, hears, and smells about as well as its mother. In other words, it is born with a fully developed nervous system. A baby is very different in this respect, and it needs material for building up its nervous system, and this is found abun- dantly in woman's milk, but not so much in other milks. 32 A. In all milks there is greater or less quantity of soluble proteid generally called albumin, although not nearly all albumin, which is not retained in the curd, but which separates with the carbohydrates in the whey (31). This soluble proteid is readily absorbed from the digestive tract. It was shown that during digestion there was a slight increase in proteid and a large increase in carbohydrate metabolism (27). The first step in the digestion of milk, it 52 INFANT FEEDING. will be seen, is a separation of easily absorbed proteid and carbohydrate, for which there is a great demand during digestion, from the casein and fat, which require more digestion and which are stored away in the growing ani- mal as fat and muscle; and in another place it will be shown that the fat of milk is mostly secreted at the latter part of a suckling or milking (36). 32 B. The quantity and character of the soluble proteids of milk are of considerable interest in the comparison of milks. In 1897 Babcock and Russell discovered enzymes in milk which would digest its proteids in time if the bacteria present were destroyed by means other than heat, which destroyed the enzymes. To prove that the changes in the proteids of the milk were due to these enzymes, some very carefully conducted experiments and analyses were made. The casein and albumin were removed from milk by heating with acetic acid and filtering. The character of the remaining nitrogenous compounds was then carefully investigated, and they were considered to be principally albumoses and peptones (11). The milks were set aside, and from time to time portions were analyzed to detect the rapidity of the digestive process which was found to be slow, months being required before it was half completed. While the discovery of the presence of these enzymes in milk has no practical significance in infant feeding the analyses made in this connection are of the greatest value. In the following analyses by Babcock, Russell and Vivian only the cow's and goat's milk were the mixed secretion of several animals. In another place (38) will MILK OF DIFFERENT ANIMALS. 53 be found many complete analyses of the proteids of cow's milk. Date. December 4th, 1897. December 4th, 1897. December 4th, 1897. December 4th, 1897. December 29th, 1897. December 13th, 1897. February 1st, 1898. . March 8th, 1898 May 2d, 1898 June 23d, 1898 July 1st, 1898 February 21st, 1898. April 20th, 1898 April 28th, 1898 December 29th, 1898 February 21st, 1898. March 8th, 1898 Kind of milk. Sheep Sheep Sheep Sheep Sheep Human 1 ? . . uman | = g . . Human ! 3 «. . . Human j § * Human | 3 ■£ .,. Human J 7 ■ ■ Goat Pig Pig Mare Burro Half-bred buffalo Cow 3 u Sol. N. Per cent. 0. 76 0.09 •71 . IO .60 .IO .76 .09 .80 . IO .28 . IO .28 .10 > .27 . 10 .27 .09 .28 .10 .27 . 10 .78 .06 •72 • 17 .70 .16 .28 .09 •25 .10 .48 .04 •51 .04 y r X6.25 = (by author) r_ "a H ■c c 4-75 4 43 3 75 4 75 5 00 1 75 \ 1 75 1 68 1 68 1 75 1 68 4 87 4 5i 4 37 1 75 1 54 3 00 I 3 18 r- 1> 0) a a ...,... 20. 27 Magnesia ■ ... 2.80 Potash 28. 71 Soda 6.67 Phosphoric acid 29. 33 Chlorine , 14. 00 Carbonic acid .97 Sulphuric acid , Trace. Ferric oxide, etc , , , . . .40 103.15 Less + CI , 3.15 100.00 " Lecithin found dissolved in the fat, citric acid, urea, and cholesterin are minor constituents of cow's milk. Certain enzymes are also found in milk, but these have practically no importance except in the manufacture of various kinds of cheese. These enzymes are mentioned in another place (32). 36. Composition of Cow's Milk. — The composition of cow's milk varies greatly, and it is impossible to give a rep- resentative analysis that will do more than show what the average composition of milk would be during a long period if the cows gave the same milk each day and at each milking. This kind of analysis is useful only in showing the amount of food material cows produce during a stated period. One Cow's Milk. — The milk of individual cows shows great and sudden variations in composition, and it is for this reason that the mixed milk of a herd of cows is better for general use than one cow's milk. While there are great differences in composition between the mixed milks of different herds of cows, there are not apt to be great 62 INFANT FEEDING. and sudden variations, and with care the milk can be kept very uniform in composition. The changes in composition in one cow's milk are caused by various influences, as sudden change of the character of the food, fright, unfamiliar surroundings, and irregular intervals between milkings. Gradual change in the character of the food, running from low proteid to high proteid and vice versa, low fat to high fat and vice versa, and high carbohydrates and low proteids cause no perceptible change in the composition of the milk. It is the opinion of all investigators that the quantity and quality of the milk depend on the cow, and that there is no method of feeding that will cause a particular cow to change the natural quality and quantity of milk secreted, except for a few days, when there will be a return to the normal of each cow. The following analyses of individual cow's milk show: (i) The variation in quantity of fat and size of fat globules in different portions of a milking — the solids not fat seem to change little; C 2 ) the variations in composition and yield of milk during a lactation period ; and (3) the effect of irregular hours of milking. These analyses are suggestive of changes and conditions affecting the secre- tion and composition of breast milk. (1) Fractional Milkings. Boussingault (quoted by Richmond) reports : First portion. Per cent. Second portion. Per cent. Third portion. Per cent. Fourth portion. Per cent. Fifth portion. Per cent. Sixth portion. Per cent. IO.47 I. 70 3-77 IO.75 I.76 S.99 IO.85 2.IO S.75 II.23 2-54 8.69 II.63 3-14 8.49 12.67 4.08 Fat 8-59 COW'S MILK. 63 Collier at the New York (Geneva) Experiment Station obtained the following figures: First Cow — First Second Third Fourth Fifth Sixth Seventh Eighth Ninth Tenth Eleventh Twelfth Thirteenth pint Fat. Per cent. 0.3 • -3 • -4 • -7 •7 . 1. 12 1.7 2.2 2.55 • 3-0 • 3-35 • 3-9 4-95 All mixed 1 . 9 Second Cow — First pint Second " Third " Fourth " Fifth «« Sixth 4 * Seventh " Eighth " , Ninth " Tenth *• , All mixed 2.77 Third Cow — First pint Second " Third Fourth Fifth Sixth Seventh Eighth Ninth Tenth Eleventh Relative size fat globules. 36 44 93 10S 97 133 154 174 114 147 190 194 251 129 0.5 123 1. 1 204 i-3 178 1.8 137 2.4 342 3-4 221 4-45 340 5-o 347 5.o 270 6.25 365 218 1.55 337 3-05 367 3-30 338 4.00 476 4.40 323 5- 00 575 6. 10 565 6.50 833 7.00 722 8.05 725 9.40 644 All mixed 6.00 659 6 4 INFANT FEEDING. (2) Variations in composition and yield during a lac- tation period, reported by Farrington. Holstein Cow — 278 Samples. Daily yield in pounds. Highest 37-0 Lowest 1.7 Average 21.7 Solids not fats — per cent. Highest 10.9 Lowest 7- 2 8 times below S.o 24 " above 9.0 Short Horn Cow— 428 Samples— Sudden Changes not Common. Fat — per cent. Highest 6.6 Lowest ... 1.5 72 times below 3.0 25 " above 4. 5 Proteids — per cent. Highest 4. 11 Lowest 2.64 Daily yield in pounds — Highest 26. 5 Lowest 3.5 Average 14- 4 Solids not fat — per cent. Highest 11. 3 Lowest 7. 2 1 1 times below 8.5 7 " above 10. 5 Jersey Cow — 614 Samples — Sudden Changes Common. Fat — per cent. Highest 7.9 Lowest 2.5 17 times below 3.0 3S " above 4.5 Proteids — per cent. Highest 3.89 Lowest 2.92 Fat — per cent. Highest 12.3 Lowest 2.9 5 times below. 3.5 25 " above 7.0 Proteids — per cent. Highest 5.3 Lowest 2.98 Daily yield in pounds — Highest 25.5 Lowest 1.0 Average 16. 4 Solids not fat — per cent. Highest. II. 7 Lowest 7.6 3 times below S.o 24 " above to. 5 (3) Unequal Intervals between Milkings. The shorter the intervals between milkings the smaller will be the yield and the richer the milk. Long intervals cause large quantities of poor milk. It is for this reason that gener- ally in summer, morning milk is richer than night milk, and in winter, night milk is richer than morning milk. COW'S MILK. 65 Cows are milked the first thing in the morning and the last thing at night by most farmers. In summer the nights are about nine hours long, and in winter the days have about this same length. The following tests made at the Delaware Experiment Station illustrate these statements. Yield. Ounces. Fat. Per cent. Total solids. Per cent. Milking at 7 a.m 154.6 151. 1S4.O 112. 5 4.63 4-74 4-3 6 5-32 14-25 14-37 14.53 I5-36 " " 8 A. M " 5 p-m Night milk. Fat — per cent. Morning milk. Fat — per cent. July 24th , 3-76 4 sfi 4-67 February 5th 37. Curdijig of Milk. — The curding of sour milk, so fa- miliar to every one, consists of a precipitation of the casein by the lactic acid developed during the souring process. Upon neutralizing the acid with an alkali the casein goes back into its original condition. The curding of milk in the stomach is an entirely different process (6, 31). It is brought about by the action of rennet, which clots the ca- sein very much as blood is clotted by the enzyme thrombase which exists in the blood. The milk forms a solid jelly when acted on by rennet, which soon begins to contract, and a greenish-yellow fluid known as whey exudes, which contains a small amount of fat, the soluble proteids, the sugars, and part of the mineral matter of the milk. A slightly acid condition of the milk greatly favors the curd- ing or clotting of milk by rennet. When the conditions are right the curd shrinks rapidly and forms a tough, semi- fibrous mass that contains the fat in its meshes. If this 5 66 INFANT FEEDING. curd is broken into small particles they readily unite again into a solid mass if allowed to remain in contact with each other; but if the particles are agitated for a few moments a skin or membrane forms on each, which prevents their uniting. The casein in this form of curd is changed chemically and cannot be put back into its original form by any known process. It is often stated that cow's milk has an acid reaction when it leaves the cow or in its fresh state. Acidity of milk is never estimated directly, but by the use of some color indicator. Milk that is neutral to litmus is usually quite acid to phenolphthalein; but it is thought that this is not true acidity, but the effect of the salts found in the milk. The acidity of milk that aids the action of rennet is true acidity and is shown by litmus. An interesting proof that the acidity to phenolphthalein is not true acid- ity has been shown by Babcock, Russell, Vivian, and Hastings. They found that pepsin, which digests proteid only in the presence of acid, would not attack the proteids of milk that was acid to phenolphthalein until 0.2 per cent. HC1 was added, also that the boiled milk would not coagulate with rennet ; but it did so at once, as soon as acidified. It is important that the difference between the acid curds and rennet curds of milk should be understood. Much confusion has arisen because this difference was not considered. Series of tests with acid curds have been used as bases for preparing cow's milk for infant feeding, but, as under physiological or rennet curding, entirely dif- ferent results are obtained, these teachings, based on acid curding of milk, have been abandoned. COW'S MILK. 67 A clear conception of the difference between the acid curding (precipitation of casein) and the rennet curding (clotting of cow's milk) can be quickly obtained by per- forming the. following experiments, preferably in small evaporating dishes: 1 st. Dissolve 1 c.c. of hydrochloric acid in 99 c.c. of water. Add this gradually to 60 c.c. of fresh milk that is neutral or only faintly acid to litmus paper until a pre- cipitate forms, and note how many cubic centimetres of the dilute acid were required to precipitate the casein. This is the sour-milk curd. 2d. To 60 c.c. of the same .milk add first 1 or 2 c.c. of a solution of rennet made from the commercial liquid rennet or from the junket tablets sold in all grocery stores —one tablet to 30 c.c. water — and then add the dilute hydrochloric acid until a precipitate forms, and note how many cubic centimetres of the dilute acid were required to cause the precipitate to form. Much less acid will be required than when no rennet is used. Now bring the curded milk to blood heat and the rennet curd will begin to shrink and after a few minutes will become tough and fibrous so that it can be handled without breaking. If this experiment is performed, using 20 c.c. of milk and 40 c.c. of water, the shrinking is more pronounced. With a little practice, milk diluted ten times with water can be curded with rennet so that all of the curd will unite into one small piece. Without the addition of the dilute acid the curding process takes more time. If the casein is first precipitated by the acid the rennet will not cause it to clot. Occasionally specimens of milk will be met that do not readily form a curd with rennet. 68 INFANT FEEDING. 38. Mixed Milks and Whey. — Market milk is a mixture of the secretion of many cows, and varies between three and five per cent of fat ; but the milk of any particular milkman is quite uniform from day to day. It is useless then to think of average milk, so a number of complete analyses of milks within the normal range will be given. In many of the older analyses of milk the total proteids are called casein ; in other analyses the total proteids and the casein have been determined, and the difference be- tween these has been called albumin. In some more re- cent analyses the proteids other than casein have been determined, but there is as yet no generally accepted method of separating these proteids. As the relation between the quantity of casein and so- called albumin of milk has been made the basis of a system of infant feeding, some space will be given to this subject. It has been pretty generally believed and accepted, on the authority of Koenig and Blyth, that there is a quite constant ratio between casein and albumin of cow's milk, there being about five times as much casein as albumin. Van Slyke, in looking over a large number of analyses of normal milks reported by different analysts, found that the ratio between casein and albumin in these analyses was as high as ten parts of casein to one of albumin, and as low as three parts of casein to one of albumin. He then began a systematic examination of milk to deter- mine the ratio between casein and albumin, if there was one. This test, which is remarkable, extended over a pe- riod of several years ; and during the first year the milk of fifteen hundred cows in four counties of New York State was used at several cheese factories. The total quantity COW'S MILK. 69 of milk used was 214,684 pounds, and 106 analyses were made in triplicate to exclude any chance of error. His' conclusions then were: "Our results show that the rela- tion of albumin to casein is a very variable one instead of constant, and in no single instance did any sample of the mixed normal milk contain as much as five parts of casein for one of albumin, the highest being 4.9, while the aver- age was 3.76 parts casein for one of albumin." In the following analyses of Van Slyke, the casein and albumin (total proteids), and casein were determined direct- ly, and the water, albumin, sugar, and ash indirectly. These analyses were made in triplicate both for the milk and the whey, and are exceedingly useful in showing the range of composition of mixed milks that may be met anywhere, and the composition of whey made from a particular milk. Milk . Whey. Milk Whey. Milk . Whey Milk . Whey Milk . Whey- Milk . Whey Milk Whey Milk Whey Milk- Whey a. 88.40 93-13 87.81 92.60 87.97 92.83 87.94 92.82 S7-52 9 2 -93 87.52 93.02 87.80 93-27 87-45 93-Q4 87.38 93-05 II.OO 6.87 I2.I9 7.40 12.03 7-17 12.06 7.18 12.48 7.07 12.48 6.98 12. 20 6-73 12.55 6.96 12.62 6-95 ffl.S C - 5 u 2.64 .69 2.72 .71 2.63 3.20 .88 3-14 .Si 3-09 S- 1 5 .83 3-15 .86 98 0. 06 . 03 # 97 •43 ■47 •5i • 44 •47 X c n f - -~ / a; v p 0-0 c v 5 £ 22 ,66 .66 .60 .6S 77 .67 5S 7i .68 5-9i 5.90 6-37 6.36. 6.10 6. 10 6.06 6. 12 5-8 3 5- 96 5-84 5-79 5-56 5-52 5.80 5.81 5-82 5-79 INFANT FEEDING. Milk , Whey Milk, Whey Milk Whey Milk Whey Milk Whey Milk Whey Milk- Whey Milk Whey Milk- Whey Milk Whey Milk Whey Milk Whey. Milk Whey. Milk- Whey. Milk Whey, Milk- Whey. Milk Whey. Milk- Whey. Milk Whey. Milk Whey. a u 0— ° a. 87.46 93-17 12.54 6.83 87.41 93.18 12.59 6.82 87.54 93- 19 12.46 6.81 S7-34 93.16 12.66 6.84 87.41 93-23 12.59 6.77 87.29 • 93- 10 12.71 6.90 S7.00 93.04 13.00 6.96 86. 91 93-17 13.09 6.83 86.92 93- IS 13.08 6.82 86. 59 93.04 I3-4I 6.96 86.16 92.50 13.84 7- 50 36.53 93.28 13-47 6.72 86.61 92.91 13-39 7.09 86. 31 93- 00 13.69 7.09 86.54 92.96 I3-46 7.04 85.90 92.94 14.10 7.06 85. iS 92.50 14.82 7.50 35-37 92.62 14.63 7-38 85-13- 92.56 14.87 7-44 85.06 92. 74 14.94 7.26 £ = a c 2 3-13 -85 3.06 •S3 3.08 .82 3.18 .S6 3-i3 •S3 3.22 .38 3-29 .87 3-45 .87 3-36 .89 3.4S .91 3.38 .89 3.48 ■94 3-44 .90 3-59 ■94 3-46 .88 3.62 •97 3-93 1 01 3-99 1.03 4.00 1.04 3-S6 1.04 2 •49 .64 2 .48 • 53 2 46 62 2 53 65 2 56 .62 2 49 73 2 68 61 2 77 68 2 68 68 2 76 •72 2 62 76 2 75 73 2 64 80 2 90 69 2 7i 75 3 06 5 6 3- 13 80 3- 14 S5 3- 18 82 3- 10 76 5-71 5-66 5.78 5.65 5.58 5 55 = .63 5- 61 5-51 5o8 5-54 5.68 5-71 5-79 5-59 5-59 5.62 5-58 5-73 # 5-7o 6.26 6.27 5-74 5.46 5.65 5.SS 5-75 5-71 5.60 5-76 5-93 5-75 6.04 6.18 5.64 6.04 5-77 6.06 5-33 5.86 COW'S MILK. 7i In a series of analyses made in another year, the pro- teids were further separated and the range for the year was: Total solids, 12.29 to 13.39 per cent; fat, 3.40 to 4.10 per cent; casein, 2.19 to 2.26 per cent; albumin, 0.28 to 0.38 per cent ; albumoses, 0.30 to 0.50 per cent. Babcock and Russell in 1897 published the following analyses of the proteids of many samples of cow's milk: M 5 C iose tone en. nt. S c c = = c c ° S £ " 3 u O ° J3 O-i •- M I- E"22 S 3 £ a i_ J3 US) ■=fc efc 5 =-Ph ^PL, < ^ 0.46 o.34 0.08 2.87 2. £2 O.50 0.25 51 •43 .04 3 18 2.68 •25 • 25 52 .40 .04 3 25 2. 50 ■31 .50 53 •39 •05 3 3i 2.44 •31 .56 55 .46 .04 X 6.25 - 3 43 2.87 •25 • 31 55 .46 •05 (by 3 43 2.87 •31 •25 56 •45 .04 author) 3 50 2.81 •25 •44 57 •43 .05 3 56 2.68 •31 • 57 58 •47 .07 3 62 2.94 •43 •25 53 .41 .08 3 62 2.56 •50 •55 59 .44 .04 3 6S 2-75 •25 .68 60 .46 .04 .70 J 3 4 75 2.87 .25 .63 72 .56 50 3- 50 •44 •56 39. Cream. — The fat globules of milk being much lighter than the other ingredients of the milk have a ten- dency to rise to the surface if the milk is allowed to remain undisturbed for any length of time. The separa- tion of the fat from the other ingredients of the milk is not complete, so cream is a mixture of milk elements in which fat greatly predominates. 4°- Cream Separating. — There are three methods of separating cream from milk. (1st) The shallow-pan sys- tem in which the milk is poured into wide, shallow pans; (2d) the deep-setting system, in which the milk is put into tall, narrow vessels, and allowed to stand; and (3d) the 72 INFANT FEEDING. centrifugal process in which the milk is run through a bowl which revolves at a high rate of speed. 41. Gravity Cream. — Cream that is allowed to rise naturally and is then skimmed by hand is called gravity cream. The separation of cream in the shallow-pan sys- tem is not very complete, and this system is not used much in producing cream for market. Strange to say, if milk is put into tall narrow vessels and placed in cold water at 45 F., the cream rises quickly and completely, the skim milk often containing not over 0.2 to 0.4 per cent of fat. This system is well illustrated by bottled milk, on which the layer of cream can usually be plainly seen. 42. Time Required for Cream to Rise. — If milk is placed in cans or bottles immediately after milking, before it has had time to cool, the separation of cream is rapid. At the end of four hours nearly all the cream that will rise will have risen ; but if the milk has been stirred and cooled before it is set for the cream to rise, the separation will take many hours longer and will not then be as complete (132). Other conditions affecting the separation of cream are the size of the fat globules, the passing of milk through a centrifugal machine as is sometimes done to remove dirt, and heating the milk. The smaller the fat globules the longer time is required for the cream to rise. In the milk of certain breeds of cows the fat globules are very small; such milk does not cream well. In rich milks, containing over four and one-half per cent of fat, the fat globules are larger and creaming is rapid and complete (36). Passing milk through a centrifugal machine breaks up the natural arrangement of the fat globules ; and gravity COW'S MILK. 73 cream from such milk separates slowly and incompletely, is very thin and limpid, and apt to deceive in richness one who has not tested it. Such cream, containing over Fig. 8. — Microscopic Appearance of Normal Milk. (Babcock and Russell.) Fat globules in clusters. Fig. 9. — Microscopic Appearance of Centrifuged, or Heated Milk. (Babcock and Russell.) Fat globules not in clusters. twenty per cent of fat, is often apparently not thicker than rich milk. Heating milk also prevents its creaming well. 43. Centrifugal Cream. — The first centrifugal cream 74 INFANT FEEDING. separators were simple buckets of milk which were whirled until the cream rose, when it was skimmed by hand. Later a circular bowl was devised, which when revolved three thousand to five thousand times a minute caused a rapid separation of cream. The milk arranges itself into several layers. The dirt and heavy particles, such as epithelium and manure, are thrown against the side of the bowl ; next u Fig. io. — Centrifugal Cream Separator. (Wing.) a. Inflowing miik ; 6, outflowing skimmed milk ; c, outflowing cream. comes the skim milk, and then the cream which is lightest is nearest the centre of the bowl. A clear idea of the state of the milk in a separator bowl can be had by imagin- ing a quart bottle of milk on which the cream has risen being laid on its side without the arrangement of the cream being disturbed. The bottom of the bottle with its sediment would correspond to the side of the bowl and the mouth of the bottle to the centre of the bowl. COW'S MILK. 75 Now imagine a small stream flowing from the layer of cream near the mouth of the bottle and another from the skim milk near the bottom of the bottle, with the bottle kept filled all the time by a fresh supply stream of milk that separated as soon as it entered the bottle into the layers of dirt, skim milk, and cream, and the centrifugal cream separator will be understood. The illustration shows a simple style of separator bowl in operation. The length of time the milk remains in the bowl of the separator can be regulated and the cream made richer or poorer in fat accordingly. The shorter the time the milk is in the bowl the poorer the cream is in fat. 44. Separator Slime. — After a quantity of milk has been passed through a separator there is found sticking to the inside of the bowl what is known as separator slime. Its composition is variable, but it generally consists of epithelium, mucus, pus, blood, dirt, manure, hair; and if the milk is slightly sour, of quantities of precipitated casein. There is always more or less of this separator slime, even if the best and cleanest milk is used. It is not necessarily filth, although when obtained from dirty milk it contains much filth. 45- Difference between Gravity and Centrifugal Cream. —When milk leaves the cow the fat globules are free ; but shortly after milking they form themselves into little groups, supposedly under the action of a substance similar to fibrin. When milk is passed through a separator or is heated for that matter, this arrangement of the fat globules is broken up (43). There is also a separation of the pro- teids. To quote Babcock and Russell: "A chemical ?6 INFANT FEEDING. analysis of fresh separator creams showed that from eigh- teen to thirty-eight per cent of the total protein was present in the form of albumoses and peptones," while they found, on an average, that in fresh whole milk 9.69 per cent of the protein was albumoses and peptones. Hence there is a great difference, both physical and chemical, between gravity and centrifugal creams; and, in the author's opin- ion, gravity cream from bottled milk is to be preferred for use in infant feeding on the principle that the less the milk is manipulated and the ingredients are separated, the better. In butter-making this separation of proteids and change in form of the emulsion of the fats in centrifugal cream is not a disadvantage, for butter can be made from centrifugal cream without the "ripening" or partial souring that gravity cream must undergo before butter can be made from it. For many commercial purposes, however, cen- trifugal or heated (Pasteurized) creams cannot be used. Charlotte russe and ice-cream makers and cooks insist on having gravity creams because they will " whip," while centrifugal or Pasteurized creams will not " whip." Cream Thickeners . — To overcome the objections thus inherent in centrifugal cream, Babcock and Russell in- vented a process of giving "body" to creams, which con- sists of adding a syrup of lime, which they call " viscogen," to the centrifugal or Pasteurized creams. Syrup of lime can be had at any drug store and contains six and one- half per cent of lime. A few drops of this syrup of lime will cause cream or milk to become thick and viscid, its action being on the mucoid proteid (35) of the milk — the distinctive property of mucin being that of forming mu- COW'S MILK. 77 cilaginous, stringy solutions when acted upon by a trace of alkali. Any one having much to do with milk or cream should try adding syrup of lime to both and should also taste them when thickened. The taste is distinctive but not unpleasant. Another method of thickening cream consists of add- ing solutions of gelatin. Such thickeners are sold by dairy supply houses under different names (see cream, al- buminoid) (63). 46. Condensed Milk. — There are two distinct kinds of condensed milk which are widely used — fresh condensed milk and canned condensed milk. Milk is first heated up to near boiling point and a large portion of water then removed by boiling at a low temperature in vacuum pans. The condensed milk is then filled into bottles or cans if it is to be sold in its fresh state; or cane sugar is added, and it is then filled into tin cans and hermetically sealed if it is to be kept for any length of time. During the past three or four years there has been a greatly increased sale of unsweetened condensed milk put up in sealed tin cans. These milks are limpid, yellow in color, and have a strong " cooked " taste. They are sold under the name of " Evaporated Creams," a misleading term, as many brands of condensed milk contain more fat than these so-called creams. The labels on the cans of evaporated cream usually state that it is simply pure milk thoroughly sterilized and reduced to the consistency of cream. These evaporated creams are apt to become putrid when diluted and exposed to the air, and for this reason are being put up in small cans, the contents of which will be used up quickly. 78 INFANT FEEDING. There has recently been devised a process of condens- ing milk without the aid of heat. The cream is first re- moved by a separator (43) and the skim milk is then frozen. As fast as crystals of ice appear the milk is stirred and in time becomes like slushy snow. The wa- ter in crystallizing throws out the proteids, sugars, and mineral matter of the milk as a syrupy mass. The frozen milk is then put in a centrifugal machine, such as is used in driving out the molasses from raw sugar, and the syr- upy mass of proteids, sugar, and mineral matter is thus separated from the ice crystals. The cream is now mixed with the syrupy mass and the mixture, when diluted with three parts of water, equals the original milk. As yet this condensed milk is not on the market, but if it becomes possible to render it sterile without the use of heat, so that it can be kept indefinitely, it is likely to become a very useful article of food. The following analyses of condensed milks furnished the author by Major Alvord, Chief of Dairy Division, United States Department of Agriculture, are of milks bought in San Francisco. Only four States, Illinois, New York, Ohio, and Oregon, have laws (79) relating to the quality of condensed milk, so any kind of condensed milk can be sold in the other States. These analyses do not represent all the brands in the market by any means, but they do show the range in quality likely to be met with. Any of the evaporated creams or unsweetened condensed milks may be tested in a few moments by the fat and specific gravity test (75) when diluted with two parts of water, quite accurate results being obtained. Sweetened condensed milks cannot be easily tested in COW'S MILK. 79 this way, as the excess of sugar interferes with the fat test. Unsweetened Condensed Milk. Whole Milk (so-called Evaporated Creams). 6S.27 69.17 69. 5 S 72.78 72.92 Fat. Proteids. Milk sugar. Solids not fat. Cane sugar. Ash. IO.IO 7-36 II.03 r.85 IO.4O 8.OI 20.43 1.79 9.02 7-77 10.62 I.80 9-37 7.66 17.85 1. 61 8-34 6.00 IS. 74 I. 71 Brand. Ideal. California Poppy, Highland. Lily. Red carnation. Evidently Skimmed or Partly Skimmed Milk. 74.29 1.80 8.97 23.91 2.39 80.58 5.70 7.02 13.72 1.69 Monarch. "99." Sweetened Condensed Milk. Whole Milk. Water. Fat. Proteids. Milk sugar. Cane sugar. Ash. Brand. 23.70 25.25 26.03 27-52 28.41 IO.82 ro.62 8-54 8.81 S.44 8.54 7.90 7.17 7.4S 7.23 14.17 12.53 12.45 12.77 II.69 39-85 40.56 41.82 41.06 4L52 2.13 I.84 I.87 I.63 I.80 Milk Maid. Nestle's. Gold Lines. Eagle Falcon. Eagle. Evidently Skimmed or Partly Skimmed Milk. 25.68 0.71 10.35 16.85 43.09 2.48 Cowslip. 25.88 0.96 10.64 27.38 34.07 2.56 Snake. 28.48 0.60 7.90 18.76 41.77 2.04 Farm. 29.67 2.47 10.45 19.05 36.00 2.29 Pearl. Condensed Creams. Water. Fat. Proteids. Solids not fat. Ash. Brand. 59.60 65.26 69.84 34.19 2S.26 23.83 6.21 6.48 6.33 0.53 O.56 O.67 Dahl's Gold Medal. Empress. California. CHAPTER XI. BACTERIOLOGY OF MILK. 47. Practically all of the changes that take place in milk that is kept for any length of time are the result of bacterial growth. The mere presence of bacteria in milk, even in large numbers, however, does not necessarily mean that the milk is harmful and unfit for use as food. A great deal of misapprehension exists on this point, and it can be removed only by a better knowledge of the func- tion and properties of bacteria. To many, bacteria sug- gest disease, and it has been thought that all bacteria should be destroyed; but now it is known that their in- discriminate destruction would prove to be a great calam- ity, as bacteria are absolutely essential to the life of plants and animals, the function of most bacteria being to reduce to gases, and soil, which is a mixture of earth and decom- posing organic matter, all lifeless organic matter, which then serves as food for plants, and these in their turn nourish all animal life. Bacteria serve other useful and valuable purposes. The delicate flavor of June butter is caused by bacterial action, and the manufacture of cheese is largely, if not wholly, dependent on the growth of bac- teria in milk. It is true that disease is caused by some kinds of bacteria, but all bacteria should not be con- demned and destroyed, even if this could be done, be- cause a few species cause disease. BACTERIOLOGY OF MILK. 81 o° Fig. ii. — Showing Budding of Yeast. (Conn.) U 8 As bacteria are everywhere present and are sure to be found in milk, a knowledge of their nature and of the conditions under which they gain ac- (^V f~^\ Jl cess to the milk and cause it to change ^^"^ ? u y or become harmful is essential. ^J S*\ 48. Bacteria. — Bacteria are micro- scopic, unicellular, colorless plants, be- longing to the class called fungi. They are closely related to ^ the yeasts, but are yj Q_J smaller and also differ from the yeasts in r\ their methods of reproduction. Yeasts multiply by budding, while bacteria mul- F,G f 12 T : -Showi "£ Fis ; x J J " sion of Bacteria. (Conn.) tiply by two different methods : 1st. By fission, in which the cell divides through the centre, pro- ducing another full-fledged bacterium. 2d. By specula- tion, in which spores are formed in the interior of the cell, which breaks up and sets them free. These spores when placed in favorable surroundings germi- nate and become ac- tive bacteria. Not all species of bacteria are spore- bearing, and this fact has great importance in the preservation of milk and food ; for while active bacteria are almost with- out exception easily destroyed by a moderate degree of heat, spores in water or milk are not destroyed by boiling. They may be dried and kept for months or years, and then 6 Fig. 13. — Showing Formation of Spores. (Conn.) 82 INFANT FEEDING. when placed under favorable conditions will germinate and develop into active bacteria. Many of the harmful changes in milk are caused by spore-bearing bacteria. #° Fig. 14. — a, Spheres; 6, rods; c, spirals. (Conn.) Classification of Bacteria. — Bacteria are divided ac- cording to their form into three groups: 1. Spherical bacteria — coccus. 2. Rod-shaped bacteria — bacillus and bacterium. 3. Spiral bacteria — spirillum. Fig. 15 — a, Streptococcus; £•, micrococcus : c, sarcina. (Conn.) Spherical bacteria are further classified according to the way in which they group themselves .during the proc- BACTERIOLOGY OF MILK. 83 ess of division, as streptococcus, in chains; micrococcus, in irregular masses, and sarcina, solid masses in groups of four. 49. Bacteria that grow best in the presence of oxygen or air are called aerobes ; those that grow best in the absence of oxygen or air are called anaerobes. Bacteria which will grow only under one of these conditions are called obligate aerobes or anaerobes, while those s'pecies that will grow either in the presence or absence of oxygen are called facultative aerobes or anaerobes. The greater number of species of bacteria attack and live upon lifeless organic matter and are called saprophytes ; those species that attack living matter are called parasites. 50. Rate of Growth of Bacteria. — Bacteria increase in numbers at a prodigious rate. If nothing interfered, in twenty-four hours a single bacterium would produce about seventeen million others. This rate of increase is not met with in practice ; but, according to Conn, a specimen of milk containing 153,000 bacteria to the cubic inch con- tained twenty-four hours later 85,000,000, and a sample of fresh cream, containing 44,000 bacteria to the cubic centi- metre, contained 1,300,000,000 when sour enough to churn. The rapidity of increase depends largely on the tempera- ture. Below 45 F. there is comparatively little growth of bacteria; but as the temperature approaches ioo° F., the rate of growth increases rapidly. 5'i. Food of Bacteria. — Most bacteria must have a food supply of nitrogenous matter (proteid), carbohydrates (sugar, starch, or cellulose), mineral matter, and water. Furthermore, their food must be in a soluble form so that it can pass through the cell wall of the bacteria and be 84 INFANT FEEDING. not too concentrated. Bacteria cannot grow in substances as thick as syrup. Bacteria that can attack insoluble matter secrete enzymes that digest or convert the insolu- ble food material into assimilable forms. Thus in milk some species of bacteria will secrete rennet that will curdle the casein of milk, and trypsin that will dissolve or pep- tonize it. Other bacteria also secrete enzymes that will digest or decompose starch, sugar, cellulose, fat, urea, and other substances. 52. Souring of Milk. — As ever} 7 one knows, the most common change in milk is souring. Milk sours because several species of bacteria attack the sugar of the milk and convert it into lactic acid, which throws the casein out of solution (37). These bacteria may be classed as harm- less bacteria, for sour milk is a wholesome article of food and is used in cooking. Before baking powder became so common, sour milk was used with baking soda to make cake and biscuit rise. It is popularly believed that thunder causes milk to sour, but it has been found that the thunder or electricity of the air has nothing to do with the souring of the milk, but that the atmospheric conditions during a thunder storm are favorable to the growth of lactic-acid bac- teria. Fresh milk always contains several species of bacteria, and if the milk is warm enough they commence to grow at once. The conditions in the milk are generally most favorable for the growth of the species that attack the sugar and produce lactic acid ; and if there are any of these bacteria present, as is generally but not always the case, they soon outstrip the other species and kill them BACTERIOLOGY OF MILK. 85 off; hence after a few hours an examination of the milk will often show ninety-nine per cent of the bacteria in the milk to be of the souring variety. When bacteria that cause souring are not present, the other species which attack the fat and proteids of the milk grow and produce rancidity of fat and many changes in the proteids. 53. Peptonizing Bacteria in Milk. — When the proteids of milk are attacked by bacteria, they may be first curdled by rennet and then peptonized by trypsin, both secreted by bacteria, or the proteids may be peptonized without first being curdled. Such milk does not sour, but acquires a bitter taste. Bacteria that produce these changes are normally present in milk, but are usually held in check by the souring species; sometimes, however, poisonous products are produced by bacterial action on proteids of milk. 54- Decomposition of Proteids. — The decomposition of proteid matter is brought about chiefly by the action of decomposition bacteria. When the process of decomposi- tion is caused by aerobic bacteria in the presence of an abundance of air, it is called decay and the proteid matter is reduced to simple harmless forms; but, when the de- composition is caused by facultative aerobic or anaerobic bacteria in the absence of an abundance of air, the process is called putrefaction. Here the proteid matter is not completely reduced to simple harmless forms ; foul-smell- ing gases are evolved and oftentimes substances that are intensely poisonous are also produced. These poisons may be secretions or excretions of the putrefactive bac- teria, or partially reduced proteid matter. Under the ac- tion of aerobic bacteria, in the presence of plenty of air, 86 INFANT FEEDING. these gases and poisons are destroyed. The process in- volved in the decay or putrefaction of proteid matter is not understood. Putrefactive bacteria are present every- where, but particularly in rich soil and in manure. A gram of rich soil may contain 100,000,000, and a gram of fresh cow's manure as many as 375,000,000 bacteria, most of which will cause decomposition in proteid matter. This fact suggests the importance of keeping cows and stables clean. Other Bacterial Changes in Milk. — Slimy milk is caused by bacteria found in water, and " gassy " milk by bacteria found particularly in manure particles. Soapy, blue, red, and yellow milks are also the result of bacterial action, but are not common (see Fig. 7$- The bacterial changes of milk may be summed up as souring, pep- tonizing, pu- trefactive, and the development of odors, bit- ter taste, sliminess, soapiness, colors, and gases. Bacterial Diseases Trans- mitted by Milk. — Typhoid fever is easily transmitted by infected milk. Outbreaks of diphtheria and scarlet fever have been traced to milk supplies, and tuberculosis may 16.— Slimy Milk. (Russell.) Fig. 17. — Udder and Teat. (Russell.) BACTERIOLOGY OF MILK. 87 possibly but not necessarily be caused by milk containing tubercle bacilli (see Chapter XV.). i°s? How Bacteria Get into Milk and Increase in Numbers. 55- From the Cow's Udder. — Just inside the cow's teat is a small cavity that always contains a small quantity of milk. During the intervals between milkings bacteria from the air lodge on the moist teat and make their way into this cavity where they grow. To quote Russell : " As a rule the number of different species found in the fore milk is usually small, not more than one or two forms being pres- ent at any time. As to the character of these forms data are conflicting. Har- rison reports finding peptonizing bacteria in some, and Mar- shall states that or- ganisms are found that resist pasteuriz- ing. . . . Bolley in thirty experiments found twelve out of sixteen species to belong to the lactic-acid class. ... If the fore milk is received into a separate vessel and kept protected from the air, it will be generally noted that it sours more rapidly than the re- mainder of the milk." In the report of a. series of bacterial examinations of milk, D. H. Bergy (Penn. Dept. Agr. Rept., 1900) states: "Milk taken directly from the Fig. 18. — Bacteria from Cream. (Conn.) c and d produce good butter. 88 INFANT FEEDING. udder in the ordinary way and collected in sterile test tubes was always found to contain bacteria of the group streptococci. The number in the first milk drawn was usually greater than [in] the latter portion." Strepto- cocci are usually looked upon by physicians as dangerous bacteria, but it has been found that good butter flavor is produced by some species of streptococci (Fig. 18). Fig. iq. — Tuberculous Udder. (Russell.) If the first few jets from each teat are thrown away, the remaining portion of the milking will be quite free from bacteria, provided the cow has no disease of the udder. No milk from a diseased udder should be used as food. Tuberculous udders always secrete milk containing tu- bercle bacilli, and although there is some doubt about bovine tuberculosis infecting human beings through milk, no risk should be taken. When a cow's udder is tuber- BACTERIOLOGY OF MILK. 89 culous, it is time to stop the use of her milk, whatever may be said of the safety of the milk from cows that simply react to the tuberculin test.* 56. From the Cow's Body. — If the cow's body is not kept clean, more or less dirt is bound to be loosened and to fall into the milk pail, along with some hairs, during the process of milking. On a single cow's hair several hun- dred bacteria have been counted, and, as previously stated, soil and cow's manure, which is the dirt usually found on the cow's body, contains millions of bacteria per gram (54). If the cow has been wading in slimy, stagnant water, the scum from this water dries on the cow's body and some of it will get into the milk; this dried scum is particularly injurious to milk. The bacteria that get into milk with filth are, as a class, the ones that cause the most damage to milk as a food, for many of these species decompose or putrefy the proteids of the milk. They can be kept out of the milk by keeping the cows clean. Example f : Milk from four dirty cows in a clean barn with clean milkers gave an average of ninety thousand bacteria to the cubic centimetre. Milk from four other cows of the same herd, carefully cleaned and milked by the same man, gave an average of only two thousand. 57- From Dust. — Stable dust contains enormous numbers of bacteria, and if the cows are eating dry hay, or if the milker's clothes are dusty, the milk will *This test consists of injecting into an animal certain products de- rived from tubercle bacilli. If the animal is tuberculous they cause a rise of temperature. f Report of the summer work of the Milk Commission of the Medical Society of the County of New York. (Bacterial examinations made by Dr. Sarah Belcher.) 9 o INFANT FEEDING. receive a great many bacteria with the dust that is sure to settle into the milk pail. Dust can be kept out of milk by wiping the cow with a damp cloth and by sprinkling the stable. Example * : Milk from each of twelve cows in a stable showed low bacterial count except from one which stood next to a pile of dry feed ; her milk contained one mil- lion bacteria to the cubic centimetre. 58. From the Milker. — If the milker's hands are chap- ped or not clean, or if he is diseased, or is nursing a person Fig. 20. — A, a, Improper joints in dairy utensils. B, Proper joints closed with solder. (After Russell.) suffering from some infectious disease, the milk is more than likely to be infected by him. It is in this way that typhoid fever, scarlet fever, diphtheria, and infectious dis- ease germs find their way into milk. Milkers should wear white duck suits or blue overalls that are kept clean by frequent washing. 59- From Dairy Utensils. — Any part of a milk pail, vat, cooler, can, bottle, or bottle filler that cannot be kept perfectly clean, always contains many bacteria that will infect any milk they may come in contact with, and for * See last note on page Sg. BACTERIOLOGY OF MILK. 91 this reason all dairy utensils should have perfectly tight smooth seams and joints; even then it is almost impos- sible to keep the best-made utensils free from bacteria. Washing utensils with ordinary well water or brook water may infect the milk with typhoid germs; they should be washed with boiling water and steamed if possible. Example*: With ordinary milk pail and strainer the bacterial count was eighty thousand; with sterilized pail and strainer the same day, in the same barn, and with the same cows five thousand bacteria to the cubic centi- metre were counted. 60. By Growth. — When the milk leaves the cow it is at a temperature of nearly ioo° F., which is the ideal tempera- ture for rapid growth of bacteria. If the milk is allowed progeny or A /> 10 to 13 " ' Ovamucoid / Salts 0.7 " Fats "1 Soaps T .... V Trace. Lecithin Cholesterin 1 82 INFANT FEEDING. There are many subdivisions of these ingredients of both the yolk and white of eggs that are not of interest here. It will be noticed that there is an absence of carbo- hydrates in eggs. The function of carbohydrates in food is to furnish heat. As the mother bird sits on the eggs and keeps them warm during incubation, the developing chick has little need for heat-producing food, and it is not found in eggs. Whole eggs may be looked upon as a tissue-building food, but not as a complete food; for in- fants or adults need in addition liberal quantities of carbo- hydrates. White of egg should not be used as the sole source or main source»of proteid for infants, as it cannot build up cells. Experiments in feeding animals with white of egg have shown it not able to support life. In certain forms of indigestion it may be used temporarily with benefit. Flavor of Eggs. — The flavor of eggs may be the result of two causes: i. From the hens eating highly flavored or animal food. 2. From changes that take place in eggs that are kept for any length of time, probably due to bacterial infection. Mai'ket Eggs. — Eggs for the New York market, and probably for other large cities, come from a wide area of country and are divided into four grades. First Grade, or Hennery Eggs. These are from se- lected breeds of fowls and are from three to five days old when sold. Only a few high-grade stores have these, and they bring from ten to fifteen cents a dozen above the price of the next grade. MEATS AND EGGS. 183 Second Grade, or New Jersey, New York, and Penn- sylvania State Eggs, which are about a week old when they arrive in New York. These are what would be gen- erally called first-class eggs and are kept by the best stores. Third Grade, or Packing Eggs. These are from Illi- nois, Indiana, Iowa, Michigan, and Ohio, and are at least two weeks old when they arrive in New York. These are the eggs found in the general run of stores. Fourth Grade, or Kentucky, Missouri, and Tennessee Eggs. The hens that produce these eggs are not care- fully fed, being allowed to run at large and eat anything they can find, consequently the eggs are strong in flavor and watery and spoil easily. These are the cheapest eggs that are sold. Preservation of Eggs. — As the shells of eggs are por- ous, bacteria find their way into eggs and set up putrefac- tive changes which soon spoil them. If the egg lies on one side too long the yolk will move to that side and stick to the shell. To preserve eggs from these changes they are often kept cool or immersed in a solution of silicate of soda (water glass) or lime water, which fills up the pores. Eggs kept in silicate of soda solution have been kept three and one-half months without apparent change in flavor or in position of the yolk. "When such eggs are boiled, they are apt to burst open as the steam generated inside the shell cannot escape through the closed pores. To overcome this objection egg dealers prick the shell. Candled Eggs. — A perfectly fresh egg, when held be- fore a candle in a dark room, appears almost translucent. i8 4 INFANT FEEDING. Cloudiness denotes a change in the egg; when decayed or rotten, it appears very dark or black. This is a very simple way of selecting fresh eggs. An absolutely fresh egg should be obtained in order to get a clear idea of how it appears. PART III. CHAPTER XIX. BREAST FEEDING — DIET AND CARE OF MOTHER — ELIMINATION OF DRUGS IN MILK— CARE OF NIPPLES— CONTRAINDICA- TIONS— MENSTRUATION— P REGNANCY— WET-NURSING — WEANING AND MIXED FEEDING. 114. When it is possible for the mother to nurse her offspring, comparatively little difficulty will usually be experienced in properly nourishing the infant. In view of this fact all possible foresight should be used in fitting the prospective mother for her duties. For several months before expected delivery, the nip- ples should be gently rubbed between the thumb and fin- gers, depressed or misshapen nipples being thereby drawn out and developed ; this also toughens them and prevents possible tenderness or fissure that would interfere with nursing. Tight clothing over the breasts should be avoided. Bathing the nipples with boric acid or borax solution, one-half teaspoonful to a cup of water, promotes cleanliness and thereby tends to avoid possible infection and soreness during the nursing period. After the mother is sufficiently rested from the labor the baby should be put to each nipple. If this does not satisfy, and the infant becomes fretful or restless, a tea- spoonful or so of boiled water may be given. This not only quiets the infant, but helps to wash out the digestive 1 88 INFANT FEEDING tract and kidneys. For the first day or two the infant may be put to the breast at three-hour intervals during the day and at four- to six-hour intervals at night ; after this every two hours during the day and once or twice at night. The infant should not be allowed to occupy the bed of the mother at night, as this is a common cause of too frequent nursing. Regularity of feeding is essential, us tlie composition of milk varies zvith unequal intervals between nursings. The shorter the intervals, the richer the milk is in fat, so it is well each day to write down the hours at which nursings are to be given, as 5, 7, 9, 11 a.m., *> 3» 5» 7> 9 p - M -> e t c - When the amount of milk is suffi- cient, the baby will suckle for fifteen or twenty minutes and then drop off contentedly to sleep. If, on the con- trary, the baby tugs at the nipple for twenty-five or thirty minutes, and then frets after leaving it, there has not been sufficient milk secreted. 115. In cases in which the milk flow is scanty or does not agree with the infant, particular attention should be paid to the diet and hygiene of the mother. Southworth, who has made a special study of this subject, states that much more than is generally believed can be accomplished in this direction. Nursing is a purely animal function and a great deal can be learned from the study of the secretion of milk by cows. Here it has been found that secreting milk is hard zvork, and that a cow in milk needs as much food as an ox doing heavy work. The best cow is one whose digestive and excretory systems are highly developed and who has no tendency to lay on fat. Such a cow is virtually a milk manufactory. Therefore it is useless to expect any mother to supply BREAST FEEDING. 189 thirty to forty ounces of milk daily, containing about five ounces of solids, the proteid of which is equivalent to about a quarter of a pound of meat, unless she eats and digests a liberal quantity of food. The diet of the mother should consist of plenty of plain, easily digested food, meat, milk, eggs, and well- cooked cereals (102) predominating. Tea and coffee should be withheld, as they have a tendency to diminish the feeling of hunger and thus cause less food to be eaten and digested, while cocoa and chocolate may be drunk in moderation. Liquid malt extracts may have a benefi- cial effect by toning up the digestive system, thereby en- abling more food to be digested, but not by any particular property of making milk. Southworth recommends to have the mother drink between meals a bowlful at a time of a well-cooked and salted gruel made from yellow corn- meal. This not only contains nourishment and water that is needed, but undoubtedly has by its coarse particles a beneficial effect in increasing the amount of faecal mat- ter (27) and thus keeping the bowels regular. 116. It is well known that volatile substances in food readily find their way into milk and that the flavor of a cow's milk is often affected by her food ; also that under certain conditions urea is found in appreciable quantities in milk. For these reasons highly flavored food should be avoided and strict attention should be paid to the excretory organs, so that products shall not be thrown off with the milk which should pass off in the urine. Constipation in the mother should be overcome by the use of drugs if copious quantities of the cornmeal gruel do not relieve this condition. In selecting drugs 190 INFANT FEEDING. for this purpose, those whose principal action is on the muscular coat of the bowel, rather than on the glandular apparatus, should be chosen. Cascara is one of the best for this purpose. Anaemia should be overcome by gen- erous diet and the exhibition of iron. Great care must be exercised in the administration of drugs to nursing women, as they may be excreted in the milk. Thus morphine, mercury, quinine, iodide of pot- ash, and similar preparations, may have a marked effect. This is especially apt to happen when the mother is in a disturbed condition, and consequently the excretory or- gans and mammary glands are not in a normal state of equilibrium. 117. The great and sudden variations in composition of milk are the result of nervous influences, and as diges- tion is also greatly affected by anxiety, fright, fear, or other nervous disturbances, particular attention should be paid to keeping the mother in a cheerful state of mind and to seeing that her rest at night is not too much broken. As fresh air is very invigorating, a walk that stops short of fatigue or a drive with pleasant company will have a beneficial effect. 118. In cases in which the mother or nurse is robust and has a plentiful supply of milk that disagrees with the infant, it may prove advantageous to cut down the diet, particularly of proteids (meat, eggs, etc.), as they have a tendency to increase the percentage of fat and proteids in the milk. With the reduction of diet should go an increase of exercise, causing to be used up some of the excess of food eaten, and possibly the exhibition of sa- line cathartics. BREAST FEEDING. 191 If, with the means indicated, it is impossible to keep the infant steadily gaining in weight, four to six ounces a week, with good digestion and normal stools (156), one or two artificial feedings, alternating with breast feedings when possible, should be given daily, as will be explained later (122). 119. When from fissured nipples or other causes it is impossible for the infant to nurse, the milk may be drawn with a breast pump and fed by bottle or medicine dropper for a few days, until a return to breast feeding is possible. If an abrasion or slight fissure of ' lppe ied ' the nipple causes much pain to the mother, the use of the nipple shield for a day or so may give great comfort and allow healing to take place. The infant often rebels against its use, however, from the difficulty of pulling the milk through. The latter may be partly obviated by fill- ing the shield with warm water at the start, and at the same time massaging the breast, thus getting an easy flow of fluid. Between nursings the nipple must be carefully protected. 120. Contraindications for Nurs- ing. — Mothers with certain constitu- tional diseases, especially tuberculosis, should not be allowed to nurse their offspring. When the mother is pale and losing flesh and exhausted by suckling in spite of tonic treatment, the baby must not be continued on the breast. In nervous, excitable women, when every effort has been made to regulate the details of diet and living, and yet the baby does not thrive i 9 2 INFANT FEEDING. and gain after a fair trial, it is best to stop the breast. Nursing after Menstruation. — The question of nursing after menstruation has been resumed can usually be answered in the affirmative. Any disturbance is usually only temporary and may not recur at the next period. If, however, severe nervous and digestive disturbances regularly occur at each period and interfere with the nu- trition of the infant, it may be neces- sary to remove the breast entirely. Before this is done a trial may be made of giving the bottle during the time of menstruation and then resuming the breast. Intervening Pregnancy . — If preg- nancy intervenes it is usually best to give the baby other nourishment. There may be many exceptions, bow- ever, to this rule. Thus, if pregnancy occurs during the middle of a hot summer, when the baby is thriving, or in the case of a weak fragile baby with a tendency to digestive trouble, the breast may be con- tinued during the early period of pregnancy; while not ideal, this may prove the best method of feeding available. 121. Wet-Nursing. ,— In many cases in which a mother cannot nurse her infant, a wet-nurse is the best substitute. A wet-nurse is especially indicated when the infant is poorly developed and shows signs of digestive feebleness. The preferable age for the nurse is between twenty and thirty years, and multiparas usually do better than primi- Fig. 45. — Breast Pump. BREAST FEEDING. 193 parse, the former having had previous care of the suckling and general charge of infants, which may be of decided advantage. Too much disparity between the ages of the infants is not desirable, but a woman whose infant is under six months can usually suckle a new-born baby. One advan- tage of having a wet-nurse with an older infant is that a careful inspection of the nurse's infant will show how well it has thriven upon her milk, and also whether it has derived any constitutional disease, especially syphilis, from the mother. In every case a careful physical exam- ination of the applicant, as well as her infant, should be made by the physician. As changes in the composition of milk are largely the result of nervous influences and changes of diet, a woman of quiet, phlegmatic tempera- ment, in good health, is to be preferred, and when selected her diet should be as nearly as possible that to which she has been accustomed, and she should not be allowed to remain in idleness. A routine life should be established and maintained, as this will insure a uniform milk. The nurse's reward should be in some other form than grati- fication of her inclinations. This reward should be held out as an inducement for her to comply with directions. After her services are no longer required, she can obtain what she likes with the money she has earned ; but if she is furnished a diet she is unaccustomed to, she will in all probability over-eat and bring on either defective diges- tion or excretion, which will promptly disorder the diges- tion of the infant. Several nurses will sometimes have to be tried before a breast that completely agrees with the baby is found. 13 i 9 4 INFANT FEEDING. 122. Weaning and Mixed Feeding. — Many women who are good nurses show a deficiency in their milk, either in quantity or quality, by the eighth or ninth month. The bottle can here be given with advantage several times during the twenty-four hours, and especially at night, so that the breast can have a prolonged rest. The rate of gain in weight of the baby and the health of the mother will be the gauge as to when mixed feeding should be begun. In any case the baby should be removed entirely from the breast at the end of the first year. Toward the end of lactation the milk becomes unsuitable in composi- tion. This will be shown either by digestive disturbances or loss of weight, or both, on' the part of the baby. Wean- ing should be gradual, and as most babies will require the help of the bottle during the latter part of lactation, it is well to begin as soon as possible in giving one or two bottle feedings each day ; the baby will then be educated in its use, the mother will have more time to herself, and in case of her being ill, sudden weaning will not be neces- sary. If this method is employed, the change from breast feeding to bottle feeding will not cause inconvenience. Examination and Modification of Breast Milk. i 23. I n cases in which the mother's milk does not agree with a baby, as shown by constant colic, or stationary or losing weight, the breast should not be withdrawn until every effort has been made to find out and correct the cause of the trouble. Rotch has shown by repeated chem- ical analyses of mother's milk that much may be accom- plished by altering the diet and habits of life to render breast milk, when disagreeing, more fit for any given BREAST FEEDING. 195 1,030 / \ case. Each case must be carefully studied in every detail before finally deciding to remove the baby, from its mothers breast. There is no doubt that a large number of infants suffer from premature removal ; often with a little care and patience lactation could be continued dur- ing the normal term. The careful studies and analyses of Rotch have also shown that nervous, emo- tional women, or those who nurse their infants at prolonged or irregular intervals, or too frequently, or who are disturbed at night are apt to furnish a poor milk. Regularity in diet, excretion, exercise, rest, and nursing are always to be insisted upon ; sometimes it may be necessary to have the mother sleep in a room where she cannot be disturbed by the infant for a few nights, feeding it then by bottle. If, after these precautions have been taken, the milk continues to disagree, an analysis may throw light on the cause of the diffi- culty. Many analyses of human milk show it generally to contain fat 3 to 5 per cent, proteids 1 to 2 per cent, and sugar 6 to 7 per cent. Undoubtedly there is con- stant changing and variation in these percentages within certain limits, from day to day, and even from hour to hour, but the infant usually adapts itself to these variations, that doubtless per- form a useful function in the nutrition of the child. It is found that variations are mostly in the fats Fig. 46. — From Holt's "Infancy and Childhood." (Copy- right, 1897, by D. Ap- pleton & Co.) 196 INFANT FEEDING. «£ C3\ and proteids, the sugar remaining quite constant in quantity. 1. If fats and proteids are both low the infant is not getting enough nourishment, and of course cannot gain in weight. A more liberal diet for the mother is indicated. 2. If fats are low (below three per cent), and the proteids normal (one to two per cent), the mother must be fed more meat, eggs, and milk. It is useless to feed her excess of fats, as they will interfere with her digestion. 3. If proteids are high (above two per cent) the mother's meat and milk diet must be cut down. 4. If fat and proteids are both high, the diet must be cut down, partic- ularly the meats, and a liberal amount of out-of-door exercise must be taken. A brisk walk of a mile or two in the open air, twice daily, will sometimes correct an overrich milk. The physician must, how- ever, be specific in his orders, as exercise to the point of fatigue may be required to get results. When a complete analysis of the milk cannot be had, an approximate analysis may be made by the fat and solids not fat tests, described in the chapter on testing cow's milk. The fat is determined by the Babcock test, and the specific gravity with an ordinary urinometer. About an ounce of milk is required. The entire contents of a breast should be removed and mixed, or very errone- ||— 60 Fig. 47. — From Holt's "Infancy and Childhood." (Copy- right, 1897, by D. Ap- pleton & Co.) BREAST FEEDING. 1.97 ous impressions will be obtained, as the fat varies greatly in different portions of the secretion. Holt has devised an apparatus, consisting of a cream gauge and a small hydrometer, for testing as small a quantity as one-half an ounce of breast milk. The specific gravity is taken at yo° F., and the milk placed in the cream gauge ; after twenty-four hours the percentage of cream may be read. Five per cent of cream corresponds to three per cent of fat. The interpretation of results is shown in the following table by Holt: Woman's Milk. Specific gravity, 70° F. Cream — 24 hours. Proteids (calculated). 1. 03I % 8 to 12$ 5 to 6f c High (above 10$) Low (below 5%). . High 1.5*. Normal (rich milk). Normal (fair milk). Normal or slightly be- low. Very low (very poor milk). Verv high (very rich milk). Normal (or nearly so). Normal variations . . I.O32 Abnormal variations Abnormal variations Abnormal variations Low (below 1.02S) Low (below 1.028) High (above 1.032) High (above 1.032) Abnormal variations CHAPTER XX. METHODS OF SELECTING FOOD FOR ADULTS NOT APPLICABLE TO INFANTS— NUTRI- TION AND DEVELOPMENT OF THE DIGES- TIVE TRACT MUST BE CONSIDERED TO- GETHER. 124. When it becomes impossible to supply an infant with its mother's milk or that of a suitable wet-nurse, re- course must be had to some substitute food. This may be done in two ways: (1) By telling the mother or nurse to try everything that is suggested by kind friends until something is found that " agrees " ; or (2) scientifically to adjust the food so that the infant's future well-being will be conserved. A. V. Meigs, of Philadelphia, made the first attempt at scientific infant feeding by trying to adjust or modify cow's milk so that it would resemble mother's milk in composition. Later, Rotch, of Boston, emphasized the importance of systematic "percentage feeding," which consists of trying to make from cow's milk a mixture that contains accurate percentages of fat, proteids, carbohy- drates, mineral matter, and water, and varying these per- centages to suit the requirements of each particular in- fant. Other workers have contributed their quota to the advancement of scientific infant feeding with the result that many formerly accepted beliefs and doctrines have FOOD FOR ADULTS INAPPLICABLE. 199 been modified or completely abandoned. At present it is not accepted that there is one, and only one, way of sci- entifically feeding an infant. While there may be differ- ences of opinion as to methods of feeding, there are cer- tain principles involved which are beyond dispute and about which there can be only one opinion. 125. It has been shown (1) that true growth consists principally of an increase of protein in the body by a proc- ess of cell division (2), and the addition of mineral mat- ter to the bones. (2) That protein cannot be elaborated by the infant, but must be taken in as such with the food. (3) That there are many forms of protein, some of which are not tissue builders and can only put off the time when death will result from starvation (24). (4) That the first demand of the animal organism is for heat-producing food, and that during starvation normal heat is kept up by de- struction of the tissues (22). (5) That the function of fat and carbohydrates in the body is to produce heat (19). It follows that one of the first problems of scientific feeding is to determine the quantities and quality of the protein (tissue builder) and fat and carbohydrates (heat producers) needed for a given individual. This problem has been pretty well worked out for adults, and is gener- ally performed as follows: 1. From the quantity of ni- trogen in the urine during a period of fasting is deter- mined the amount of protein used up daily. There is no advantage in feeding more than this quantity to an adult as it is only excreted (20). 2. From the quantity of oxygen consumed is calculated the quantity of heat produced. 200 INFANT FEEDING. The standard for measuring heat values in dietetics is called a large calo7 r ie and is the amount of heat required to raise the temperature of one litre of water (2.2 lbs.) i° Cor i.8° F. The heat produced by the combustion of 1 gm. of protein is about 4.1 calories; of 1 gm. of carbohydrates, about 4.1 calories; of 1 gm. of fat, about 9.3 calories, or about two and one-quarter times that of either protein or carbohydrates. It has been found that a man doing ordinary muscu- lar work requires daily about 125 gm. (= 4 oz.) of protein and enough other food to produce about 3,000 calories. In selecting the food for such a man it is only necessary, theoretically, to see that his food contains 125 gm. of digestible protein and enough heat-producing food to pro- duce 3,000 calories. Adding the results obtained by mul- tiplying by 4.1 the weight in grams of the protein and carbohydrates, and by 9.3 that of the fat contained in any food, will give the total number of calories it will produce. Tables have been prepared showing the composition of most articles of food in general use, expressed in per- centages of digestible protein, fat, and carbohydrates, and it is a simple matter to calculate from these an- alyses the quantities required properly to nourish a person. For a healthy adult there are many articles of diet that are interchangeable, weight for weight almost, as their composition and digestibility are practically the same ; for this reason it makes little difference which article is used. FOOD FOR ADULTS INAPPLICABLE. 201 The following analyses by Atwater illustrate this statement: Corned rump of beef. Turkey Shoulder of veal Halibut Fat, per cent. 5-i 5-9 7-9 4-4 In preparing food for infants this method of selecting food cannot be employed, as will be explained further on. The proportion between the digestible protein and heat-producing elements in food is called the nutritive ratio and is thus determined. As fat has about two and one-quarter times as much fuel value as carbohydrates, the weight of the fat is multiplied by two and one-quarter and added to the weight of the carbohydrates. The pro- portion between the weight of the protein and the weight of the heat producers, calculated as carbohydrates, is the nutritive ratio. Example. A food contains: Fat, 2 per cent ; protein, io per cent ; carbohydrates, 50 per cent. Fat, 2 per cent X 2^ = 4.5 per cent, equivalent in carbohydrates. Carbohydrates, = 50.0 per cent Nutritive ratio, 1-5.45. 54.5 per cent -=- 10 per cent protein = 5.45. This is about the ratio required by adults. There is a wider nutritive ratio in human milk, which w 7 e should strive to imitate, than in an adult's food, as can be seen by a glance at analyses of this milk that are within the range of variation : Human Milk. Fat, per cent. Proteid, per cent. Sugar, per cent. Nutritive ratio, 1-12.75. Nutritive ratio, 1-8. 202 INFANT FEEDING. In human milk not only is there a variation in compo- sition, but also in the nutritive ratio. The much greater proportion of heat-producing elements in the infant's nat- ural food than in the adult's food is in part accounted for by the fact that there is a much greater radiation of heat from an infant's body ; metabolism is also much more active. At first thought nothing seems more rational in arti- ficial infant feeding than taking the milk of some of the lower animals and adjusting the percentages of fat, pro- teids, and sugar, and the nutritive ratio, so that they shall approximate those of human milk. Adjusting diets for adults on this percentage and nutritive ratio plan is very successful, but unfortunately not so successful in feeding infants, as it is often impossible for a young infant to digest the same percentage of the proteids of cow's milk as is found in woman's milk. In feeding adults, in whose fully developed digestive systems a great variety of foods can be digested equally well, it is only necessary to see that enough of fat, pro- teids, and carbohydrates are furnished to maintain the body. In feeding infants or young animals, whose digestive systems are not fully developed, it is not only necessary to supply the proper quantities of nutritional elements, which include more ingredients than fat, proteids, carbo- hydrates, and mineral matter, but they must be in such form as normally to develop the digestive tract. It has been shown in chapters IV. and VIII. that the milk of each species of animal is highly specialized for these two purposes. For these reasons it is not to be expected FOOD FOR ADULTS INAPPLICABLE. 203 that a perfect substitute for human milk will ever be pro- duced. The most that can be done is to provide a food whose composition is as nearly like human milk as our imperfect knowledge of milk permits us, to make, and to have it in such form that it will allow a normal use and development of the digestive tract. 126. Development of the Digestive Tract. — When an infant or any young suckling animal is born it has never used its digestive system, its nourishment having been received from its mother's blood stream. For the first few days afterbirth the mammary glands do not secrete milk, but colostrum, which is quite another thing. The function of colostrum seems to be to start up the digestive process, as there is a gradiial change from colostrum which requires little di- gestion, into milk which requires digestion. This change has been better studied in cow's colostrum than in that of other animals, for obvious reasons. The composition and character of the ingredients of cow's colostrum are different from those of milk (34). The proteids which are very high in quantity are not principally casein as in milk, which curds under the action of the rennet secreted in the stomach and requires con- siderable digestive effort, but are a mixture consisting 48.— Colostrum Bodies. (X 300.) a', Cells with nucleus ; a, cells undergoing fatty degenera- tion ; i>, cells containing large drops of fat ; REMOVE THIS QUANTITY AND MIX 1 OZ )IPPEF | FOR REMOVING TOP MILK I5T0Z. MUST BE REMOVED WITH A TEASPOON Figs. 55 and 56. — Quart Bottle of Milk Ready for Use, with Dipper. siphon is used to remove the milk from under the cream, the sediment — there is always some — goes into the infant's food, and the manipulation is rather difficult. * These dippers may be made by any instrument maker and are inexpensive to produce. PREPARATION OF FOOD. 229 Since the introduction of this dipper in 1899 many have suggested that the bottom would push the cream down into the milk. This seems plausible, but a great many assays of the milk after the cream has been re- moved show that this is not the case. 137- Diluents : Sugar Water, Plain Cereal Gruel, or Dextrinized Gruel. Beat up one to two heaping table- spoonfuls of barley, wheat, or rice flour with enough cold water to make a thin paste ; or use two to four heaping tablespoonfuls of rolled oats. Pour on a quart of boiling water and boiliox at least fifteen minutes, preferably in a covered double boiler as the gruel will not then burn. If the mixture is to be dextrinized after it is cooked, place the cooker in cold water, and when the gruel is cool enough to be tasted add one teaspoonful of diastase solution, or Cereo, and stir (133). This will thin the gruel. Strain, add salt to taste, and cool. Wheat, barley, and rice are well absorbed and should be used when the bowels move naturally. Oatmeal con- tains considerable coarse material that stimulates the bowels, and should be used when the bowels are con- stipated. 138. Sugar is not added to sweeten the food, but to supply heat-producing food. The dipper holds one ounce of granulated sugar; two level tablespoonfuls also equal one ounce. Three level tablespoonfuls of milk sugar equal one ounce. Either may be used. Preparation of Food. 139. Before attempting to prepare the food dip a strip of blue litmus test paper into the top milk. If the color 230 INFANT FEEDING. is only slightly changed the milk is fresh. If the color is changed to dull red, the milk is beginning to sour. It will be bright red if the milk is quite acid. For Young Infants. — One part of the nine-ounce top milk should be mixed with 3 to 8 parts of the diluent, and 1 part of sugar added to 20 to 30 parts of food ; granulated or milk sugar may be used. For Older Infants. — One part of the sixteen-ounce top milk should be mixed with 1 to 2 parts of the diluent, and 1 part of sugar added to 20 to 30 parts of food ; granulated or milk sugar may be used. In every instance begin on a weak mixture and gradu- ally decrease the dilution. Any quantity may be mixed, from about two ounces up to enough for twenty-four hours. In making up a small quantity a teaspoon, dessert- spoon, tablespoon, or the dipper may be used as a measure. Example : Mixture about 2 ounces one-fifth top milk. 2 teaspoonfuls of 9 ounce top milk (after being removed from bottle and mixed). 8 teaspoonfuls of diluent. 10 teaspoonfuls ; add one-twentieth sugar, or one-half teaspoonful. When the dipper is used, greater accuracy in quantity will be obtained and the result will be a definite number of ounces which is not the case when a teaspoon or table- spoon is used, as these vary in size. This does not affect the strength of the mixture, however. Example : Mixture 12 ounces one-third top milk. 4 dipperfuls (4 ounces) 16-ounce top milk (after being removed from bottle and mixed) . 5 dipperfuls (8 ounces) diluent. 12 dipperfuls (12 ounces) ; add one-twentieth of sugar, or one-half ounce. PREPARATION OF FOOD. 231 A quart graduate may be used in making up enough for all day ; all that is necessary is to know how many ounces of the top milk, diluent, and sugar are to be mixed. It is easy to remember that one part of sugar is to be added to twenty to thirty parts of food, and that two level table- spoonfuls of granulated or three level tablespoonfuls of milk sugar equal one ounce. The following mixtures illustrate the simplicity of preparing food by this method and are about the quan- tities and dilutions that will be needed for the great ma- jority of cases ; each can be prepared from one quart of milk. In feeding it is best to begin with a weak mixture and increase the strength as fast as the infant's digestion will permit. Progressive Increase of Quantity and Strength of Mixtures. r ... ... f 2 °z s - of 9 oz. top milk (after being re- 16 ounces — one-eighth top milk. ... . 1 ,, , . ,..■■. . ° r moved from bottle and mixed). Eight 2-oz. feedings ; one every two -, , ... , & J 14 ozs. of diluent, hours. r „ [ 1 oz. of sugar. * (3 ozs. of 9 oz. top milk (after being 21 ounces — one-seventh top milk 1 , , , , , . -, removed from bottle and mixed, tight 2%-oz. feedings ; one every two < „ r ... , 18 ozs. of diluent. hours. . „ I 1 oz. of sugar. . ,, . ... f 4 ozs. of 9 oz. top milk (after being re- 24 ounces— one-sixth top milk , c , , \ . , „. ,. moved from bottle and mixed), r-ignt 3-ounce feedings ; one every two - & '20 ozs. diluent, hours. I - „ I 1 oz. sugar. - - f ., .... f ° ozs. of goz. top milk (after being re- 30 ounces— one-fifth top milk ., L , , . „ . ,. moved from bottle and mixed) . beven 4-oz. feedings ; one every two and - - ... , . , J 24 ozs. of diluent, a half to three hours. , I \y z ozs. of sugar. 36 ounces— one-fourth top milk p ozs. of top milk from one-quart bottle. Six 6-oz. feedings ; one every three hours. ) 2 7 ozs. of diluent. ' i}4 ozs. of sugar.* * See Note on page 232. 232 INFANT FEEDING. (14 ozs. of top milk from one-quart 42 ounces — one-third top milk I bottle. Six 7-oz. feedings ; one every three hours. I 28 ozs. of diluent. I 2 ozs. of sugar.* , 1f , .,, f 20 ozs. of top milk from one-quart 40 ounces — one-half top milk ^ ^ o- c a c a- bottle, bix 7-oz. or five 8-oz. feedings ; one J .. .. , , ,, , ! 20 ozs. of diluent, every three to three and a halt hours. I 1 oz. of sugar. :: 48 ounces — two-thirds top milk t . c .„ n r 1 quart ol milk. Six 8-oz. or five 10-oz. feedings ; one < ■ . c ,■, & ' 1 pint of diluent. every three and a half hours. \ 140. After the food has been prepared it should be placed in separate nursing bottles and. these plugged with Fig. 57. — Nursing Bottle. 58. — Nursing Bottle, Preferable. Fig. 59. — Funnel for Filling Bottles. clean cotton and kept on ice or in a refrigerator away from meat or vegetables, where the temperature is below 50 F. The temperature of many refrigerators is above 6o° F. and the milk should then be put in the ice receptacle. When the temperature of the food is likely to rise above 6o° F., it is best to pasteurize the food — heat to 155 to 165 F. The Freeman pasteurizer or Arnold sterilizer may be * Two level tablespoonfuls of granulated sugar or three of milk sugar equal about one ounce. Granulated sugar may produce an acid gastric secretion, so it is often necessary to reduce it a little in quantity. PREPARATION OF FOOD. 233 Fig. 60. — -Freeman Pasteurizer. used for this purpose ; or a pasteurizer may be made from a six-quart tin pail. A false bottom is made by punching holes in a tin pie plate, which is to be inverted in the pail; this prevents the bottom of the bot- tles getting too hot. It is best to have a thermometer pass in- to the water through a cork fit- ted in a hole in the cover. The bottles are placed in water up to the level of the milk and the water is heated up to 165 F. The pail is then removed from the heat and covered with a cloth and al- lowed to stand for half an hour. Where a thermometer cannot be had, the water should be brought nearly to the boiling point before being removed from the heat. The bottles are then cooled by first being placed in luke-warm water and then in cold water. Pasteurized milk should be kept below 6o° F., or the spores in the milk will develop into active bacteria (48). A simple and practical method of keeping nursing bot- tles cool, sug- gested by De Forest, is to place cracked ice around them in the pasteurizer; this saves possible infection from food in a refrigerator. A quart bottle of milk may be pasteurized without dis- Fig. 61.— Arnold Sterilizer. 234 INFANT FEEDING. turbing the cream by setting it in a kettle or pail and heating as just described. Sterilizing (heating to 21 2° F.) is not employed so much as formerly, as the taste of the milk is greatly altered and certain chemical changes are also produced. There are no corresponding advantages that offset these objections (61). Fig. 62. — Home-made Pasteurizer. (Russell.) Fig. 63. — Pasteurizer for Bottled Milk. (Russell.) When conditions are such that pasteurization as de- scribed cannot be carried out, the milk may be brought to a boil, preferably in a double boiler, and then covered and allowed to stand for twenty minutes and then cooled. 141. Lime water added to the food often proves bene- ficial, especially when there is vomiting or when the milk is slightly acid to litmus paper. It may be obtained at a drug store or readily prepared at home as follows : Get a lump of lime at a grocery store. Pour on a quart of water in an open vessel and allow it to slake. When this proc- ess is completed and the lime has settled, pour off the PREPARATION OF FOOD. 235 clear liquor at the top, as this contains the potash and soda and other soluble impurities in the lime. Stir up the lime with another quart of water and pour off as be- fore; this will leave the lime quite pure. The lime may then be placed in a large bottle or quart fruit jar and this filled with water. When the lime water is clear it may be poured off into any convenient bottle for use, and more water poured on the lime. This may be repeated as long as any lime remains undissolved. 142. Syrup of lime is about thirty times as strong as lime water and can be had at any drug store. Where it is not convenient to obtain or make the lime water, one ounce of syrup of lime may be added to a quart of boiled water or one teaspoonful to four ounces. It may also be added directly to the feedings, about one or two drops to a bottle. Composition of Mixtures. 143. It is impossible to tell the exact composition of mixtures, as that will depend on the richness of the orig- inal milk, but the range of composition will always fall within the following limits, without the solids of the diluent and the sugar. Lowest Extreme. Highest Extreme. 9 oz. Top Milk. 9 oz. Top Milk from Milk Three Per Cent. Fat. 9 oz. Top Milk from Milk Five Per Cent. Fat. Fat. Per cent. Proteids. Per cent. Sugar. Per cent. Fat. Per cent. Proteids. Per cent. O.50 Sugar Per cent. Diluted 8 times* I. IO O.38 O.50 2.00 O.50 " 7 " " 6 " " 5 " I.30 I.50 I.80 •43 •SO .60 •57 .67 .80 2.30 2.67 3.20 •57 .67 .So • 57 .67 .80 4 " 2.25 •75 1. 00 4.OO 1. 00 1. 00 " 3 " 3.OO 1. 00 i-33 5.60 i-33 1-33 * Diluted 8 times means, 1 part top milk, 7 parts diluent, etc. 236 INFANT FEEDING. Lowest Extreme. Highest Extreme. 16 oz. Top Milk. 16 oz. Top Milk from Milk Three Per Cent. Fat. 16 oz. Top Milk from Milk Five Per Cent. Fat. Fat. Per cent. Proteids. Per cent. Sugar. Per cent. Fat. Per cent. Proteids. Per cent. Sugar. Per cent. Diluted 3 times* 0.7 O.38 O.50 I. 12 O.50 O.50 " 6 " " 5 " .8 •9 1. 1 •43 •5o .60 •57 .67 .80 I.30 I.50 I. So •57 .67 .80 •57 .67 .80 " 4 " 1.4 •75 1.00 2.25 1. 00 1. 00 1.8 1. 00 i-33 3.OO i-33 i-33 ti 2 * 4 2.7 1.50 2.00 4- 50 2.00 2.00 A dextrinized gruel will contain from 0.3 to 0.5 per cent proteids, 2 to 4 per cent soluble carbohydrates, de- pending' on whether one or two heaping tablespoonfuls of cereal flour is used to the quart, which adds to the nutri- tive value of the mixture. In calculating percentages of sugar the following figures will be found exact and simple : One part sugar to twenty parts mixture adds five per cent. " " " " twenty-five " " " four " " " " thirty " " three " " " " " forty " two and a half " " " " " fifty " " " two " 144. The principle of preparing food with the dipper admits of many applications. Cragin has devised an out- fit called the " Sloane Maternity Milk Set," consisting of a measuring glass graduated for twenty ounces of food, and the author's dipper. The top milk is removed from the milk bottle and mixed. Directions for Use. Get a quart bottle of good milk and let it stand on ice or in a cool place for half an hour so that the cream will show at the top of the bottle. " Diluted S times means, i part top milk, 7 parts diluent, etc. PREPARATION OF FOOD. 237 From the upper part of the bottle are obtained two kinds of top milk: Top Milk No. /., obtained by taking ten dipperfuls from the top of the bottle, the first dipper being filled with a spoon to prevent spilling, the re- maining nine dipperfuls being taken by dipping carefully from the bottle. These ten dipperfuls are to be mixed in a clean pitcher, and from the milk thus mixed the baby's food may be prepared until it is from four to six months old. Top Milk No. II, obtained by taking sixteen dipperfuls from the top of the bottle, the first dipper being filled as before with a spoon, the remaining fifteen dipperfuls being taken by dipping carefully from the bottle. These sixteen dipperfuls are to be mixed in a clean pitcher and from the milk thus mixed the baby's food may be prepared from the age of about four months until it is a year old. In using this milk set, whatever strength of food is desired, the sugar and the lime water are always the same : one ounce of milk sugar (or one-half ounce of granulated sugar) and one ounce (one dipperful) of lime water. The quantity of food made by filling the glass once is always the same — twenty ounces. The strength of the food varies with the number of dipperfuls of top milk used. Fu;. 64. — Sloane Maternity Milk Set. 238 INFANT FEEDING. Preparation of the Food. First. Into the measuring glass pour milk sugar up to the line marked one ounce milk sugar, or granulated sugar up to the line marked one-half ounce granulated sugar. Second. Add one dipperful of lime water and mix by shaking the glass. Third. Add the required number of dipperfuls of top milk according to the age of the baby as explained below. Fourth. Fill the measuring glass up to the line marked twenty ounces of food, with water, either plain, or barley water, or oatmeal water. During the first month it is usually better to use plain water, after that barley water, or if the baby is very con- stipated oatmeal water. Strength of Food for Different Months. First day — Give no milk; put in milk sugar to mark, then fill with boiled water. Second day — Add one dipperful of top milk No. I. Third day — Add two dipperfuls of top milk No. I. Fourth day — Add three dipperfuls of top milk No. I. Fifth to tenth day — Add four dipperfuls of top milk No. I. Tenth to thirtieth day— Add five dipperfuls of top milk No. I. One month to two months — Add six dipperfuls of top milk No. I. Two months to four months — Add seven dipperfuls of top milk No. I. Four months to nine months — Add ten dipperfuls of top milk No. II. PREPARATION OF FOOD. 239 When the baby needs more than twenty ounces in the twenty-four hours, fill the measuring glass twice instead of once, before putting the food into the baby's bottle. After nine months the food is prepared by shaking the quart bottle of milk when first obtained and using the plain mixed milk. After preparing the food put it (especially in hot weather) on the stove and heat it till it simmers. It is then ready to be placed in the baby's bottles which have been thoroughly washed in hot soapsuds and rinsed. The above directions are given for an average healthy baby. A frail baby or one whose weight is below the average will need to have the strength of food increased more slowly. A very strong, healthy baby may have the strength of the food increased more rapidly. If the stronger food does not seem to agree with the baby, de- crease the number of dipperfuls of milk used. By increasing or decreasing the number of dipperfuls of milk, the food can usually be adjusted to the child's digestion. Whey and Cream Mixtures. 145. Bartley's Formula : * From one quart of milk after the cream has risen siphon off the under three-fourths (this leaves the top eight ounces in the bottle). Place the under milk that was removed in a double boiler and " add a teaspoon and a half of good essence of pepsin and warm slowly to blood heat and keep at that temperature until thoroughly curdled. Now heat with constant stirring until a thermometer dipped into the milk shows a tem- * Brooklyn Medical Journal, May, 1900. 240 INFANT FEEDING. perature of 155 F. and remove from the fire; strain, while hot, through a clean wire strainer and dissolve in the whey a heaping tablespoon of sugar of milk and the white of one egg. When cold pour the sweetened whey back into the milk bottle and mix thoroughly with the cream and top milk." " To reduce caseinogen we draw off more of the bottom milk. To increase it, draw off less. To decrease fat, dip off a part of the cream. . . . To increase the fat, add a little less than the full amount of whey after removing the curd. To increase the soluble albumins, add more white of egg. The sugar may be varied at will by adding more or less as desired." The object of heating the whey to 155 ° F. is to destroy the rennet in the essence of pepsin that causes the milk to coagulate. Otherwise the top milk would curd when mixed with the whey. Westcott * has published some elaborate formulae for calculating the percentages of the fat, caseinogen, and lactalbumin in whey and cream mixtures, and a method of preparing mixtures. The principles involved are prac- tically the same as Bartley's, except that no white of egg is used. The original object of the whey and cream mixtures was to make a substitute food that should contain the same protein ingredients as human milk, assuming these to be definite proportions of caseinogen and lactalbumin, and thereby overcome the trouble caused by the curding of cow's milk. The experiments of White and Laddt led them to report " that whey has a distinct value as a * International Clinics, October, 1900. American Journal of the Medical Sciences, October, 1901. f Philadelphia Medical Journal, February 2d, 1901. PREPARATION OF FOOD. 241 diluent in making the casein coagulum finer, but is in- ferior in this respect to barley water." Since the analyses on which these schemes of prepar- ing food are based were published, much advanced work with the proteids of the milk of different animals has been done, and it is now known that the older belief as to the composition of milks and the proportions between casein and lactalbumin has been wrong, especially in the case of woman's milk (32). In many cases whey and cream mixtures are well borne, but the proteids of whey do not seem to have as much nutritive value as the proteids of the original milk from which it was made, it having been found in experiments in feeding two hundred and fifty-eight animals during an extended period that one part of skim milk produced as much gain in weight as two parts of whey ; and slaughter tests showed the flesh of the whey-fed animals to be in- ferior to that of those fed skim milk." The great differ- ence will be seen by the following approximate comparison : Sugar and salts Total solids. 100 c.c. skim milk 200 c.c. whey 3.29 gm. 1.74 " 5.71 gm. 9.00 gm. 11.58 " 13.32 " Foods For Temporarv Use. 146. Whey. — Get some junket tablets at any grocery or drug store. Dissolve one of these in an ounce (two tablespoonfuls) of cold water and add this to a quart of fresh milk. Warm gently until a little above blood heat. When the curd has become quite solid beat up well with * Henry : " Feeds and Feeding," p. 5S6. 16 2 4 2 INFANT FEEDING. a fork and keep warm until the curds have shrunk con- siderably. Then strain off the whey and set on ice. Keeping the curd warm for ten or fifteen minutes greatly increases the yield of whey. Wine may be added as a flavoring agent if desired. 147. Peptonized Milk. Warm Process. — (1) Empty into a clean quart bottle the contents of one of Fairchild's peptonizing tubes ; (2) add four ounces (eight tablespoon- fuls) of cold water; shake, and (3) add one pint of cool fresh milk and^gain shake; (4) place the bottle in water not too hot to be uncomfortable to the hand, for ten min- utes. Then either place on ice, or boil, to prevent further digestive action. This milk is likely to taste bitter. Cold Process. — Prepare the bottle as before, but set on ice without warming. This milk is only partially pepton- ized so will not have a bitter taste. 148. Egg Water.— Beat up the white of one egg in eight ounces of cold water and add a pinch of salt. This may be flavored with a few drops of aromatic spirits of ammonia or of whiskey. Booker* has given the following formula: Egg water is made by beating the white of egg in a shallow dish, allowing it to stand for two or three hours, then pour- ing off the clear fluid, leaving the foam behind. The fluid is soluble in five parts of water. It should be diluted with a larger quantity of water when the digestion is feeble, and made palatable by the addition of sugar, salt, and a few drops of lemon juice. 149. White of Egg and Dextrinized Gj'uel. — Add to eight ounces of dextrinized wheat flour gruel (137) the * " Eleventh Annual Report of the Thomas Wilson Sanatorium for Children." PREPARATION OF FOOD. 243 white of one fresh egg, and if well borne add one to two even teaspoonfuls of granulated sugar. Composition about 2 per cent proteids and 4 to 7 per cent carbohydrates. 150. Yolk of Egg and Dextrinized Gruel.— Add to eight ounces of dextrinized wheat flour gruel (*37) the yolk of one fresh egg and if well borne one to two teaspoonfuls of granulated sugar. Composition about 1.5 per cent fat, 1.5 per cent proteids, 4 to 7 per cent carbohydrates. These egg mixtures may be heated up to 150 F. without coagulating, hence they may be given warm if desired. 151. Scraped Beef or Beef Pulp. — Get a piece of steak perfectly free from taint or sliminess, which is caused by bacterial decomposition (54) ; with a tablespoon scrape the meat until nothing but fibre remains. The pulp may be salted and broiled slightly, or fed raw (108). 152. Beef fuice. — 1. Slightly broil a thick piece of steak that is free from the slightest trace of taint or sliminess; cut in small pieces and press in a clean meat press or lemon squeezer. The yield of juice is not large. 2. Cut the meat into small squares and just cover with cold, slightly salted water, and set on ice for several hours. Then press by squeezing in a piece of cheesecloth (109). i53- Beef Tea. — -Cut a pound of lean meat into small squares and let stand in a pint of cold water for an hour. Heat to not above 160 F. and express the meat through cheesecloth. This tea will contain considerable nourish- ment. If heated higher, the proteids will coagulate. If the coagulum is fed, none of the nutritive value will be lost; if removed, the tea will simply have a flavor. The nutritive value may be greatly increased by leaving some of the meat pulp in the tea. 244 INFANT FEEDING. -154. Meat Broths. — Take one pound of lean mutton, veal, or chicken with some cracked Ipone and cut into small squares; add one pint of cold water, heat gently and allow to simmer for several hours; remove all the fat. On cooling these broths will gelatinize (m). These broths, especially when thickened by the addition of flour, are highly nutritive. 155. Milk Laboratories. — The teachings of Rotch have resulted in the establishment of the Walker-Gordon laboratories for the preparation of infant's food* The infant's food is put up as a prescription. The physician fills out the following prescription blank : The Walker-Gordon Laboratory: Per :ent. Remarks. r Fat Number of Milk sugar Albuminoids .... Amount at Total solids Wat*r 100 OO For whom ordered. Date, Signature, If the physician does not care to mention the especial percentages, he can ask for percentages which will correspond to the analysis of average human milk, and he can then vary any or all of these percentages later, according to the need of the special infant prescribed for. * These are located in Baltimore, Buffalo, Cincinnati, Cleveland, Grand Rapids, Montreal, New York, Ottawa, Pittsburg, Providence, St. Louis, Toronto, Washington, D. C, and London, England. PREPARATION OF FOOD. 245 The attendants at the laboratory make up the food by mixing the quantities of centrifugal cream (43), skimmed milk, sugar, and water necessary to produce the desired percentages. It sometimes requires considerable experi- ence to know what percentages of these ingredients a given infant can digest, and often a great deal of shifting of percentages is necessary before the proportions that agree are found. The laboratories stand ready to put up these and any other food mixtures that may be desired. Without a knowledge of dietetics a food laboratory is of little value to a physician, who must have a knowledge of the percentages required by various conditions to use this valuable agent intelligently. It would be as credit- able to send his patients to a pharmacy to find out what drugs they needed, as to send them to a food laboratory to find what particular food combination they should use. CHAPTER XXIII. SELECTION AND ADMINISTRATION OF FOOD. Infant's Stools — Stomach Capacity — Care of Nursery Utensils. 156. From the time of birth until the second set of teeth is supplied there is a gradual development of the digestive process and tract in the following order (126) : 1 st. The process of absorption. 2d. The production of a stool and emptying of the bowel. 3. The secretion of the digestive juices. 4th. The development of the stomach (by the curding of the milk). 5th. The eruption of teeth with which to prepare solid food for stomach digestion. Breast milk is the food that was intended to nourish the infant and at the same time promote this develop- ment. It is easy enough to prepare a substitute food that will contain as much nourishment as breast milk, but often such food causes digestive disturbance or fails to promote the normal development. Therefore substitute infant feeding calls for a careful study of each case to dis- cover if possible why the substitute food is not succeed- ing. Sometimes it will be found that there is a deficient flow of digestive juices ; in such cases food that can be ab- sorbed with little digestive effort is indicated. At other SELECTION OF FOOD. 247 times the intestinal digestive juices will act, but the stom- ach is at fault ; here food that can easily leave the stom- ach is indicated. Again, there may be poor absorption. As any food that is not digested or absorbed will be found in the stools, an examination of an infant's stools will often show where the trouble lies, and is absolutely necessary if intelligent feeding is to be done, as food that would be indicated with one kind of stool might only aggravate the trouble if fed to an infant passing another kind. The napkins should also be examined to see if the urine leaves any stain, as a deposit of urates shows faulty metabolism. Infant's Stools. The normal infant stool is smooth, yellow, homoge- neous, and of about the consistency of thin mush. The following may be considered abnormal types: Curdy Stools. — Curdy lumps may consist of undi- gested casein or fat. The former are hard and yellowish, while the latter are soft and smooth, like butter. Green Stools. — Stools can be considered green only when that condition is evident immediately upon their passage. They are thought to be due to a fermentation, which is doubtless the result of bacterial action. Certain drugs also produce green stools (27). Stools often be- come green a certain time after passage, caused by oxida- tion of the air. Slimy or Mucous Stools. — These are the result of ca- tarrhal inflammation. When the mucus is mixed with the fecal matter, the irritation is high up in the bowel, but when flakes or masses of mucus are passed, the trou- ble is near the outlet. 248 INFANT FEEDING. Bloody Stools.— The appearance of these stools will depend on the portion of the digestive tract that is affect- ed. Small masses of dark clotted blood mixed in with fecal matter indicate that the seat of hemorrhage is high' up, usually in the small intestine. When bright-red blood is passed, the seat of hemorrhage is low down, usu- ally a little above the anal ring. Hard masses of casein may rupture the capillaries, or a fissure or polyp may be the cause of the bleeding. The appearance of fresh, bright-red blood in stools is more alarming than danger- ous. The presence of dark clotted blood is of graver sig- nificance. Yellow, Watery Stools. — These are seen in depressed nervous conditions, especially in the hot days of summer, when the bowel is relaxed and the inhibitory fibres of the splanchnic nerve do not act to advantage. Very Foul Stools. — These are caused by decomposi- tion of the albuminoid or proteid principles of the food (54). Profuse, Colorless, Watery Stools, with little fecal mat- ter, are doubtless caused by an infective germ, akin to that of Asiatic cholera. This condition is known as cholera infantum. The fluid consists largely of serum exuded from the blood-vessels, and the infant is quickly drained as if by a hemorrhage. This is often preceded by a few foul fecal stools. It is rare to see one of these types by itself. With the exception of the last, they may be seen in all combi- nations. SELECTION OF FOOD. 249 Food for Infants with Normal Stools. 157- It is always best to begin by feeding young in- fants, every two hours, two ounces of a mixture of nine- ounce top milk with eight parts of diluent to which has been added one-twentieth sugar, as previously described ( I 39)^ and watch the effect. If this is well borne, as shown by normal stools, absence of colic, and restful sleep, feed two and one-half to three ounces of a less diluted mixture, and follow this process until the feeding mixture is one-fourth nine-ounce top milk; then substi- tute sixteen-ounce top milk (136), and use one part with two parts of diluent, and finally equal parts of this top milk and diluent. When the top milk is less than one- third of the mixture, one part of sugar to thirty parts of food should be used. By this method the infant's di- gestive tract is gradually accustomed to digest the curds of cow's milk; but not until a mixture that is one-third to one-half top milk is used does the infant get as much pro- tein as a breast-fed baby. This method of feeling the way along should also be followed when the infant is receiving part of its nourishment from the breast. The percentages of fat in the infant's food may be de- creased by diluting the top fourteen, eighteen, or twenty ounces from the bottle, instead of the top nine or six- teen ounces. It is impossible to give exact quantities to be fed at different ages. All that can be done is to start with a general idea of the quantity required by the average in- fant at various ages. Begin with a weak mixture and work up as rapidly as possible to the point of toleration 250 INFANT FEEDING. in all cases (139). The graduate that may be used for measuring food (Fig. 65) shows about the stomach capac- ity at different ages, but it should be remembered that some of the food leaves the stomach almost as soon as Fig. 65.— Approximate Stomach Capacity at Different Ages. swallowed, so the size of an infant's stomach is not neces- sarily an exact measure of the quantity of food it should have at a feeding. Few young infants will be satisfied with a feeding no larger than the capacity of the stomach as measured by filling the stomach of a cadaver with water. SELECTION OF FOOD. 251 Fig. 66. — Baby Food Warmer. No infant should be left on a mixture containing less than one-fifth top milk for any length of time unless absolutely necessary, as the protein is too low in quantity. Here dextrinized gruels are of great value as diluents, as they increase the amount of protein in the infant's food, which is of great advantage (128). 158. Before giving the infant its bottle, the food should be warmed by placing it in warm water. A very convenient " Baby Food Warmer" is shown in Fig. 66. The heater is an alcohol stove which will warm an eight-ounce feeding in from three to five minutes. It is small enough to be carried when travelling. Remove the cotton stopper from the bottle and fit on the nipple. Pure rubber nipples should be used. These will easily stretch several inches and resume their original shape ; inferior nipples do not stretch easily. Invert the bottle and see that the hole in the nipple is large enough to allow the food to drop slowly, not run in a stream. Before feeding it is necessary to see that it is not too hot. A practical method of testing the warmth of food sug- gested by Marianna Wheeler consists in allowing a few drops to fall on the wrist. The nipple should never be put in the at- tendant's mouth. The infant should be held while nursing in as nearly the natural position as possible, and should not be allowed over twenty minutes in which to take food. 8a w Fig. 67.— Nipple. o- INFANT FEEDING. Regularity in feeding should be followed, and the hours at which feedings are to be given should be written down for the mother or nurse, as in breast feeding (114). Noth- ing but cooled boiled water should be offered between meals. It is well to remember that infants become thirsty. The infant should be weighed each week and a record kept of its weight (173). Unless there is a steady gain in weight something is wrong. If the infant shows no signs of discomfort or indigestion, use a stronger food — that is, more top milk and less diluent. If there is indigestion and colic, the food will have to be changed as described in another place (161). If the infant is restless at night or if one feeding is vomited, it is well to substitute a feeding of the diluent (133), which will give the digestive tract a rest and at the same time maintain the infant's strength. This is espe- cially beneficial in warm weather when the digestive function is depressed. When an in- fant vomits rancid curds shortly after feeding, use weaker top milk ; that is, if nine-ounce top milk causes trouble, try sixteen-ounce top milk or even plain milk (132). This reduces the quantity of fat that becomes rancid in the infant's food. Sugar ma)' also be reduced a half. 159- Pasteurization of Food. — When good fresh milk can be obtained, it is better not to pasteurize, as owing to the germicidal property of properly handled fresh milk little bacterial change will have taken place ; but when the milk is of doubtful quality and freshness, the infant's food should be pasteurized as soon as made up (140). If the Fig. 68.- Bottle Brush. SELECTION OF FOOD. 253 milk reddened test paper (139), lime water, syrup of lime, or bicarbonate of soda (133) should be added to the food after pasteurization, until the reddened paper turns blue again. The natural enzymes of milk are destroyed at about 158 F., but it is doubtful if they have any practical value as digestive aids, as it takes months for them to produce much change in the proteids of the milk outside of the digestive tract (32 B, 61). Care of Nursery Utensils. 160. After the food has been made up or the nursing bottles have been used, the dipper, measures, bottles, and anything that has had milk in should be first rinsed with cold water, then washed with hot water and soap or some of the washing powders, and a bottle brush. If hot water is used first, the milk " cooks on" the uten- sils, and it is then difficult thoroughly to clean them. Cleanliness is a very important part of infant feeding, as dirty utensils may harbor bacteria (59) that cause decompo- sition in the food and hence produce sick- ness in the infant. After washing with hot water the uten- sils should be boiled and the bottles either kept filled with water or inverted in a clean place until wanted for filling. Fig. 60. Oil Stove for Nurserv. 254 INFANT FEEDING. The nipples should be washed out and kept lying in a cup of water in which a pinch of borax or boric acid has been dissolved. To be sure of having a supply of boiling water, a gas stove or oil stove should be in every nursery outfit. Food for Infants with Colic, Persistent Vomiting, Abnormal Stools, and Evidence of General Malnutrition. 161. Colic may be caused by an excessive quantity of proteid in the food or by the infant not being kept warm enough, especially the bowels and extremities. The ex- cess of proteid in the food may be reduced by increasing the dilution. Persistent vomiting may be caused by feed- ing too great a quantity at a time ; from too much fat or cream in the food, or by poisonous products in the milk, the result of bacterial growth. Abnormal stools may con- tain curds of casein or fat, fermenting sugar, and mucus resulting from the undigested food irritating the intestine. Digestion is at a standstill and the infant is living partly on its own tissues, hence the malnutrition. As all these conditions are often seen at the same time, it is not always practical readily to discover the cause of the digestive disturbance. This belongs more to research work than to practical infant feeding. The prob- lem for the feeder is to nourish the infant and re-establish the digestive process. Here the natural order of develop- ment (156) can be followed with advantage: 1 st. If the stools show signs of fermentation or putre- faction, clear out the intestines with a mild purgative (see Summer Diarrhoea) (17°). SELECTION OF FOOD. 255 2d. Supply nourishment that will be absorbed with lit- tle digestive effort and spare the infant's tissues. 3d. When the stools become normal, gradually add food that will stimulate the flow of digestive juices and develop the functions of the stomach. 162. When milk feedings cause digestive disturbance as just described, it is best to stop them at once and feed gruels, dextrinized gruels, or egg-water (137) ; these will generally be retained and assimilated, and furnish consid- erable nourishment. When the digestive disturbance has subsided, a teaspoonful of plain milk may be added to a two-ounce feeding and the quantity gradually increased and sugar added as fast as the infant's digestion will per- mit. In this class of cases the addition of lime water or syrup of lime until the food is alkaline to litmus paper may be beneficial ; one part of lime water to twenty parts of food is often used. It should be remembered that the syrup of lime is about thirty times as strong as lime water; hence one teaspoonful of syrup of lime equals about four ounces of lime water. 163. Occasionally infants will be met who cannot di- gest the casein of cow's milk without constant difficulty and distress. The shifting of percentages or altering the diluent appears to make little difference in these cases, as the infant continues to fret and to show a stationary or los- ing weight. This may be the culmination of many at- tacks of indigestion, or sometimes it seems to be sort of gouty or lithaemic heritage, perhaps coming directly from the parents, and showing itself in such a form at this early age. After a fair and intelligent trial of ordinary cow's milk has proved unsuccessful, it is best to put the 256 INFANT FEEDING. infant on condensed milk. The process used in condens- ing appears to produce a change in the casein that makes it easier of assimilation in this class of cases. Fresh con- densed milk is preferable, but when this cannot be ob- tained the best brands of sweetened condensed milk may be used. Sometimes it is necessary to use as little as one teaspoonful to four ounces of plain or dextrinized gruel (137) at the start. If this is well borne the quantity of condensed milk should be rapidly increased. After the dilution has reached one to fifteen, equal parts of con- densed milk, and cream removed from a bottle of milk, and mixed, should be used for dilution, which may be re- duced gradually to one to five or six parts of diluent (com- position about two to three per cent fat, one to one and one-half per cent proteid, six to eight per cent sugar). 164. When only small quantities of food can be di- gested, one teaspoonful of beef juice (152) may be added to a two-ounce feeding. This is slightly nourishing and acts as a digestive stimulant (13). Occasionally when highly diluted milk is not well digested a much smaller quantity of more concentrated milk food will be re- tained and digested, or peptonized milk (*47) may succeed. When milk of any kind is not tolerated, white of egg and dextrinized gruel or yolk of egg with the same (149) may be tried. Occasionally dextrinized gruel will not be tolerated. Then resort may be had to whey, meat broths, or white of egg in water (148), getting back to milk feed- ings as soon as possible, always bearing in mind that the aim is to have the infant ultimately take between three and five per cent of fat, one and two per cent of proteids SELECTION OF FOOD. 257 (mixture one-third to one-half top milk), and five to eight per cent of sugar. Only general rules can be given for feeding these cases. They may be summarized as follows : 1. Maintain nutrition with any form of food that will be readily absorbed (dextrinized gruel, whey, egg mixture). 2. When the stools become normal, give food that will gradually re-establish the digestive process (add small quantity of milk). 3. Return to rnilk feeding (139) as soon as possible. 4. The fact that all the food that is utilized combines- with the oxygen of the air we breathe should not be over- looked, and hence attention should be paid to the air sup- ply as well as to the food. It should be remembered that fats retard gastric secre- tion, and that excess of sugar promotes the flow of an acid gastric juice ; therefore these ingredients should be reduced in quantity when, there is gastric disturbance. Excessive vomiting may be clue to mucus in the stomach, which may be removed by stomach washing (165) ; or to nephritis. In all forms of fevers, fats should be reduced in quantity, and easily assimilated carbohydrates in the form of dextrinized gruels (137) supplied along with milk, to reduce as much as possible the excessive destruction of protein tissues that takes place in fevers (13, 14, 19, 25). 17 CHAPTER XXIV. FEEDING BY GAVAGE— NASAL FEEDING-REC- TAL FEEDING— FEEDING PREMATURE IN- FANTS. 165. Cases are not infrequently met with in which an infant cannot or will not take sufficient nourishment by- swallowing. It will then be necessary to feed wholly or in part by the stomach tube. This proceeding is often easier than it looks ; all that is needed is a glass funnel, to which is attached a short rubber tube, and this to a soft catheter, by a short piece of glass tubing placed between the rubber tube and catheter, so that the flow of the fluid can be seen. The infant is placed in a recumbent posi- tion, with the arms bandaged to the sides of the body or fastened by a towel tightly pinned around ; an assistant steadies the head, and the tube is quickly passed through the mouth ; when it reaches the back wall of the pharynx a little force is required to deflect it downward, when it is easily passed into the stomach. In cases in which the ton- sils are much swollen, as in diphtheria, the tube may be passed through the nostril, taking care to pass the tube through the inferior meatus along the floor of the nose. It is sometimes a little more difficult to get the tube through the nose, besides being apt to cause more dis- comfort. Fluid will flow more readily when the tube is full as it passes into the stomach. Otherwise the column FEEDING BY GAVAGE. 259 Fig. 70. — Stomach Tube of air in the tube may offer some resistance to the flow of the nutrient fluid. This can be obviated by filling the tube with warm water or the fluid food, and then pinch- ing the tube just below the funnel. The fluid will then not run out of the tube, which can be passed into the stomach ; when it is in place the funnel is filled, after which the grasp on the tube is relinquished, and the fluid will easily flow into the stomach. When the tube is withdrawn, it should be pinched again to prevent drops trickling out and irri- tating the pharynx, as vomiting may be caused by such irritation. It is better to give nourishment in rather higher dilution than has been usual for the infant; often partly digested food is required when gavage is employed. The intervals between feeding should also be longer than when nourishment is given by natural means, and the stomach must not be filled too fast. Where gavage is continually employed, the stomach should be washed out every day or so with warm water before feeding, as, by removing mucus or particles of food, digestion and absorption are improved. In stomach washing, pour in water through the tube as in feeding. Then lower the funnel so that the water can siphon out of the stomach. Premature infants and atrophy cases at term may 260 INFANT FEEDING. sometimes be fed to advantage by gavage ; also harelip or cleft-palate babies, who swallow with difficulty ; and after certain operations upon the mouth. Some badly nour- ished babies absolutely refuse to take sufficient nourish- ment, which may be corrected by the use of the stomach tube. The author has seen cases in which one or two full feedings thus given was followed by the baby voluntarily taking a proper amount. In meningitis, and when there is complete or partial unconsciousness from any cause, gavage may be employed with good results. The same may be said of diphtheria accompanied by much swelling of the throat, and particularly after intubation. In the latter case, feeding by gavage should always be employed, at least for the first day or so. Later on the child may be cautiously spoon-fed with the head in a low position, and viscid substances, like condensed milk, are less apt to penetrate the tube. Finally, persistent vomiting is sometimes relieved by one or two feedings by gavage. When the stomach tube has been used for any cause, the child should be kept very quiet in a horizontal position for some time afterward ; the chance of vomiting will thus be much lessened. Rectal Feeding. 166. There is a great difference in the tolerance of the rectum to attempted feeding in the infant as in the adult. At times, such as in extreme gastric irritability or when there is local obstruction, as in diphtheria or retro- pharyngeal abscess, it is often desirable to stop for a time all nourishment by the mouth. In such cases we must bear in mind the fact that the rectum can absorb but not digest food, and that small amounts will often be retained FEEDING BY GAVAGE. 261 when larger amounts are rejected. The lower bowel must first be cleaned by a moderate injection of warm salt solution or soap suds and water. From one to two ounces of the nutrient solution may then be very slowly injected, with the buttocks slightly raised and tightly held on either side of the nozzle of the syringe. When, the nozzle is withdrawn the buttocks had better be held in close apposition for a few moments, to prevent a leaking out of part of the enema. In cases in which the rectum is intolerant, a very small amount, such as two or three drachms, will some- times be retained. The occasional addition of a fraction of a drop of deodorized tinct- ure of opium to the nutrient enema will help to quiet an over-irritated rectum, but the susceptibility of very young infants to the constitutional effects of opium must always be borne in mind. When the enem- ata are given at regular intervals, the prelim- inary washing need not be employed after FlG . 7I ._ Re ctai the first time, as this increases the irritability syrmge. of the bowel. Easily absorbable nutriment must always be employed, such as dextrinized gruel, dextrinized gruel with white of egg (*49), completely peptonized milk, or expressed beef juice and water. In cholera infantum, where the quick loss of fluid from the blood-vessels threat- ens life, the injection of a hot saline solution into the bowel sometimes affords relief. Here again a small amount is often preferable, as two or three ounces, or even half an ounce, may be retained and absorbed, when a pint may be quickly rejected. 262 INFANT FEEDING. Feeding of Premature Infants. 167. The difficulty of nourishing premature babies consists in the incomplete development of their digestive tract, and the difficulty of keeping them warm while at the same time supplying sufficient fresh air. They are exceedingly dependent upon pure air, and here it is that most incubators fail. The author has treated over fifty premature infants in incubators at the Babies' Wards of the New York Post-Graduate Hospital, but with poor re- sults. This is attributed to two factors — the absence of the breast, calling for exclusive artificial feeding ; and the delay in getting them, many of the babies being blue and cold from exposure in transporting them to the hospital when received. The author has tried all kinds of incuba- tors, and believes that only those having a fresh-air inlet connected with the outer air are safe to use. The Lyon incubator is a good example of this type. If such an in- cubator is not obtainable, an ordinary soap box may be improvised, in which the baby is placed, done up in cot- ton and surrounded by hot-water bottles. The top of the box may be partially covered with a sheet or towel, so ar- ranged as to allow free access of fresh air. The babies at first seem to do best at an average temperature varying from 85 ° to 90 F. The less the infant is disturbed the better ; at the same time proper cleanliness of the baby and incubator must be insisted on, as these infants are very vulnerable to infection of all kinds. The most im- portant factor in raising them is to secure breast milk. The milk must be drawn from the breast after the colos- trum period, the preferable time being from about eight FEEDING BY GAVAGE. 263 days to a month or so post partum. This milk must usually be diluted one-half with boiled water or sugar- water solution. The best way, in the author's experience, to administer fluid to these babies is by means of a medi- cine dropper. This must be done very slowly, drop by drop, taking care to see that the motion of swallowing is accomplished after each drop before giving another. This extra care is required from the tendency of the fluid to get into the windpipe. The author has seen a number of deaths from this cause, as shown by autopsy. When the infant is too feeble to swallow, a small catheter used as a stomach tube must be employed. It can be passed without removing the baby from the incu- bator, and does not seem to cause it much disturbance. As soon as the baby grows older and is strong enough, a small nipple may be substituted. The exact amount to be given a premature baby must depend upon the pe- riod of utero-gestation and its apparent development. In one case, weighing only two and a half pounds, a drachm every hour was given by the author, with good results. In better-favored cases, from four to eight drachms can be given every hour or two. If the infant thrives, in two or three weeks it can be given pure breast milk at two- hour intervals. Where it is impossible to get breast milk the chances of the premature baby will be very poor, but efforts must be made in the line of artificial feeding. Both the fat and proteids of cow's milk are digested with difficulty in these cases, so they must be given in very small amounts. The milk must be diluted to represent fat 1 per cent, sugar 3 per cent, proteids 0.33 per cent (one-tenth nine-ounce top milk plus one-thirtieth sugar), 264 INFANT FEEDING. of which a drachm maybe tentatively given every hour; if tolerated, gradually increase the amount. If the baby is at the eighth month, a little stronger mixture may be borne, such as fat 1.5 per cent, sugar 5 per cent, proteids 0.50 to 0.75 per cent (one-eighth to one-fifth nine-ounce top milk plus one-twenty-fifth sugar). Such a case may take from four to six drachms every hour and a half. The exact amount must depend upon the general devel- opment of the baby, bearing in mind that the stomach of the baby at term has a capacity of about an ounce. Some cases cannot digest ordinary cow's milk, and then a trial may be made of whey, expressed beef juice, egg water, or highly diluted condensed milk. In a case recently seen with Drs. Hurlburt and Sherill, of Stamford, Conn., a feeble incubator baby was successfully fed with undiluted ass' milk for about a month, gaining in weight and strength. This milk then giving out,' the baby was put on a wet-nurse and continued to thrive. CHAPTER XXV. CONSTIPATION. 168. Constipation as well as diarrhoea are relative terms, and refer more to the character than the frequency of stools. A constipated stool in an infant is usually dry and hard and voided with some difficulty. One or two such stools may be passed daily with evidence of intesti- nal discomfort, and call for dietetic treatment. In the nursing infant the mother is herself frequently consti- pated, and treatment must first be directed to her, as when she is properly regulated the infant may need no further attention. Stewed fruit, figs, prunes, oatmeal and cream, unbolted bread, and similar articles of diet may be tried with the mother, with plenty of outdoor exercise. It may be necessary to cut off milk in part, or to give it diluted with oatmeal gruel to which cream is added. A glass of cold water or Vichy immediately upon rising has a favorable effect in opening the bowel. Tea should be avoided. If these measures do not suffice, some of the tonic laxatives, such as cascara, aloin, nux vomica, and hyoscyamus may be tried. The commercial mixtures of malt extract and cascara are usually efficient and agree- able. When the mother has been regulated and the infant remains constipated, there is usually a deficiency of fat in her milk, often accompanied by a high percentage of pro- teids. If this cannot be corrected by a meat diet and 266 INFANT FEEDING. plenty of exercise (20), a little fat maybe administered to the baby just after nursing. A small teaspoonful of cream two or three times daily given in this way may correct the infant's constipation; a half-teaspoonful of sweet oil will also serve the same purpose. The efficacy of the oil is sometimes increased by combining with it a little sugar and water, a small lump of loaf sugar being dissolved in a teaspoonful of water and given with the oil. A half teaspoonful of cod-liver oil may also be employed in the same way. The nursing baby may be constipated from the moth- er's milk being deficient in both fats and proteids, or from an insufficient quantity of it. If efforts to correct this condition fail, it may be necessary to supplement the breast by the bottle in order to increase the volume of the stool (27) and thus relieve the constipation. As a rule, bottle-fed babies are more apt to suffer from constipation than those on the breast. In the former cases the condi- tion may be corrected by increasing the fat in the feeding mixture. According to the dilution often recommended for young babies, the fat barely reaches two per cent when poor milk is used in making the mixture. By using less diluent or a richer top milk (132), we may run the fat up to three per cent and thereby improve nutrition as well as relieve constipation. During the first six months or so of the first year the baby usually thrives best on a mixture containing three per cent fat and one per cent milk proteids, while later in the year four per cent fat and one and one-half to two per cent milk proteids are indicated (143). The neglect to administer percentages suitable to the age and condition of the infant is responsible for a CONSTIPATION. 267 good deal of constipation, a habit it is sometimes difficult to correct even when the cause is removed. A change in the diluent employed will sometimes be necessary; if gru- els are used, oatmeal is more laxative than barley or wheat flour. Infants of a year old may be given chicken tea, which is somewhat laxative, and beef tea may have the same effect ; expressed beef juice sometimes favors an action of the bowels. A teaspoonful to a tablespoon- ful of orange juice given in the morning often has a laxa- tive action upon the infant. The free use of water, be- tween nursings or feedings, tends to prevent too great consistency of the stools, one of the common accompani- ments of constipation. For children of two or three years, fresh fruit, such as apples, peaches, and oranges, may be given in the morn- ing; stewed fruits of all kinds are allowable, and dried fruits, such as prunes, figs, and dates, often do good ser- vice. The following method of treating prunes, given the author by Dr. Cauldwell, has often produced favorable results: Fill a preserve jar one-half or three-quarters full of fresh California prunes, and pour in boiling hot water to fill the jar; next close the jar and stand in a warm place for six or eight hours. During this time the prunes become full and swollen and the pulp is very soft. The water is then drained off and the prunes are spread on a plate so that the skins may dry quickly. They are now ready to eat ; split open and use the pulp only. Give the pulp of three to six prunes before breakfast each morning with a glass of cold water. The laxative effect of the prunes is thus much enchanced, and they are usually readily taken in this form by children. 268 INFANT FEEDING. Crandall has stated that for constipated babies it is a good plan to give prunes that have been boiled with a few senna leaves. The following " Fruit Tablets " are agreeable and effi- cacious: Take four ounces each of raisins, figs, and dates, and two ounces of ground senna leaves; remove the seeds from the raisins and dates, and finely chop the fruit; then mix on a table, adding the senna to the chopped fruit little by little, putting in sherry enough to make a paste ; roll into a mass half an inch thick, and cut into half inch squares; place the tablets between sheets of paraffin paper in a box. One or two of these tablets may be given at night and repeated in the morning if neces- sary to get the result. It may be desirable to curtail the milk in cases of ob- stinate constipation or to add cream to what is taken. The coarse cereals, such as oatmeal, unbolted bread, and all the green vegetables, may be given at two years. These foods, by their saline and fibrous contents, have a stimulating effect upon the mucous and muscular coat- ings of the intestine, and increase the quantity of fecal matter (27). Very often the trouble consists in a sluggish action of the unstriped muscular fibres of the bowel, which suit- able diet is not sufficient to correct. Deep massage of the bowel, beginning at the right iliac fossa and extending around the course of the large intestine, may aid muscu- lar action if thoroughly performed twice daily. The use of suppositories and injections also stimulates the muscles to more vigorous action. For occasional use, glycerin suppositories are very efficient, but if employed too fre- CONSTIPATION. 269 quently are apt to irritate the rectum. For continued use, gluten or soap suppositories serve best. The fault in constipation of young infants is often at the lower end of the large intestine. Owing to the length of the sigmoid flexure during infancy, this part of the bowel is sharply curved, with a resulting tendency to retard the descent of fecal matter just above the outlet of the bowel. A bland suppository, or even passing the end of a finger through the anal ring, will often cause the bowel to empty itself. The passage of a healthy digested stool after such a manipulation will prove that there is no essential fault in diet or digestion, but simply a sluggishness at the end of the bowel. If fecal matter is higher up, an injection of two or three ounces of soap suds and water, salt and water, or sweet oil and water will be required for relief. In obstinate cases a teaspoonful of glycerin in an ounce of water will usually have a quick effect. A constipated infant should be constantly observed and treated until the condition is relieved, as most of the chronic cases in later life have their beginnings in early life. No structure of the body is more amenable to habit than the bowel ; hence the importance of starting right. As soon as the baby can stand, it should be placed upon the chair or chamber at regular intervals. Yale has called attention to the importance of placing the child upon a low seat with the feet upon the floor, as it can then strain to better advantage. CHAPTER XXVI. SUMMER DIARRHOEA. 169. The cause of the diarrhceal diseases of infancy so common during the summer months is not positively known, though there can be little doubt that they are of bacterial origin. Just where the bacterial infection origi- nally takes place is hard to tell, although in many cases it is undoubtedly local. It has been generally believed in the past that the high temperature of the summer months was the cause of the diarrhceal epidemics. Heat does play an important part, especially in depressing the diges- tive function, but in the summer of 1901, which was an exceptionally hot one, the number of deaths from diar- rhceal diseases of infants throughout New York State, outside of the district including Greater New York and its suburbs, was only a little over half of that of the pre- vious summer, which was not so hot. The amount of rainfall also seems to have little or no effect on the num- ber of deaths from diarrhceal diseases of infancy. The milk supply has come in for its share of condem- nation as the principal cause of diarrhceal diseases; un- doubtedly the milk supply is a prominent factor, but there must be still other sources of infection, as breast-fed infants are sometimes attacked. If the milk supply was the exclusive cause of the dis- ease, there should be a larger proportionate number of SUMMER DIARRHCEA. 271 deaths in cities like New York, whose milk is twenty- four to forty-eight hours old when received, than in the country where the milk is produced. New York's milk supply is drawn from a wide range of country, but it is found on examining the death statistics that in some years there is a great increase in the number of deaths in the country districts where the milk is produced, and only a slight increase in Greater New York; in other years an increase in the country and a falling off in the city is found, as will be seen by the following figures obtained from the New York State Board of Health : Deaths from Acute Diarrhceal Diseases, May ist to November ist, Inclusive. Country districts. . Greater New York and suburbs .... 2,550 5,943 2,721 3,046 5,477 5,244 2,727 5,559 1896. 3,039 4,908 1897. 2,086 4,340 2,833 4,868 1899. I 1900. 1 2,187 3,202 3,557 3,867 1,89s 6,115 It is improbable that there is enough variation in the methods of handling milk from year to year to account for this fluctuation in the number of deaths. There must be some local infection. In 1901 the Borough of Manhattan of the city of New York was torn up from one end to the other for the purpose of building a subway. Sewers were opened and changed, and dust was every- where. In the country districts, where the milk was pro- duced, there was a large falling off" in the number of deaths from diarrhceal diseases, as previously mentioned, while in the district which included Manhattan the num- ber of deaths was almost double that of the previous year. It is evident that there must have been a local in- fection that caused this (62). 272 INFANT FEEDING. At the Wisconsin Experiment Station there has been worked out what is known as a curd test, by which the Z*^\ - ■■ . K i 'r-.m: > .9 ; i ■_ - ■ -' -iL^^Bl Fig. 72. — Rennet Curd of Milk when Lactic Bacteria Predominate. (Russell.) character of the bacterial changes in the milk may be de- termined and the source of the infection located. A sample of milk is curded by rennet, and the whey which contains most of the sugar of the milk drained off ; the curd is then kept at a temperature of about ioo : F. for several hours. Fig. 73. — Rennet Curd of Milk when Gas-Producing Bacteria Predominate. (Russell.) The normal fermentation of milk is souring, in which the sugar is changed into lactic acid by lactic bacteria; SUMMER DIARRHCEA. 273 when this change takes place the curd becomes firm and uniform in texture. However, if decomposition or other kinds of bacteria that attack proteids (54) are present, they find favorable conditions for growth in the curd which contains little sugar, and soon outstrip the lactic bacteria in growth (52) . Their presence is shown by the production of gas, which causes the curds to rise like bread dough, or in foul offensive odors resulting from the decomposition of the proteid of the curd. Both of these abnormal fermentations are very com- mon in milk during July and August, the months in which there is generally the greatest number of deaths from diarrhceal diseases. At cheese factories these bacterial changes are partic- ularly troublesome, and a great deal of time and study has been devoted to locating the source of the infection. The curd test has proved to be valuable for this purpose. By making a curd from the milk of each farmer and re- jecting the milk that produces gassy or foul curds, it has been possible to overcome the trouble. By following this same method with the milk of each cow, it has been pos- sible to discover the infectious material, which is almost invariably dust or filth. It has been found that no mat- ter how much care has been devoted to producing the milk, if it becomes slightly infected with dust or filthy water that contains these bacteria, they will rapidly grow and elaborate their characteristic products. In cases of summer diarrhoea there is generally a great deal of gas formed in the intestine, and many thin, sour stools containing undigested curds of milk are passed. In some instances the stools which contain undigested 274 INFANT FEEDING. curds are few but very foul and offensive, indicating a decomposition of proteids. Here are seen all the changes that result from dust and filth infecting milk. For this reason not only must care be exercised in the production of milk at the farm, but it should not be opened until delivered to the family ; and in the family care should be used to keep all utensils absolutely clean. Pasteurizing the food is one step toward preventing the growth of these bacteria ; but, if they gain access to pas- teurized food or milk, they grow even better than in fresh milk. Koplik has called attention to this question and to the necessity of the mother or nurse carefully washing her hands after changing an infant's diapers, as she may easily infect the nipple or the food in this manner. The soiled napkins should be immediately placed in a satu- rated solution of chloride of lime and allowed to soak be- fore being washed. There can be little error in concluding that contami- nation at the farm is an important factor in infecting the milk; also that dust, contaminated water, soiled hands, and possibly flies at the home are also dangerous. The greater or less infection of the milk from these sources after leaving the farm is the probable cause of the varia- tion in deaths from diarrhceal diseases from year to year in city and country. Nature of Summer Diarrhcea. 170. There seem to be bacteria present in the diges- tive tract at all times, but their growth is retarded or at least not harmful when digestion proceeds normally. During the heated term all the vital functions are de- SUMMER DIARRHCEA. 275 pressed and digestion proceeds slowly. The milk curds in the stomach normally, and the whey containing the sugar is expressed (37)- If fermentation instead of di- gestion takes place, the lactic bacteria have a free field in the whey, and the putrefactive or gas-producing bacteria in the curds, where they are protected from the action of what little digestive juice is secreted. Products of pro- teid decomposition resulting from such conditions are apt to be poisonous (54), and it is not at all uncommon to see all the symptoms of toxaemia in infants and chil- dren with diarrhceal diseases, especially when the stools are offensive. Therefore these diarrhoeas should be looked upon as cases of indigestion with a digestive tract filled with fermenting and putrefying food. As previously stated (169), the cleanest milk or pas- teurized milk is quickly rendered harmful by only a slight contamination with this putrefying material ; it is there- fore worse than useless to put any more milk or other food that will putrefy into such a digestive tract as long as this putrefying material remains. It would only aggra- vate the trouble. The diarrhoea is an attempt of nature to get rid of the offending matter. The treatment of this disease consists of giving a mild purgative thoroughly to remove the putrefying intestinal contents, and then re-establishing the digestive process. To. many mothers the giving of a purgative to an infant with diarrhoea seems folly, but it is absolutely essential to successful treatment, and if the mother cannot be trusted to give it, the doctor should do so himself. During an attack of summer diarrhoea the infant's food should be carefully looked after. The promptness 276 INFANT FEEDING. of recovery will depend largely on this, for as soon as the digestive process ceases, owing to the infection, the infant begins to live on its own tissues and there is a great and sudden increase of protein metabolism, as the protein is used as a fuel. In infants that have been on a diet poor in protein this is particularly disastrous, as they have little reserve protein to draw on. Such infants quickly succumb. The aim in feeding should be to sustain the infant by the use of food (i) that will not form a culture medium for putrefactive bacteria, and (2) that will prevent the abnormal destruction of protein tissue, which is especially large where there is fever. For this purpose carbohy- drates stand pre-eminent, and in the author's experience gruels, especially when dextrinized (137), are the best forms in which to give them. These contain a small quantity of protein in a form that will not easily undergo putrefaction, and enough carbohydrates in a form suitable for prompt absorption to sustain the infant and prevent its own tissues being destroyed to any extent. Much more nourishment can be given in the form of dextrinized gruels than in plain cereal waters. If any fermentation takes place in this food, poisonous products are not formed, as carbohydrates predominate, which bacteria change into lactic acid, that is not harmful. When dextrinized gruels cannot be had, egg water (148) may be used, but this supplies only about one-fourth as much nourishment as the dextrinized gruel. The products of egg metabolism, principally urea, must be excreted by the kidneys, which are often congested and irritated by the toxins absorbed from the intestinal tract ; and, in addi- tion, by the urine, which is concentrated and scanty, SUMMER DIARRHOEA. 277 owing to the large loss of fluid from the bowels. The products of carbohydrate metabolism pass off through the lungs. White of egg is a pure protein substance and should be used cautiously when the stools are foul, but may be used freely when they are very sour (5 2 ). Kerley, after studying several hundred cases of sum- mer diarrhoea, came to the conclusion that on a carbohy- drate diet there was less systemic poisoning, recovery was more prompt, and temperature lower than on a protein diet. , Treatment and Diet in Summer Diarrhoea. 171. First: Clean out the digestive tract by doses of castor oil (one teaspoonful) or divided doses of calomel (one-tenth grain every hour until one grain has been taken). If the stools are few and foul, the bowel should be irrigated with a quart of tepid salt solution (one tea- spoonful to a quart), to hasten the removal of the putrid matter. A fountain syringe with hard-rubber tube should be used, and the water allowed to flow in gently until it runs out clear. Second : Stop all milk food of any kind, and offer boiled water; if this is retained, feed the same quantity of dextrinized gruel or egg water (137) as the usual milk feeding, at two-hour intervals. Rice is one of the best cereals for this purpose, as it is absorbed almost com- pletely. Rice flour or one of the flaked-rice preparations (102) may be used in preparing the gruel, as these can be cooked in a few minutes. Barley and wheat flour come next in order. If the gruel produces sour acid stools, try egg water (148) or mutton broth (154). When the stools 278 INFANT FEEDING. become normal, a teaspoon/til of milk should be added to a feeding of the gruel, and the quantity cautiously in- creased until the usual mixture is taken. Often not a drop of milk will be tolerated for a long time. In these cases a strong dextrinized gruel may be used for nourish- ment, and to prevent the infant tiring of it, barley, rice, or wheat may be used alternately. Mutton broth (154) or beef juice (152) may be added in small quantities to act as flavoring agents and promoters of digestive secre- tion. Care must be exercised in giving meat broth or juice in these cases. Doming has called attention to severe ptomain poisoning from the use of beef juice made from tainted meat ; and in too large quantities the meat extractives (13) have a decidedly laxative effect. Drugs to be Used. — Subnitrate of bismuth is the prin- cipal one used, aside from castor oil and calomel. It should be given until the stools become black. Opium has its place, but should not be used before the intestine has been thoroughly cleared. Alcohol may be used up to the point where it can be detected in the breath in cases of great prostration, but many mothers are apt to give too much, which interferes with digestion and also throws additional strain on the kidneys in excreting it. Preventive Measures.— -Fresh air, cool sponge baths, and light diet are good preventive measures. The author often advises allowing the smaller children to play in a bathtub containing tepid water daily in hot weather. Care should be exercised in having the abdomen kept warm at night with a light flannel band when there are apt to be sudden changes of temperature, as cold may be the starting-point of summer diarrhoea. CHAPTER XXVII. DIET DURING SECOND YEAR. 172. The diet during the second year requires careful consideration, as this is a period of transition between the breast or bottle and the ordinary mixed diet of later child- hood. It is a time of rapid growth, with cutting of teeth, when new functions are inaugurated, all of which require watching. The common mistake in feeding is to allow too great a variety, thus taxing the digestive powers at a time when they can ill afford to be strained. Cow's milk must still form the basis and most abundant article of diet. The cutting of teeth indicates that the chemical por- tion of the digestive process (5) has been established and that the mechanical function (5) is being devel- oped. The infant is prepared chemically to change many of the articles of diet that the mother eats, but it cannot yet prepare them so that they will be acceptable to the digestive tract. Meat should be finely divided be- fore being swallowed, and until a full set of teeth is pro- vided for this purpose the dividing must be done by the nurse or mother. The nutriment of vegetable substances is enclosed in cellulose (10), which even the mother cannot digest except to a slight extent. Therefore vegetable food for infants must be well cooked to burst open the indiges- 2 8o INFANT FEEDING. tible cells. For this reason only tender vegetables or cereals should be used. A clear idea of the difference between vegetables in this respect may be had by tasting the tender tip of boiled asparagus and the woody butt of the stalk. All vegetable substances for infants and chil- dren should be cooked until they are as tender as aspara- gus tips. Fruits of various kinds are early allowable, such as orange juice, apple sauce or baked apple with the skin removed, stewed dried apples, and stewed prunes after the pulp has been squeezed through a sieve. These arti- cles are not only digestible, but have a favorable action on the bowels. At the end of the first year we may start with one soft, semi-solid meal during the day, this to take the place of one bottle. As the infant grows and shows an ability to digest this kind of food, a second similar meal may be substituted. A thin pap, made by soaking stale bread crumbs or zwieback in hot water and adding this to milk, affords a good beginning for spoon food. A fresh egg (113) boiled for two minutes and thoroughly stirred with bread or cracker crumbs is likewise generally relished. The cereals cooked to a jelly, salted, and covered with milk make a very good meal. From a nutritional standpoint oatmeal is to be preferred, but some infants seem to ob- ject to its taste. If when it is used there is a tendency to intestinal fermentation or irritation of the skin, it had better not be employed. The higher grade of rolled oats sold in packages should be selected, as they contain less husk, which is irritating to the intestines. While ordi- DIET DURING SECOND YEAR. 281 nary oatmeal requires many hours of cooking (102) these rolled oats can be thoroughly cooked by half an hour's boiling in a covered double boiler if plenty of water is used, so that each particle of oat becomes soaked before the boiling temperature is reached. Sometimes an infant will readily take one cereal while rejecting another, or will tire of one preparation after a certain amount of use, and hence require a change. Among the better known prepared cereals that may be used are Quaker Oats, Hornby's Steamed Cooked Oat- meal, Germea, Pettijohn's Breakfast Food, Wheatena, Whole Wheat Gluten, Pearl Hominy, Force, and Cook's Flaked Rice. Analyses of these and other cereals will be found in another place (page 165). Oatmeal is richest in fat and protein ; gluten comes next, and wheat, hominy, and rice follow in respective order. It is not too much again to mention the necessity of boiling these cereals with plenty of water. No attention should be paid to the extravagant claims made for some of the prepared foods. There is very little difference between any of them of the same class in nutritional value. None of the so-called " ready-to-serve " breakfast foods should be given to infants until they have been boiled fifteen minutes. Meat broths (in) may be started with the beginning of the second year, using preferably those made from mutton or chicken. Between eighteen months and two years the adminis- tration of small amounts of meat may usually begin; scraped beef (15 1 ), rare roast beef, broiled beefsteak, roast lamb, broiled mutton chop, white meat of chicken, 282 INFANT FEEDING. and fresh fish, boiled or broiled, may all be employed. Meat must be given rather sparingly at the beginning and always finely minced (108), the amount depending upon the outdoor life and exercise the child may be get- ting. At about the same period the following vegetables may be allowed — thoroughly baked potatoes, spinach passed through a colander, string beans, peas, asparagus tips, boiled onions, and celery stewed in milk. All vege- tables must be very thoroughly cooked to a pulpy consis- tency, in-order to soften and disintegrate the cellulose (Fig. 35) and thus render them more digestible. Sample Diet for Child of One and One-Half to Two Years. c Glass of milk ; cereal ; a thin slice of stale bread with butter or ' ( zwieback. 11 a.m . . .... Glass of milk or cup of meat broth. r Meats or fish — any mentioned in previous paragraph. Potatoes thoroughly baked or mashed — at first once or twice 2 to 3 p. M \ a week - j Any succulent pulpy vegetable, slice of bread and butter, and one of the milk puddings. ( Stale bread and milk, or cereal and milk, or slice of bread and I glass of milk ; stewed fruit. Tea or coffee should never be given. Such a dietary can be maintained from the age of two to three or four years. It is naturally only suggestive and will need modifications in individual cases, both as to the periods of time and articles of diet. At the begin- ning, most little children will require one night feeding, and then a bottle of plain or modified milk (139) can be given at 10 or 11 p.m. Much judgment is often required in starting the young child on a diet after the bottle has been partly or completely discarded. There is no objection to giving DIET DURING SECOND YEAR. 283 milk in a bottle once or twice daily until the child is three or four years old, if it prefers this way of taking it. A bottle holding ten or twelve ounces may be used, and the nipple will at least insure its being taken slowly. Som: young children will take milk in this manner while utterly refusing it when offered in a cup. By using tact in the method of giving food and employing some variety in the dietary, the baby can usually be nourished success- fully. New articles must, however, be started slowly and gradually; the danger is in giving too much, both in quantity and variety, in the period between babyhood and early childhood. PART IV. CHAPTER XXIII. GROWTH AND DEVELOPMENT OF INFANTS. 173. The best gauge of good feeding and nutrition will be a proper rate of growth and development. While ab- solute rules cannot be given for every case, there is a nor- mal ratio that, within certain limits, should be attained by the average infant. The exact ratio for each individ- ual is governed by hereditary influences determining the general framework of the body at birth, as well as by the kind of food available after birth. Some infants are born with very small bones, perhaps in this respect resembling one or both parents. The birth weight of such an infant, as well as that attained later, will be less than that of a baby having a large bony framework. Different races, as well as families, show considerable variation in this re- spect, within the limits of health. Needless alarm is sometimes excited if the physician or mother simply con- siders averages that are taken from a different class or community that do not apply particularly to the baby under consideration. In every case, however, the ex- tremely rapid growth of the infant after birth makes a careful observation of all the phenomena connected there- with not only interesting but important. 174- Of all the factors to be thus considered, weight is the most important. It is practically the most valuable, as showing whether the food has the proper nutritive in- 288 INFANT FEEDING. gradients and whether digestion and assimilation are well performing their functions. From birth on, the weight of the body must be taken and recorded at regular inter- vals, preferably once a week (128). If food is being changed to try and correct a station- ary or losing weight, the scales may be used every two or three days, but it must always be remembered that babies are apt to gain irregularly at short intervals. One day the infant may show a gain of an ounce and the next day Fig. 74. — Grocer's Scales for Weighing Infants and Children. a quarter of that amount, while doing perfectly well. Again, the weight may remain stationary for a day or so, and then jump up two ounces in twenty-four hours. The same person should do the weighing on the same scales, to insure uniformity. A grocer's scales, weighing frac- tions of an ounce, or those specially constructed for in- fants, may be used. The following chart, devised by Carr, is convenient to record the weighings. After weighing, put a dot where the line from the infant's weight crosses the line from its GROWTH OF INFANTS. 289 age in weeks. By connecting the dots, the weignt line is the result. 1 ■*" 1 1 °s 1 i ! i 1 l ! i!i to II 1 1 1 1 e §" T , . 1 III »_a 1 Mill Ml 1 s -- .... II III , III Mill 11 11 ts 1 " _ 1 Mil m III 1 1 1 i III III II a™ «_ St" 1 1 1 III £ II III Ml III 2" I. 1 LJ_L III 111 1 1 III III 1 Mill *►. in l. Ml III s_ Ml MM 1 1 1 1 1 1 1 M 1 , ; : - 1 .J.. II 1 1 IMI III Ml ! II II III Ill III 1 ■*» in 11 1 rill 111 1 1 in Kt II Ml i 1 • M Ml ! 1 1 1 I Ml Z .Mill 1 Ml : Mi ; III III || j 1 cn 0' M II I II J_ 1 II M III 1 111 II ^ 0" -r T 1 1 1 1 1 — •» . 1 ITT " I i T 1 t 1L III 1 1 I 1 en m™ i < ™- III III 1 II III 1 ■ 1 1 e- -1 1 II III 1 1 II 1 ill 00" 1 III Mil " 4, S II III 1 III II I 1 i 1 II » u - 1 III Mill 1 1 3 l\ 1 III | II W 3 . 1 1 . 1 . 1 1 | 1 1 1 1 1 £ II II 2 1 1 : 1 1 . 1 1 0" & a | - - » 1 1 L ~ 1 III «r . 'V *"* rt 1 1 ,, p 1, 1 ill V e>~ 1 1 l\l 1 1 ill **_ 1 i 1 1 *~ 00 h . *\ \ y ■ . .. T 1 III it J! M \ 1 -— .- X 1 1 II 1 11 1 1 1 M ' ' \. < t J_ MM III y ^n^sSSsji^i^s^ 5 x' ; ijr; 3? 3 -at 3 a ' 3 a? » a?«>s; *- :»» s; '"> •SQNnOd Nl XH0I3M The infant should, of course, always be weighed in the same clothing, that can then be easily deducted from the total. J 9 290 INFANT FEEDING. At birth the male infant usually weighs a little more than the female. In a series measured for the author, the males weighed from six to eight pounds, and the females from five and a half to seven pounds. During the first two months, it is considered by Rotch that the daily average gain should not fall below 20 gm. (two-thirds of an ounce). He gives the following table indicating a healthy increase in weight : Weight. Average Gain Per Day. Grams. Pounds. Grams. Ounces. At birth 3,000-4.000 6.6-S.S 20-30 I0-20 The infant should double its birth weight at five or six months, and treble it at fifteen or sixteen months. 175. The length of the new-born baby is slightly greater in the male than in the female. In a number measured for the author, the males averaged 50 cm. (19.6 inches), and the females 48.6 cm. (19.1 inches). Growth in length is extremely rapid during infancy, especially in the earlier months. It is most rapid during the first month, a little less so during the second, the rate of rapidity decreasing with each month. The following figures referring to growth in length are taken from Rotch : The average increase for the first month is about 4.5 cm. {\}{ inches); for the second month about 3.0 cm. (ij4 inches); for the third to the fifteenth month about 1 to 1.5 cm. {Yz to ?4 inch); for the first year about 20 cm. (8 inches); for the second year about 9 cm. (3^ GROWTH OF INFANTS. 291 inches); for the third year about 7.4 em. (3 inches); for the fourth and fifth years about 6.4 cm. (2^5 inches) ; for the fifth to the fourteenth year about 6 cm. (2H inches). 176. One of the best indices of proper nutrition is an easy and timely cutting of the first teeth. This process starts early in intra-uterine life and should be completed at the end of infancy. At birth, although nothing but smooth gums are to be seen, the alveolar processes enclose the twenty temporary or milk teeth in embryo. When beginning to come through the gums, they usually ap- pear in groups. The first to be cut are apt to be one or Fig. 76. — Diagram Showing Average Months for Cutting Teeth. both of the middle lower incisors, at the sixth or seventh month. The rest are gradually evolved, usually in the following order: upper central incisors, upper lateral inci- sors, four anterior molars, four canines, and finally the four posterior molars. The first dentition should be completed by the end of infancy at the age of two and a half years. There is always some variation, within the limits of health, as to the exact time of the evolution of the teeth. It may be said, however, that much delay in teething is an evidence of faulty nutrition or constitutional disease, such as rickets. Such delay must hence call for a care- 292 INFANT FEEDING. ful investigation of the food, both as to proper ingredients and adaptability for the infant's digestion. Fig. 77.— One Day Old. 177. A few pictures of normally developing infants will be shown, as affording a guide to the eye in recognizing what may be expected at various ages. Care has been Fig. 78. — Three Months taken to get these pictures in natural positions and post- ures. Just after birth, the trunk, arms, legs, and head GROWTH OF INFANTS. 293 have peculiar conformations. The body is of an elliptical shape, with the widest part at about the centre over the Fig. 79. — Six Months. liver, in the region of the lower ribs. The two ends of the ellipse, represented by the thorax and pelvis, are small Fig. 80.— Six Months. and not well developed. The arms are stronger and bet- ter developed than the legs. During intra-uterine life the 294 INFANT FEEDING. baby is placed in a sort of squatting position, with the legs drawn up and curled inward. This explains why the '■'"'' &W& ** '''$&& if K J 1 1 ■ ■H- Fig. 8i.— Twelve Months. young infant's legs are not straight, but have a decided bowing in of the tibia and fibula. The soles of the feet ■a it. ! ;1 ^'8 Ml 1 fcfc| '^^^m*^ JMt«^t j^^: ^" •'^^WfcpB6*it- JN _. * 3^5^T^^B^.^B Fig. 82.— Twelve Months. also tend to face inward. The head is larger than the chest at this time, with a very short neck, and the baby GROWTH OF INFANTS. 295 assumes a position of general flexion. The peculiarities of early infantile shape and position are well shown in the illustrations. For a time after birth the greatest relative strength is shown in the hands and arms, as one can easily verify by allowing the infant to grasp a finger and then trying to pull it away. At about three months the muscles of the Fig. 83. — Fourteen Months. neck have developed sufficiently to allow the infant to try and hold up its head in an uncertain way. At the sev- enth or eighth month the muscles of the back have become strengthened so that the baby can sit up, and shortly after this the infant maybe allowed to creep. There should be given free play for the muscles of the arms and legs from the first, as muscular and bony development is thus 296 INFANT FEEDING. Fig. 84. — Fourteen Month?. Fil.. 85. — Eighteen Months. GROWTH OF INFANTS. 297 r iG. 86. — Eighteen Months. 298 INFANT FEEDING. Fig. 88.— Rontgen Picture of an Infant at Nine Weeks. encouraged. The bones of the legs thus grow and straighten out, but this will be interfered with if the baby is made to sustain the weight of the body too soon. GROWTH OF INFANTS. 299 The average baby should not be encouraged to stand before the twelfth month ; efforts to walk may be begun from then on to the fifteenth and sixteenth month. When walking has been established the legs should be straight. The chest develops rapidly, with enlargement of the pectoral and shoulder muscles, and its circumfer- ence usually equals that of the head by the end of the first year. The Rontgen picture taken for the author by Dr. W. J. Morton shows the undeveloped condition of the bones of a young infant, and the importance of giving proper nutriment to build up these and other tissues. CHAPTER XXIX Methods and Results of Measuring Normal Infants. 178. In order to have additional and new data relative to the growth of healthy infants, a series of careful meas- urements were made for the author by Dr. A. Hrdlicka, the anthropologist, assisted by Dr. Pisek. Two hundred infants were thus examined, and the tables and deduc- tions given below are obtained solely from this work. By having one man alone, and he an expert, make all the measurements with instruments of precision, it is be- lieved that reliable statistics have been obtained. At the same time only a few measurements that would throw light upon the general development of the infant were taken, so that any careful person can make similar measure- ments for comparative purposes. Healthy children from the nurseries of the New York Infant Asylum, the New York Foundling Asylum, and the Mount Vernon Infant Asylum were used, and the author extends thanks to these institutions for the courtesies extended. The ages of the infants varied from the new-born of a few hours to those of two years. There were ninety-six males and one hundred and four females. Well-developed, children only were selected, the majority being on the breast and the remainder bottle-fed but in every instance doing well on its feeding. Any child who had been in hospital or showed signs of marasmus, rickets, or other constitu- METHODS OF MEASURING INFANTS. 301 tional disease was rejected, as the purpose was to obtain the measurements of the average healthy child at various Fig. 89. — French Calipers. ages. The instruments used for this work were a French non-stretchable tape for the circumferences, a pair of French calipers for the diameters, and a measuring board 302 INFANT FEEDING. to determine the length. The board was designed to give true results and obviate the inaccuracies obtained in the usual forms of apparatus employed. In the ordinary forms the pelvis can be tilted, as only one foot is pro- vided for by the construction. The measuring board here used consists simply of a plain board about forty inches long by eleven inches wide, with a firm upright headpiece attached at one end and a sliding footboard at the other end. On the board two engine-ruled metric scales are placed parallel to each other. Care must be taken to Fig. go. —Measuring Board. A, Sliding foot-board; B, headpiece ; C, metre scales. have the child's head well up against the headpiece and held there by an assistant, while the measurer presses down both knees, pushing the footboard close to the plantar surfaces of the feet. The infant is then removed and a reading made on the scale. The following measurements were taken: Circumference, Head -, Anteroposterior diameter, Lateral maximum diameter. Chest — circumference. Length of body. Weight of body. METHODS OF MEASURING INFANTS. 303 The relation of the weight to the length, the relation of the circumference of the head to the length, and the relation of circumference of the chest to the length were then calculated. Tables were next prepared dividing the results according to ages in weeks. The resume given below has been reduced to ages in months for the pur- pose of brevity and simplicity. The largest and smallest measurement of each group is indicated in the metric system, and in inches, and pounds and ounces. If we study the table, we find that the males weigh more than the females throughout the period of twenty- four months. In length the males also exceed the fe- males, but the difference is slight up to the twelfth month, when the males show a greater divergence. This is well shown in the relation of weight to length in the last col- umn. The circumference of the head is greater than the circumference of the chest at birth, and remains so up to the middle of the first year, when they begin to approxi- mate in size ; at the end of the first year the chest grows larger than the head. The females, it will be noticed, begin to show greater circumference of chest to head at the tenth month, which remains so throughout. The columns giving the relationship which exists between the circumference of the head and the length of body, and that of the head to the chest, will be an aid in recog- nizing abnormal cases, such as rickets or hydroceph- alus. The relations spoken of above are obtained from the measurements as follows : 1. Weight to the length. Multiply grams of weight by 100 and divide by centi- 304 INFANT FEEDING. metres of length. Example: Weight. 2, 778 gm. X 100 -f- 50 cm. length = 55.6, relation of weight to length. 2. Relation of circumference of head to length of body. Table of Measurements (Males). Males. Age Weight Length Circ. of head Circ. of chest Ratios of measurements Grains Lbs. Oz. Centi- meter In. meter In. Centi- meter In. ^ S >3 £ v ill %2j . 2 5 is - 1 day-1 month 2778 6 15 to 3912 8 9 50. 19.6 55.3 21 8 35.1 13.8 38.3 15.1 32. 12.6 36.7 14.4 91.1 95.8 65.8 72.1 63. 71.6 54.9 76.7 1-2 months 3374 7 6 to 5216 11 7 52.5 20.7 59.6 23.5 36.6 14.4 39.5 15.5 35. 13.8 38. 15. 95.6 96.3 66.1 71.6 63.8 68.3' 62.2 87.6 2-3 3459 7 9 to 5528 12 2 55.9 22. 60.8 23.9 38.9 15.3 41.2 16.2 34.9 13.7 41.2 16.2 89.7 100. 67.1 70.8 61.7 69.5 59.8 92.4 3-4 " 5018 11 to 6804 14 15 ' 59.1 23.3 63.1 24.8 40.2 15.8 44. 17.3 37.5 14.8 42. 16.5 93.3 95.5 64.9 70.7 60.4 69. 82.1 107.8 1-5 6152 13 8 to 7201 15 13 66.2 26. 66.3 26.1 41.3 16.3 42.2 16.6 41.1 16.3 43.2 17. 99.5 102.4 62.3 63.7 62.1 65.2 92.9 108.S 5-6 4990 11 9 to 7796 17 2 59. 23. 68.5 27. 40.5 16. 43.9 17.3 39.9 15.7 43.3 17. 98.5 98.9 64.1 69. 63.2 67 9 83.7 113.8 G - 7 5698 12 8 to 7995 18 64.8 25.5 68.7 27. 43.2 17. 45.3 17.8 41.2 16.2 45.2 17.8 95.4 99.8 65.3 67.5 62.6 68.2 87.9 119.1 7-8 « 4536 9 15 to 7924 17 6 59.1 23.3 70.8 27.9 40. 15.7 44.4 17.5 38. 15. 44.9 17.7 95. 102. 62.7 69.1 63.4 64.3 76.8 111.9 8-9 6804 14 15 to 8661 19 66.1 26.0 70.8 27.9 44.7 17.6 47.3 18.6 40.8 16.1 47.1 18.5 91.3 99.6 63.3 69.2 59.!. 69. 101.5 122.3 9-10 6662 15 1 to 8732 19 2 64.8 25.5 71.1 28. 42.9 16.9 46.3 18.2 42.3 16.7 46.1 18.2 98.6 99.6 65.1 68.3 64.8. 66. 102.5 122.8 10-11 6776 14 14 to 8565 18 12 64.7 25.5 79. 31. 44.8 17.6 45.5 17.9 39.2 15.4 45.3 17.8 87.5 99.6 63.6 69.5 56.3 68. 104.7 119.9 11 - 12 " 6634 14 9 to 8392 18 3 66.1 26. 69.8 27.5 44.7 17.6 45.3 17.8 43.4 17.1 45.1 17.8 97.1 99.5 64.9 67.3 64.5 68.2 99.4 120.2 12-13 " 7938 17 8 to 9157 20 .1 69.4 27.3 71.5 28.2 45.6 18. 47. 18.5 42.1 16.5 48.3 19. 92.3 102.7 63.8 66.6 60.7 67.3 114.4 1281 13 - 14 « 7258 15 15 to 8874 19 7 69.6 27.4 76. 29.9 46. 18.1 48.3 19. 42.1 16.5 47.7 18.8 91.5 98.8 63.4 67.7 60.5 64.3 104.3 121.1 20-21 ft 10093 22 2 75.7 29.8 48.1 18 9 50.1 19.7 104.2 63.5 66.2 133.3 22-23 ft 8108 18 5 to 11113 24 6 72.2 28.4 83.4 32.8 45. 17.7 47.9 18.9 43.8 17.2 51.7 20.4 97.3 107.9 57.4 62.3 60.6 61.9 112.3 133.3 23-24 n 10886 23 14 to 11113 24 6 76.4 30.1 82. 32.3 47.6 18.7 49. 19.3 50.7 19.9 50.8 20. 106.5 103.7 59.7 62.3 61.9 66.4 132.8 145.5 2-'3 years 10830 23 12 79.8 31.4 49. 19.3 49.9 19 6 101.8 61.4 62.5 135.7 Multiply circumference of head by 100 and divide by length of body. Example: 35.1 X 100 -r- 50 = 70.2. 3. Relation of circumference of chest to length of body. METHODS OF MEASURING INFANTS. 305 Multiply circumference of chest by 100 and divide by length of body. Example: 32 X 100 -r- 50 = 64.0. 4. Relation of circumference of head to circumference of chest. Table of Measurements (Females). Females Age Weight Length Circ. of head Circ. of chest Ratios of measurements '"» 5 J 3 I 6 ol 3 a a Jlf (5 J:~ ~ ~- £"! 1 day-l month 2580 to 3601 5 10 7 14 48.6 52.8 19 1 20.8 33.4 37.1 13.1 11.6 30. 35.9 11.8 14.1 89.8 96.8 66.1 72.2 61.7 69.8 53.1 71.7 1-2 months 3373 to 4678 7 6 10 4 52. 59.3 20.5 23.3 35.3 39. 13.9 15.4 32.8 39. 12.9 15.4 95.7 100. 63.6 73.2 61.5 66.8 64.9 78.9 2- 3 3799 to 6010 8 5 13 3 54.6 62. 21.5 24.4 37.3 41.1 14.8 16.2 34.8 39.8 13.7 15.7 93.3 96.8 65.8 70.1 59.7 68.9 67. 101. 3-4 " 4281 to 5698 9 C 12 8 56.3 61.9 22.2 21.4 39. 42.1 15.4 16.6 36.2 44. 14.3 17.3 92.8 104.5 64.2 72.4 61.8 71.7 75.7 ' 97.7 4-5 " 4494 to 5585 9 14 12 5 59.9 62.3 23.6 24.5 40.2 41.3 15.8 16.3 37.1 41.7 14.6 16.4 92.3 100.9 65.7 67. 60.5 66.9 75. 89.6 5-6 5500 to 6549 12 2 14 61.9 66. 1 24.4 26. 41.7 44.6 16.4 17.6 38.6 43.2 15.2 17. 92.5 90.8 65.3 67.9 59. 66.1 88.8 99.7 0-7 C634 to 7768 14 9 17 1 63.9 66. 25.2 26. 43.1 43.8 17. 17.2 39.8 43.1 15.7 17. 92.3 98.4 65.6 67.6 62.3 65.4 103.8 117.7 7-8 6577 to S700 14 7 19 3 63.2 69.9 24.9 27.5 42.7 44. 10.8 17.3 42.1 46.8 10.6 18.4 98.6 106.4 63. 68.8 66.6 70.7 101.1 125.3 3-9 7030 to 7853 15 7 17 3 65.8 68.8 25.9 27.1 42.1 46.2 16.0 18.2 41.2 43.7 16.2 17.2 97.8 94.6 63.8 67.2 01.1 66.2 104.6 115.5 9-10 " 5557 to 6804 12 3 14 15 62.9 64.4 24.8 25.4 42.4 42.8 16.7 16.9 39.3 40.8 15.5 16.1 92.7 95.3 66.5 67.2 61. 64.8 88.3 105.6 10 - 11 " 5188 to 9044 11 6 19 13 64.4 69.8 25.4 27.5 43.6 45.9 17.2 1S.1 42.5 48. 16 7 19. 97.4 104.6 64.8 70.8 63.4 69.1 80.0 129.5 11-12 " 0932 to 9299 15 3 20 6 63.7 71.3 25.1 28.1 43.7 46.3 17.2 18.2 42.8 48.3 16.9 19. 97.9 104.3 63.2 69.2 62.1 72.4 107. 134.8 12-13 6152 to 8590 13 8 18 13 62.5 71.1 25.6 28. 41.1 44. 16.2 17.3 43.1 48.1 17. 18.9 104.8 109.3 61.7 65.8 67.7 68.9 98.4 120.8 13-14 7655 to 9526 16 14 20 11 70.5 72.6 27.7 28.6 45.3 48.1 17.8 18.9 45.1 49.4 17.8 19. 99.5 102.7 63. 66.9 63.7 70. 108.6 131.2 16-17 " 7513 to 8080 16 8 17 11 69.1 72.4 27.2 28.5 44.7 45.1 17.6 17.8 45.2 47.2 17.8 18.6 101.1 104.6 61.7 65.3 02.4 68.3 103.8 110.9 17-18 " 7620 16 12 71.4 28.1 44.3 17.4 43.9 17.3 99.1 62. 61.1 106.8 19-20 " 8335 IS 3 73.9 29.1 46.3 18.2 46.6 18.3 100.7 62.7 63.1 112.8 23 - 24 " 8789 19 4 77.5 30.5 45.6 18. 47.1 18.5 103.3 58.8 60.8 113.4 Multiply circumference of head by 100 and divide by circumference of chest. Example: 32 X 100 -j- 35.1 = 91. 1. While infants at birth may vary widely in size, each 20 306 INFANT FEEDING individual should develop in proper proportion, the vari- ous parts of the body having a symmetrical relationship to one another. These tables will thus be found useful in estimating" a divergence from the normal average in any given child. Thus, for example, we have a male in- LENGTH WEIGHT LBS. 12 OZ. LENGTH NEWBORN WEIGHT 15.4 LBS. WEIGHT 18 LBS. 9 OZ. 12 MOS. Fig. 91. — Diagrams of Relative Measurements Constructed from Table. fant of five and a half months that comes for examination and to have its feedings regulated. It is determined that this infant should not weigh less than 4,990 gm., the length should be between 59.0 and 68.5 cm., the circum- ference of the head should average about 42.0 cm., the METHODS OF MEASURING INFANTS. 307 chest slightly below this figure, and the proportion of the length to the weight should not fall below 98.8. The diagrams (Figs. 91 and 92) done in scale will show to the eye the averages of the table at various ages. LENGTH 29.8 WEIGHT 22 LBS. 2 OZ. LENGTH 32.0 WEIGHT 24 LBS. 24 MOS. Fig. 92. — Diagrams of Realative Measurements Constructed from Table. CHAPTER XXX. Growth of Head. 179. In the human being the brain assumes overmas- tering importance in the scheme of evolution, hence its proper growth and development assumes relatively more importance than that of other parts of the body. The extremely rapid evolution of the brain during infancy, and the fact that the future efficiency and well-being of the individual depend so largely upon its normal and healthy growth, render a study of the infantile head of great interest. As the skull is fairly representative of the brain during the years of its first development, measure- ments taken during infancy are more instructive as to brain size and development than those taken in later years. The skull changes considerably in its proportions during the first three years of life, and then more slowly up to the end of the seventh year, when it has very nearly attained its full size. Ninety-eight cases, from birth up to two years, were carefully measured by the author, and the results are incorporated in the following table. Some of these figures are very slightly under similar measurements made by Dr. Hrdlicka in his series upon the general growth of infants. This is explained by the fact that the author made his studies upon hospital cases, where the subcutaneous tissue over the skull is apt to be somewhat atrophied. The bony configuration of the GROWTH OF HEAD. 309 'S3SB0 xis 'sjbsA OAV) O] SqjUOUl U33jq2l3 lUOJj ■]SB3jq UO OM] 'S3SB3 iqSig •(aAisnpui) sqjiioui ubsjqSp Ol 3 A ] 3 AV J Ul O J jj g vo •S3SBD xis 'sqjuoui 3A[3A\J pUB U3A9I5J •ISBSjq uo OA\J 'S3SB0 3qSp 'SqiUOUI U35 pUB 3UIJVJ u * •JSBSjq UO 3U0 S3SB3 3Ag 'sqjuoui 3q2t3 pUB U3A3g u "jsBSaq uo 3UO 'S3SB0 3UIU 'sqjuom xis pus aAijj '5SB3jq U O 3 3 J q J 'S3SB3 sum 'sqiuom anoj puB 33Jqx •JSE3jq UO U3A3S l S3SBD U33jq3i3 'sqjuoui 33jq3 0} 3U0 UIOJjJ ^o 00 •JSB3jq UO U33jqS[3 'S3SB3 AlU3A\5 'qjuoiu 3U0 01 ^33A\ 3UO UIOJ_J •JSB3jq UO \\V S3SBD 3uiu 'quiq uiojj •?]33M 3tio aspufi O 00 "3" £ 2 „ o _' "a - < J o < z, & m ~ - J3 3io INFANT FEEDING. skull, produced by the growing brain, would, however, not be affected by this circumstance. No distinction was made between the sexes. The circumference was taken by passing the tape horizontally around the head, passing over the glabella and a point just above the external occipital protuberance. When this is procured the fol- lowing data will give a very rough approximation of the volume: x : circumference : : 1350 : 50. Thus, if the circumference is 42 cm., the approximate volume will be JBrepsna £&&& '-La/nScfa. /" Fig. 93. — Outline of the Skull. 1 1 34 c.c. The naso-occipital arc was measured from the glabella to the external occipital protuberance. Before removing the tape, the three arcs composing the naso- occipital were read off — namely, the naso-bregmatic, the bregmato-lambdoid, and the lambdo-occipital arcs. These points are shown in the following outline of a skull, and are easily recognized in the infant. The bregma and lambda were previously marked with an aniline pencil, so that the readings on the tape at GROWTH OF HEAD. 311 these points could be readily made. Where the anterior fontanel was open, a line in continuation of the frontal sutures was marked. The binauricular arcs were meas- ured, in both cases, from the anterior rim of the meatus, and passing the tape respectively over the bregma and lambda. When the anterior fontanel was open, the antero-posterior and lateral diameters were taken. The cephalic, or length-breadth index, was measured by cali- pers, which were applied at the greatest biparietal and antero-posterior diameters. The formula for obtaining this index is as follows: Length : Breadth : : 100 : x. All cephalic indices falling below 78 are classed as dolicho- cephalic; from yS to 80, mesocephalic ; and above 80, brachycephalic. The facial length was measured from the root of the nose to the extremity of the chin, and, in the absence of the teeth, falls relatively considerably be low the adult. A configuration of the skull in each case was taken by carefully applying a strip of sheet-lead hori- zontally around it, just above the ear, the free ends always being on the right side for the purpose of uniformity. The tracing was then put upon a chart by running the point of a sharp pencil just inside the leac 1 . It is well to mark the centre of the lead in front, so as to be able ap- proximately to draw a median line through the configura- tion and thus detect asymmetry. It is not contended that this is an absolutely accurate method of obtaining a configuration of the skull, as the metal is so yielding that there is a possibility of its springing somewhat in trans- ferring it from the skull to the chart. With care, how- ever, it is fairly accurate, and will exhibit the general pushing out of the soft skull by the growth of the brain, 312 INFANT FEEDING. and any form of asymmetry that is at all marked. The following configurations, taken from the list, are fairly typical of the usual shaping of the skull, in a horizontal plane, at various ages during its most rapid growth. 1 80. The fetal skull is very small, and oval at an early stage, as both the sensori-motor and in- tellectual centres have not yet be- gun to grow. The former begins fig 94 .-Fetai skuii Between to develop later in intra-uterine 1 hree and hour Months. life, and the latter the last of all. This is beautifully shown in the configurations of the two fetal skulls. The first shows an oval, undeveloped brain, while the second exhibits the forcing out of the parietal bosses by the rapid evo- lution of the sensori- motor area of the brain, while the front of the skull appears station- ary, from the size of the configuration. After birth and with increase in the age of the in- fants, there is noted a gradual and steady enlargement of the great circumference of the Skull, and, from Fig. 95.— Fetal Skull, Seven Months, Showing the .I • r •■ ,■ 1 Forcing Out of the Parietal Bosses by the Develop- tniS, 01 ItS estimated men t of the Sensori-motor Area of Brain. GROWTH OF HEAD. 313 volume. The naso-occipital arc likewise increases at about the same general rate as the great circum- ference. In comparing the naso-occipital arc with the great circumference, there is an increasing difference Fig. 96.' Great circumference, 31 cm. Naso-occipital arc, 22 cm. Naso-bregmatic arc, 9 cm. Bregmato-lambdoid arc, 9 cm. Lambdo-occipital arc, 4 cm. Binauricular arc (through bregma), 22 cm. Binauricular arc (through lambda), 24 cm. Horizontal Configuration of New-Born Baby (Female), Small, but Sym- metrically Developed. Measurements. Diameters of anterior fontanel — antero-poste- rior, 5.5 cm. ; lateral, 5 cm. Cephalic index, 8-10. Facial length, 5 cm. Circumference of chest, 26.3 cm. Length of body, 46.5 cm Weight of body, 5 pounds., 314 INFANT FEEDING. as the infants grow older. Thus, in the table, the differ- ence under one week is 12.39 cm -> while at two years it is 14.58 cm. The naso-bregmatic and bregmato-lambdoid arcs are very similar in the series, but after seven months the former arc becomes slightly larger from the develop- ment of the frontal lobes of the brain. While the parie- tal bosses cover the sensory and, to a certain extent, the motor cortical areas, the bones of the forehead will indi- cate by their shape the stage of development of the fron- tal lobes, the foundation of the intellectual portion of the brain. Although no intellectual growth can be said to take place under two years, there should be an active evolution of the front of the brain, with increase of the perceptions. The first rapid growth of the brain after birth is more in bulk than in size and complexity of the convolutions. Hence in early infancy the various corti- cal centres have but a slight development and function. With proper evolution, the convolutions grow and are arranged in functional groups, which groups, by their growth, alter and modify the shape of the infantile skull. If the skull is small or improperly shaped in any part, the brain in such an area is imperfectly developing. A cer- tain amount of asymmetry, however, is found in all skulls, as in the other members of the body, and will be seen in the tracings previously shown. Older children some- times exhibit a compensatory deformity from a too early closure of some of the sutures of the infantile skull, that does not allow the expanding brain to develop in a sym- metrical manner. Such cases are not apt to exhibit ab- normality of brain function. The brain has simply pushed out at the point of least resistance. GROWTH OF HEAD. 3i5 Fig. 97.— Horizontal Configuration of Baby of Ten Months (Female). Fed on breast. Measurements. Great circumference, 44 cm. Diameters of anterior fontanel— antero-posterior, Naso-occipital arc, 29 cm. cm. ; lateral, 1 cm. Naso-bregmatic arc, 11. 5 cm. Cephalic index, n-rs. Bregmato-lambdoid arc, 12.5 cm. Facial length, 6 cm. Lambdo occipital arc, 5 cm. Circumference of chest, 43.5 cm. Binauricular arc (through bregma), 26 cm. Length of body, 68 cm. Binauricular arc (through lambda), 26.5 cm. Weight of body, 14 lbs. 13 oz. 316 INFANT FEEDING. 181. The fontanel is usually completely closed from the eighteenth to the twentieth month. As will be seen from the table, the closing" is rather slow until the twelfth month, when it proceeds much more rapidly. In all the cases examined, the fontanel had closed by the eigh- teenth month. Where the fontanel remains widely open with the increased age of the infant, there will always be marked symptoms of rickets elsewhere. Thus, in the case o'f a male infant, aged ten months, with both diameters 5 cm., the configuration showed a markedly rickety head, and the notes gave other symptoms of the disease. The facial length increases slowly in infants, as would be expected from the absence of teeth. In older babies, when dentition is completed, the length increases more rapidly. The importance of good nutrition in relation to brain growth will be appreciated from the fact that, in the cases •examined by the author, the skulls of breast-fed babies presented slightly larger measurements than those artifi- cially fed, especially when the latter were not digesting and assimilating their food well. The principle of biology, that the development of the individual reproduces, on a small scale, the development of the race, is well shown in the infant's brain. The higher centres and the centres of association are devel- oped late in the child. These are likewise the last ac- quirements of the race. The lower and more funda-= mental animal traits are transmitted by inheritance more than the higher ones. Good nutrition and good training are both required to develop the higher functions of the brain in a satisfactory manner. REFERENCES. Comparative Anatomy of the Domesticated Animals. A. Chauveau. New York, 1901. Physiology of the Domestic Animals. R. Meade .Smith. Philadelphia, 1890. The Food of Nestling Birds. S. D. Judd. U. S. Dept. Agr. Year Book, 1900. Text-Book of Physiological Chemistry. Olof Hammarsten, translated by John A. Mandel. New York, 1900. Text-Book of Physiological Botany. G. L. Goodale. New York and Chi- cago. The Soluble Ferments and Fermentation. J. Reynolds Green. Cam- bridge, 1899. Enzymes and their Applications. Jean Effront, translated by Samuel C. Prescott. New York, 1902. Experiments on the Metabolism of Matter and Energy in the Human Body. W. O. Atwater and H. C. Sherman. Washington, 1902. The Effect of Severe and Prolonged Muscular Work on Food Consump- tion, Digestion, and Metabolism. W. O. Atwater and F. G. Bene- dict, with the co-operation of A. P. Bryant, A. W. Smith, and J. F. Snell. Washington, 1902. Nutrition Investigations at the California Agricultural Experiment Sta- tion, 1896-1898. M. E. Jaffa. Washington, 1900. Nutrition Investigations among Fruitarians and Chinese at the California Agricultural Experiment Station, 1899-1901. M. E. Jaffa. Washing- ton, 1901. A Report of Investigations on the Digestibility and Nutritive Value of Bread. Charles D. Woods and L. H. Merrill. Washington, 1900. Studies in Bread and Bread-making. Harry Snyder and L. A. Voorhees. Washington, 1899. Feeds and Feeding. W. A. Henry. Madison, Wis., 1902. Principles of Nutrition and Nutritive Value of Food. W. O. Atwater. Washington, 1902. Foods: Nutritive Value and Cost. W. O. Atwater. Washington. 1S94. Food and the Principles of Dietetics. Robert Hutchinson. New York, 1901. Practical Dietetics. W. Gilman Thompson. New York, 1901. Meats : Composition and Cooking. Charles D. Woods. Washington, 1896. Food and Food Adulterants (Preserved Meats). Bull. 13, Pt. 10, Div. Chemistry, U. S. Dept. Agr. 318 REFERENCES. Food and Food Adulterants (Cereals). Bull. 13, Pt. g, Div. Chemistry, U. S. Dept. Agr. Cereal Breakfast Foods. Bull. 55, Maine Agr. Exp. Station. Beans, Peas, and other Legumes as Food. Mary Hinman Abel. Wash- ington, 1900. Value of Potatoes as Food. C. F. Langworthy. U. S. Dept. Agr. Year Book, 1900. Eggs and their Uses as Food. C. F. Langworthy. Washington, 1901. Infants' and Invalids' Foods. Bull. 59, Laboratory of the Inland Rev- enue Dept., Ottawa. The Use and Abuse of Food Preservatives. W. D. Bigelow. U. S. Dept. Agr. Year-Book, 1900. The Composition of Commercial Food Preservatives. U. S. Dept. Agr. Year Book, 1900. The Use of Borax and Boric Acid as Food Preservatives. V. C. Vaughan and W. H. Yeenboer. American Medicine, March 15, 1902. Conformation of Beef and Dairy Cattle. A. M. Soule. Washington, 1902. Some Essentials in Beef Production. F. Curtiss. Washington, 1S9S. Breeds of Dairy Cattle. H. E. Alvord. Washington, 1S99. The Dairy Herd: Its Formation and Management. H. E. Alvord. Washington, 1897. The Feeding of Farm Animals. E. W. Allen. Washington, 1897. The Source of Milk Fat. W. H. Jordan and C. G. Jenter. N. Y. Agr. Exp. Station Bull. 132. The Food Source of Milk Fat with Studies on the Nutrition of Milch- Cows. W. H. Jordan, C. G. Jenter, and F. D. Fuller. X. Y. Agr. Exp. Station Bull. 197. Testing Cows at the Farm. Wis. Exp. Station Bull. 75. Effect on Dairy Cows of Changing Milkers. Sixteenth Report Wis. Agr. Exp. Station. Effect of Unequal Intervals between Milkings. Delaware Agr. Exp. Station, Bull. 43. Variations in Milk of Individual Cows. Illinois Agr. Exp. Station Bull. 24. Food Cost of Producing Milk. New York. Agr. Exp. Station Bull. 89, new series ; 16th and 17th Reports Wisconsin Agr. Exp. Station. Dairy Development in the United States. H. E. Alvord. Sixteenth An. Report Bureau of Animal Industry, U. S. D. A. Dairy Products at the Paris Exposition of 1900. H. E. Alvord. U. S. Dept. Agr. Year Book. 1900. Milk: Its Nature and Composition. C. M. Aikman. London, 1S99. Milk and its Products. H. H. Wing. New York. 1S97. Dairy Chemistry. H. D. Richmond. Philadelphia, 1S99. REFERENCES. 319 Industrial Organic Chemistry. S. P. Sadtler. Philadelphia, 1S95. Testing Milk and Its Products. E. H. Farrington and F. W. Woll. Mad- ison, Wis., 1900. Analysis of Milk and Milk Products. Henry Leffman and William Beam. Philadelphia, 1896. Methods of Analysis of the Association of Official Agricultural Chemists, Adopted November nth, 12th, and 14th, 1898. Washington, 1S99. Provisional Methods for the Analysis of Foods Adopted by the Associa- tion of Official Agricultural Chemists, November I4th-i6th, 1901. Washington, 1902. A Comparison of Reagents for Milk Proteids with some notes on the Kjeldahl Method for Nitrogen Determination. Alfred Vivian. Six- teenth Report, Wisconsin Agr. Exp. Station. Estimation of the Total Solids in Milk from the per cent of Fat and the Specific Gravity of the Milk. S. M. Babcock. Eighth Report Wis- consin Agr. Exp. Station. Enzymes in Milk. S. M. Babcock, H. L. Russell, and Alfred Vivian. Fourteenth and Fifteenth Reports Wisconsin Agr. Exp. Station. The Action of Proteolytic Ferments on Milk with Special Reference to Galactase, the Cheese-ripening Enzyme. S. M. Babcock, H. L. Russell, A. Vivian, and E. G. Hastings. Sixteenth Report Wisconsin Agr. Exp. Station. Albumoses and Peptones in Milk and Cream. S. M. Babcock and H. L. Russell. Fourteenth Report Wisconsin Agr. Exp. Station. Acidity of Milk — Detection by Pepsin. S. M. Babcock, H. L. Russell, A. Vivian, and E. G. Hastings. Sixteenth Report Wisconsin Agr. Exp. Station. Effect of Lime on Milk. Farmers' Bull. 69 U. S. D. 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Some Points in the Chemistry of Cow's Milk with Reference to Infant Feeding ; with a description of a method of Home Modification of Cow's Milk. E. H. Bartley. Brooklyn Medical Journal, May, 1900. Scientific Modification of Milk. Thompson S. Westcott. International Clinics, October, 1900. A Method for the Differential Modification of the Proteids in Percentage Milk Mixtures. Thompson S. Westcott. The American Journal of the Medical Sciences, October, 1901. Whey and Cream Modifications in Infant Feeding. Franklin W. White and Maynard Ladd. Phila. Med. Jcur., February 2d, 1901. The Feeding Value of Whey. W. A. Henrj'. Eighth Report Wisconsin Agr. Exp. Station. The Importance of Milk Analysis in Infant Feeding. A. H. Wentworth. Boston Medical and Surgical Journal, June 26th and July 3d, 1902. A Plea for the Conservation of Breast Milk in Whole or in Part. T. S. Southworth. Medical Record, May 4th, 1901. The Modification of Breast Milk by Maternal Diet and Hygiene. T. S. Southworth. Medical Record, April 26th, 1902. The Ambulatory and Hospital Management of the Gastro-intestinal De- rangements of Infancj r . Henry Koplik. Archives of Pediatrics, May, 1900. The Treatment of Summer Diarrhoea in Infants. C. G. Kerley. Medical News, August 4th, 1900. A Study of Five Hundred and Fifty-five Cases of Summer Diarrhcea among the Out-Patient Poor. C. G. Kerley. Archives of Pediatrics, August, 1901. Pediatrics. T. M. Rotch. Philadelphia, 1896. Diseases of Infancy and Childhood. L. E. Holt. New York, 1897. Craniometry and Cephalometry in Relation to Idiocy and Imbecility. Frederick Peterson. Amer. Jour. Insanity, July, 1895. The Baby : His Care and Training. Marianna Wheeler. New York, 1901. The Destiny of Man. John Fiske. Boston, 1890. INDEX. Absorption of food, 34 Acidity of milk, 66, 135 Albumin, 12, 39 in milk, 48, 51, 71 Albuminoid, 25 Albumoses, 32 in milk, 52, 71 Animal cell, 10 Babcock milk test, 127 Baby food warmer, 251 Bacteria, 81 classification of, 82 counting, in milk, 92, 158-160 decomposition, 85, 150 differentiation of types of, 148 food of, 83 in dust, 87, 95 in manure, 86 in milk, 80, in in soil, 86 lactic, 82, 149, 272 numbers of, in certified milk, 112 numbers of, in grocery milk, 114 numbers of, in milk, in on cow's body, 89 peptonizing, 85 poisons produced by, 85, 150 rate of growth of, 83, 91, 92 Bacteriological examination of milk, 80, 140, 272 examination of milk, value of, 144 Bacteriology of milk, 80 140 Barley, 163, 174 21 Barley gruel, 229 gruel, dextrinized, 229 Beans, 165 Beef extract, 177 juice, 176, 243 pulp, 175, 243 scraped, 175, 243 tea, 178, 243 Biscuits, analyses of, 170 Bottle brush, 252 filler, 108 sterilizer, 113 Bottled milk, 108, 215 - .. milk, advantages of, 215 Bowel washing, 277 Bread, 168-170 changes of flour in making, 168 Graham, 169 temperature of baking, 170 whole wheat, 169 Breakfast foods, 165 Breast, care of, 187 feeding, 187 feeding, contraindications for, 191 pump, 192 shield, 191 Broths, chicken, mutton, and veal, 179. 244 Calipers, 301 Calorie, 200 Cane sugar, 26, 232 Carbohydrates, 26 as fuel, 39, 200 effect on -proteid metabolism, 33- 39 322 INDEX. Carbohydrates, estimation of, 27 Casein, 12, 43, 44 to albumin, ratio of, in milk, 6S Caseinogen, 4S .Cellulose, 14, 26, 30, 162 'Cereals, 162 analyses of, 165 cooking of, 163, 166 Cereo, 225 Certified milk, 105 milk, bacteria in, 112 milk, cost of producing, 113 Clarified milk, 99 Colic, 254 Colostrum, 59, 203. 204 function of, 205 Condensed milk, 77, 79, 172, 226, 256 Constipation, 265 Cooler, milk, no Crackers, analyses of, 170 Cream, 71 albuminoid, 77, 97 and milk mixtures, 213 centrifugal, 73 centrifugal, separation of pro- teids in, 76 difference between centrifugal and gravity, 75 evaporated, 77 gravity, 72, 2t6 gravity, composition of, 216 separating, 71 separator, 74 thickeners, 76 time required for, to rise, 72, 220 Creamery, 107 Curd test, 272 Decay, 85 Decomposition, 85, 150 -Development of infants, 2S7 Dextrin, 32, 35, 167, 224 Dextrinized gruels, 224, 229 gruels, advantage of, as dilu- ents, 224 Dextrinized gruels with eggs, 242 Diarrhoea, summer, 270 Diarrhoeal diseases and milk sup- ply, 143, 270 Diastase, 167, 224 Diet, balanced, 40 during second year, 279 of nursing mother, 189 selection of, 198 Digestion, chemical process of, 29 energy or labor expended in, 34 how human, differs from that of lower animals, 31 in different animals, 29 mechanical process of, 17 object of, 16 tests, 2S Digestive juices, 33 juices, secretion of, 33 tract, development of, by milk, 22, 24, 50, 203, 212, 246 tract, human, 23 tract of cow, 19 tract of dog, iS tract of horse, 21 Diluents, 223, 229 Diphtheria and milk supply, 142 Dipper for removing top milk, 228 Drugs eliminated in milk, 190 Dust, bacterial spores in, 95 Eggs, 13, 1S0 candled, 183 composition of, iSr flavor of. 182 market grades of, 1S2 preservation of, 1S3 Egg-water, 242 and dextrinized gruel, 242 Enzymes, 31 act by contact, 33 in milk, 52 of translocation, 35 Evaporated creams, 78 Excretion, 36 INDEX. 323 Excretion by kidneys, 36, 276 by lungs, 36, 277 Extract of beef, 178 Extractives, 13, 177, 278 Fats, 26 as fuel, 36, 200 as proteid sparers, 39 effect on appetite and diges- tion, 32, 34, 257 estimation of, 27 globules in milk, 63 metabolism of, 36 Fecal matter, 41, 247 matter, a secretion, 41 matter, character of, depends on food, 41 matter, color of, 42 Feeding, adult, 200 infant, 198 infant, according to stools, 246, 254 infant, artificial, 246 infant, breast, 1S7 infant, by gavage, 258 infant, general rules for, 257 infant, hours for, 188 infant, mixed, 194, 246 infant, nasal, 25S infant, percentage, method of, 210, 221, 235 infant, premature, 262 infant, rectal, 260 infant, regularity necessary in, 188 Fibrin, 39 Filtered milk, 99 Flour, baked, 16S ball, 167 ball, changes in, 16S Fontanel, 309, 316 Food, classification of, 25 function of, 36 infant, administration of, 251 infant, condensed milk as, 226, 256 Food, infant, cream and milk mix- tures as, 213 infant, effect of low protein in, 210 infant, for temporary use, 241 infant, pasteurization of, 232, 234, 252 infant, percentage composition of, 235 infant, preparation of, 227 infant, proprietary, 171 infant, selection of, 198, -207, 246 infant, sterilization of. 233 infant, top milk mixtures as, 231 infant, warming of, 251 infant, whey and cream mix- tures as, 239 methods of selecting for adults, 198 methods of selecting for adults not applicable to infants, 198 of different animals, 16, 31 Formaldehyde in milk, 97, 99 Fruit tablets, 268 Gastric juice, action on meat, 32, 176 juice, secretion of, 33, 34 Gelatin, 39, 180 Globulins, 12 Glucose, 26 Gluten, 14, 165, 169 Glycogen, 13, 35, 38 Growth, a process of cell division, 11 of infants, 287 of infant' s head, 308 Gruels, 224 dextrinized, 224, 229 dextrinized, advantages of, as diluents, 224 Hominy, analysis of, 165 324 INDEX. Ice in Chicago, 101 in London, 101 in New York, 101 in Paris, 101 Infant foods and feeding, see Foods and Feeding. rudiment of parent, 15 Junket, 20 tablets, 67, 241 Lactalbumin, 45 Lactometer, 132 Lecithin, 13, 51, 61, 212 Legal standards for milk, 134 Lime, effect on milk, 76, 223 syrup of, 235 water, 136, 223, 234 Maltose, 32, 35, 167 Massage of bowel, 26a Measurements of infants, 300, 304, 305. 307 Measuring board, 302 Meat bases, 13, 179 broths, 179, 244 extracts, 177 Meats, 175 Meconium, 41 Metabolism, 36 in adults, 36 in infants, 38 in starvation, 38 of carbohydrates, 36 of fats, 36 of proteids, 36 Milk, acidity of, 66, 135 acidity of, detection by pepsin, 66 analyses of, 47, 49. 64, 69 analysis of, 45 ass', 22, 47, 264 at Paris Exposition in 1900, 102 average, 47 bacteriology of, 80 bottled, io3, 215 Milk, certified, 105 certified, bacteria in. 112 certified, bacterial standard for, 125 certified, cost of producing. 113 clarified, 99 classification of, according to curding properties, 4S commissions, 105 commissions, regulations, 118 comparison of, 49 condensed, 74, 79, 172, 226, 256 cow's, 22, 47, 53, 59 curding of, object of, 20 difference between acid and rennet curds of, 48, 66 enzymes in, 52 fat of, 45 filtered, 99 fresh cow's, not truly acid, 66 goat's, 22, 47, 53 grocery, 106, 114 grocery, bacteria in, 114 grocery, cost of producing, 115 inspected, 122 inspected, bacteria in, 125 laboratories, 244 lecithin in, 51 legal standards for, 134 mare's, 22, 47, 53 market, 104 methods of testing, 127 microscopic appearance of, 73 mixed, of several cows, 63 mixed, of several cows, analy- ses of, 69 of different animals, 47, 49 one cow's, 61 one cow's, effect of irregular hours of milking, 65 one cow's fractional milkings, 62 one cow's, variations in, 64 pasteurized, 95, 100, 233 peptonized, 147 physiological function of, 22, 24 INDEX. 325 Milk, preservation of, 94 preservation of samples, 139 preservatives, 96, 138 production in Europe, 102 proteids of, 43, 53, 71 receiving stations, 107 sheep's, 22, 47, 53 souring of, 84 specific gravity of, 130 sterilized, 94 sterilized, detection of, 139 sugar of, 44 top, 217, 220, 22S woman's, 22, 47, 53 woman's, examination of, 194 woman's, modification of, 194 woman 2 s, ratio of fat to pro- teids in, 214 Mineral matter in food, 25, 27 matter in milk, 46, 61 matter, estimation of, 46 Nipple, 251, 253 care of. 187 shield, 191 Nitrogenous equilibrium, 37 Nucleo-albumin, 12 Nursery stove, 253 Nursing, 187 contraindications for, 191 hours for, 188, 252 wet, 192 Nursing-bottles, 232 Nutritive ratio, 201 Oatmeal, 165 gruel, 229 gruel, dextrinized, 229 Pasteurization of milk, 94, 100, 234 of milk in Europe, 96, 100, 103 Peas, 165 Peptones, 32 in milk, 52, 71 Peptonized milk, 242 Percentage feeding, 210, 222, 235 Premature infants, 262 Preservatives, food, 96 in milk, 138 Proteid, 25 Protein, 12, 25 all animals must have, 16 animals cannot elaborate, 15 decomposition of, 85 effect of diet, high and low in, 210 estimation of, 27 forms of, 12, 39 forms of, in milk, 43, 51, 53, 71 kind of, required in food, 39 metabolism of, 36 metabolism of, effect of carbo- hydrates on, 3S plants can elaborate, 15 quantity of, required in food, 40 vegetable, 14, 162 Prunes, 267 Putrefaction, 85 Rennet, 20 function of, 20, 49 Rice, 165 gruels, 229 mould, 167 Rumen, 18 Scales, grocer's, 288 Scarlet fever and milk supply, 142 Separator, cream, 74 Skull outline of infants, 310, 312. 313 Slime separator, 25 Slimy milk, 86 Sloane Maternity milk set, 236 Starch, 26, 163 bursting of grains by cooking, 166 in bread, 168 Starvation, 37 in children, 3S effect of albumen in, 39 326 INDEX. Starvation, effect of carbohydrates in, 3S effect of proteid in, 39 Sterilization of milk, 94, 234 Sterilizers, 113, 234 Stomach, capacity of infant's, 250 of different animals, 16-24 tube, 259 washing, 259 Stools, infants', 41, 247 vStreptoccoci in milk, S7, 151 Sugar, 26 cane, 26, 232 effect on digestion, 34, 257 estimation of, 47 milk, 26, 44, 232 milk, of cows not identical with human, 44 Summer diarrhoea, 270 diarrhoea and milk supply, 143, 271 Suppositories, 26S, 269 Teething, 291 Thickeners, cream, 76 Tin pudding bag, 167 Top milk, 217-220, 22S milk mixtures, 227 Tuberculin test, Sg Tuberculosis and milk supply, 86, 140 Tuberculous udder, SS Typhoid fever and milk supply, 141 Udder, cow's, 86 tuberculous, SS Urea, 36, 276 Uric acid, 36 Urine, 36, 40, 276 Utensils, seams of dairy, 90 Vegetable foods, 162 Viscogen, 76 Vomiting, 254 Weaning, 194 Weight chart, 289 infant, 2S9 Wet-nursing, 192 Wheat bread, 170 breakfast foods, 165 flour, 172 flour gruels, 229 flour gruels, dextrinized, 229 Whey, 49, 65, 69, 241 analyses of, 69 and cream mixtures, 239 to make, 241 food value of, 241