ee ee MRR eu cas Ku sR Meany Ae my hain Rican ne ty arena ea uueiineorre nie pt Cen ieae ALBERT R. MANN LIBRARY AT CORNELL UNIVERSITY DATE DUE Cornell University Libra text-book of general lichenology, with mann A TEXT-BOOK OF (GENERAL LICHENOLOGY, WiruH DESCRIPTIONS AND FIGURES OF THE GENERA OCCURRING IN THE NORTHEASTERN UNITED STATES. BY ALBERT SCHNEIDER, M.S., M.D., Fellow tin Botany, Columbia University, 1894-1896. BINGHAMTON, N. Y. WILLARD N. CLUTE & COMPANY. 1897. eI Rccwal USF 3 ; os 2 a : ne CopyricutT, 1897. BY WILLARD N. CLUTE & CO. (& L274, 22 j Press OF ‘Tur New Era Prinvinc CoMPANY LancasTER, Pa. TABLE OF CONTENTS. PREFACE GLOSSARY. . LITERATURE PART I. vii ~ xi Tue History, Gunekat MorPHOLOGY AND PuysioLoGy oF LICHENS. CHAPTER I. Tue History oF LICHENOLOGY. INTRODUCTION I. PERIOD: From Theophrastus (371-286 B. C.) to Tournefort (1694) II. Per1op: From Tournefort (1694) to Micheli (1729) IlI. Perrop: From Micheli (1729) to Weber (1779) IV. Perrop: From Weber (1779) to Wallroth and Meyer (1825) V. Periop: From Wallroth and Meyer (1825) to Schwendener (1868) . VI. Perrop: From Schwendener (1868) to Reinke (1894) VII. Perrop: From Reinke (1894) to the close of 1896 CHAPTER II. SYMBIOSIS. INTRODUCTION . : 31 Bs I. ANTAGONISTIC Suuurpai (Para- Le 2. sitism).. . 31 Asraponistie Symbloste. of Fungi with Lichens 32 Antagonistic Symbiosis of Lichens with Lichens (Syn- trophy) ie» el BB Antagonistic Symbiosis of Lichens with Mosses II. Nurricism. III. gels tar Shannen CHAPTER III. - Mutualism . , 2 3. Individualism ; Contingent Mutualism . THe GENERAL MORPHOLOGY AND PuysIoLoGy oF LICHENS. 7. The Cilia REPRODUCTIVE AND PROPAGA- INTRO DUCTION 40 I. ORGANS OF peeaaenes 40 1. The Thallus . 40 np (a) Tegmentary Layer (pani, (b) The Upper Cortical Layer. (c) The Algal Layer (Gontdial Layer). {(d) The Medullary Layer. (e) The Lower Cortical Layer. . Types of Thalli. .. - 47 (a) The Crustaceous Type. (6) The Foliose Type. (c) The Fruticose Type. . Breathing Pores. ae 52 . The Cyphellae . 52 . The Cephalodia.. . 2. . . 55 (a) Ectotrophic Cephalodia. (8) Endotrophic Cephalodia. . The Rhizoids.. ... 59 II. 4 w TIVE ORGANS. . The Apothecia . (a) The Epithecium, (4) The Thecium, (c) The Hypothectum, ‘d) The Upper Algal Layer. (e) The Medullary Layer. (Sf) The Lower Algal Layer. (g) The Cortical Layer. - Types of Apothecia. (a) The Fungal Type. (5) The Thalline Type. . The Soredia . : .. The Thecial Algae (Hymenial Gonidia) .. Now HATO 24. 28 34 35 36 37 39 62 62 66 67 68 CHAPTER IV. THE GrowTH, MECHANICS AND CHEMISTRY OF LICHENS. INTRODUCTION I. THE GROWTH OF THE THALLus. 71 . The Protothallus (Hypothal- va Promycelium ) 71 2. Development of the Thallus. 72 (a) Horizontal Growth. (0) Vertical Growth. (c) Intercalary Growth. II. GRowTH OF THE APOTHECIA 95 III. THe DEVELOPMENT AND STRUC- TURE OF THE SPORES Vi] IV. GROWTH OF THE ALGAE. . 78 V. THE SPERMAGONIA 80 VI. MECHANICAL ADAPTATIONS. . 81 VII. THE CHEMISTRY OF LICHENS 84 CHAPTER V. REPRODUCTION AND PROPAGATION OF LICHENS. I. THE SPORES... 87 . The Hjecelon atid “‘Disieian- tion of Spores . . 87 . The Germination of apie 89 3- Spores as Organs of Repro- duction . . 90 II. THe SorEDIA AS PROPAGATIVE ORGANS. . g2 III. VEGETATIVE PROPAGATION . 93 IV. LiFe-PERIOD oF LICHENS 94 CHAPTER VI. THE POLYPHYLOGENY OF LICHENS. INTRODUCTION. . ee a 96 2. Chroolepus ( Trentopohlia ) I. THE FuNGAL Types . . : 97 umbrina . 100 a. The Pezizaceae . . 98 3. Pleurococcus vulgaris . 100 2. The Patellariaceae . . . 98 4. Dactylcococus infusionum 100 3. The Phacidiaceae . 98 5. Nostoc commune. . 100 4. The Stictidaceae . 99 6. Rivularia nitida 101 5. The Sphaeriaceae 99 4. Polycoccus punctiformis 101 II. Tue Arca Types... 99 8. Gloeocapsa polydermatica 101 1. Cystococcus humicola .. 99 g. Sirosiphon pulvinatus . . 101 PART II. THE CLASIFICATION AND SpEecIAL MorpuHoiocy oF LicHEns. CHAPTER I. A SYSTEM OF CLASSIFICATION. I. InTRoDUcToRY CONSIDERATIONS.102 II. CuemicaL REACTIONS 106 CHAPTER II. DESCRIPTIONS OF THE FAMILIES AND GENERA. INTRODUCTION. . . i 2 9 508 3. Calicium . ‘i 114 GENERAL Description OF THE 4. Cyphelium 115 PLATES . 110 5. Acolium.. . 115 KEY TO THE FAMILIES . 109 6. Sphaerophorus. . 117 I. CALICIACEAE .. 110 TI. CLADONIACEAE .,. . 118 1. Mycocalicium... . 112 1. Baeomyces. . 120 2. Coniocybe... . . 112 2. Pilophoron.. ... .. 122 3. Stereocaulon . . 4. Cladonia.. 5. Thamnolia.. . IU. LEcIDEACEAE . 1. Biatorella . . . Biatorina . Biatora. . . Bilimbia. . Bacidia .. . Lecidea. . . Celidiopsis. . . Buelliopsis . Buellia . Catillaria . DIAN EW wow 4 O00 12. Lopadium. . 13. Gyalecta.. 14. Psora 15. Gyrophora . 16. Umbilicaria IV. GRAPHIDACEAE . . Hazslinskya . . Opegrapha . Graphis .. . Xylographa . Arthonia . Mycoporum . Arthothelium HYSCIACEAE . Rinodina . Placodium . . Pyxine . Physcia . 5. Theloschistes VI. PARMELIACEAE. 1. Urceolaria BWP HM ANEW De 2. Haematomma 3. Lecanora LEPRARIACEAE—Pseudolichenes .. 1. Lepra . 2. Amphiloma . THE CONTINENTAL GENERAL INDEX. . . . Megalospora . RANGE , 124 2125 127 128 130 131 132 . 133 134 135 135 136 136 - 137 - 137 . 138 139 - 140 141 » 143 » 144 » 145 146 146 147 148 149 150 I51 152 154 2 ASS . 156 158 159 . 161 . 162 164 VIII. Parmelia . Cetraria . Evernia . g. Ramalina 10. Alectoria 11. Bryopogon. . 12. Usnea . VII. VERRUCARIACEAE... . 1. Trypethelium . Pyrenula. . Conotrema. . Thelotrema. Gyrostomum . Verrucaria . . Pertusaria . Dermatocarpon Endocarpon OLLEMACEAE 1. Collema .. Leptogium 3. Mallotium .. 4. Hydrothyria . . IX. PANNARIACEAE .. 1. Ephebe . Lecothecium . Lichina. Omphalaria . Polychidium Psoroma . Heppia Pannaria . Peltigera . Solorina . Nephromium . Stictina . 13. Sticta . 3 4+ 5 6. 7 8. 9. Cc PETAR EES HoH ow NH O CHAPTER III. 1 DE . 217 . 218 OF . Acarospora ... . Speerschneidera . . 213 - 215 165 . 166 167 . 169 170 192 . 173 175 176 177 179 . 180 181 . 182 184 185 186 . 188 189 . QI 193 » 194 195 196 197 » 199 . 200 . 201 - 203 . 204 . 205 . 206 - 207 . 209 . 210 THE GENERA OCCURRING IN THE NORTHEASTERN UNITED STATES 219 «223 vil PREFACE. This work is primarily intended as a text-book for the use ot students in colleges and universities, but will also be found useful to the specialist. Although the title designates it as a text-book of general lichenology, the discussion of the Basidiolichenes and more or less problematical Gasterolichenes has been omitted, since these orders are not represented in the northeastern United States. The systematic arrangement of the families and genera here pro- posed is by no means perfect, yet it is hoped that some progress has been made toward establishing a natural system. The fact that most arrangements heretofore proposed had little scientific basis is due‘to the lack of knowledge of the morphology and physiology ot these plants. Even now our methods of physiological investigation are too imperfect to allow us to obtain any satisfactory data in regard to the life-history of the individual lichen. Until our methods of investigation are more perfect, all systems of classification must of necessity be more or less artificial and subject to changes. In lichenology the conception of genus and species is vague and uncertain. This is the chief reason why every lichenographer has introduced or sought to introduce a new system, and as a result we have about as many systems as there are authors. Within compara- tively recent years various investigators have studied lichens from a scientific point of view, especially from the standpoint of morphol- ogy. Of these morphologists may be mentioned Hedlund, Lindau, Minks, Reinke, Schwendener, Zahlbruckne and Zukal. Among those who have studied lichens from a physiological standpoint Bon- nier and Jumelle deserve special mention. The arrangement of families and genera here adopted is based upon morphological data and is in accordance with the results of recent investigations. In agreement with Reinke, lichens are treated as a distinct class, coequal in systematic importance with the fungi and algae. The present conception of the class Lichenes is, however, essentially differ- vill ent from that of the older authors, such as Tuckerman and others, being in a great measure the outcome of recent investigations in symbiosis. For this reason it was thought advisable to include a chapter on the more common phenomena of symbiosis, which, it is hoped, will enable the student to obtain a better knowledge of the true nature of lichens. Part II. treats of the special morphology of the families and genera of lichens occurring in the northeastern United States. The drawings (with the exception of Plate 5) were made by Mr. F. Emil, under the author’s supervision. Duly considering the diffi- culties usually encountered in making drawings of this kind it is be- lieved that they give a fairly accurate presentation of the histological characters of the genera occurring in the territory. It is hoped that this work will act as an incentive toward leading others to the more scientific methods of studying this interesting group of plants. With Reinke, I wish to emphasize the necessity for studying more carefully the polyphyletic origin and relationship of the various lichen groups. This will, no doubt, lead to a more accurate delimitation of the families, and incidentally also to a more accurate knowledge of the phylogeny of other plants. CoLumBIA UNIVERSITY, May 31, 1897. ix * GLOSSARY. Antagonistic symbiosis, a form of symbiosis in which one of the sym- bionts is benefited at the expense of the other; usually known as parasitism. Apothecium (Apothecia), the spore-bearing structure of lichens, in- cluding epithecium, thecium, hypothecium and exciple. Areolate, a term referring to a crustaceous thallus which is marked off into minute, usually polygonal areas. Breathing pores, intercellular canals in the cortical layers leading from the interior of the thallus to the exterior. Cephalodium (Cephalodia), usually a globular, flattened or irregular outgrowth from the upper or lower surface of the thallus, induced by for- eign algae and bearing them. Contingent symbiosis, a form of symbiosis which is not constant in its occurrence. (Incipient symbiosis. Raumparasitismus. ) Cortex, see Cortical. Cortical layers, pseudo-parenchymatous tissue (upper and lower) of the thallus of the higher lichens. Crustaceous thallus, a firmly adherent thallus of lichens devoid of distinctly cortical layers. Cuticle, see Epidermis. Cyphella (Cyphellae), a pit or depression in the under surface of the thallus of most Stictei (.S¢/cfa and S¢éctiza). They are neoformations anal- ogous to lenticels. fr Endospore, the inner coat of the spore-wall. Epidermis, the thin horizontal scaly layer on the upper surface of the higher foliose lichens. Epilithic, a term applied to the parts of lichens occurring on and above the surfaces of rocks. Epiphloeodal, occurring on the surface of the bark. Epispore, see Exospore. Epithecium, the upper colored structureless coating of the thecium. Exciple or Excipulum, the outer covering of the apothecium; when formed by the thallus and bearing algae it is known as thalloid exciple; when formed by the perithecitum and not bearing algae it is known as proper exciple. Exospore, the outer coat of the spore-wall. Fibril or Cilium, a slender filament, consisting of united hyphae, usually occurring on the margin of the thallus. Foliose thallus, an expanded entire or lobed thallus, having one or two cortical layers, usually attgched by rhizoids. Also known as foli- aceous or frondose thallus. 2 = NX Fruticose thallus, a thallus consisting of rounded or flattened, vertical or ascending branches. Also called fruticulose thallus. Gonidium (Gonidia), a term applied to the symbiotic algae of lichens. Granule (adj. Granulose), a minute thalloid elevation firmly adherent to the substratum, usually bearing an indistinct upper cortical layer. Hymenium, see Thecium. Hypolithic, occurring below the surfaces of rocks. Hypophloeodal, referring to that portion of the thallus or other struc- ture of lichens occurring beneath the surface of the bark. Hypothecium, the dense hypal tissue immediately below the thecium. Individualism, a form of symbiotic relationship existing between two or more organisms in which the resulting organic structure is wholly differ- ent from any of the symbionts and in which at least one of the symbionts cannot exist independently. Isidium (Isidia), a small cylindric simple or branched thalloid out- growth from the surface of the thallus. Medulla, the loose hyphal network in the interior of the thallus. Mutualism, a form of symbiosis in which the symbionts are mutually beneficial. Mycorhiza, a term applied to the symbiotic association of fungi and roots of higher plants (especially Capuléferae). Divided into endotrophic and ectotrophic mycorhiza according to whether the fungi occur within the parenchyma-cells of the root or upon their exterior. Mycodomatiae, term applied to the group of symbiotic organisms (rhizobia) which have the power of inducing tubercular neo-formations in the roots of plants. Nutricism, a form of symbiosis in which only one of the symbionts is especially benefited. Paraphysis (Paraphyses), a slender simple or more rarely branched, sterile filament among the spore-sacs. Perithecium, the hyphal tissue of the so-called Pyrenolichenes ( Ver- rucartaceae) enclosing the thecium. Phyllocladium (Phyllocladia), a small highly assimilative branch of fruticose thalli. (This term is often applied to all secondary thalli.) Podetium (Podetia), the elongated alga-bearing apothecial stalk of lichens developed from the primary thallus. (Usually applied to the ver- tical thallus of a Cladonda.) Primary thallus, aterm referring to the thallus from which the podetia develop. Pycnidium (Pycnidia), the structure upon the thallus of lichens con- taining the so-called stylospores. (Perhaps closely related to the sperma- gonium. ) ; Xi Rhizoids, special hyphal elongations from the under surface of the thal- lus which enter the substratum. Secondary thalli, thalloid outgrowths from the thallus and podetia of lichens. Sometimes also applied to the podetia of Cladouia. Seta (Setae), see Fibril. Soredium (Soredia), a minute spherical body consisting of algae en- closed by a hyphal network and having the power of developing into a new lichen. Spermagonium (Spermagonia), the structure upon the thallus con- taining the so-called sterigmata and spermatia. Spermatium (Spermatia), a spore-like body formed in the sperma- gonium. (Considered by Stahl and others as the male reproductive organ of lichens. ) Spore-sac, the closed sac-like structure in which the spores are formed. Squamule, a small entire thalloid lobe. Usually forming the transition to the typical foliose thallus. Sterigmata, the filaments of. the spermagonium bearing the spermatia. Stipe, an apothecial stalk free from algae ( Caléczaceae and Bacomyces ). Symbiosis, a contiguous association of two or more organisms ac- companied by an interchange of assimilated food-substances. Thallus (Thalli), the vegetative and assimulative portion of lichens, bearing the apothecia and soredia. Theca (Thecae), see Spore-sac. Thecium (Thecia), the layer consisting of thecae and paraphyses. Umbilicus, the single root-like attachment of certain lichen-thalli ( 7- bilicaria, Gyrophora). Verrucose, see Warty. Warty, referring to a thallus bearing numerous thalloid elevations larger than the granules. LITERATURE. The references here given are to the principal works on the mor- phology, physiology and chemistry of lichens issued since the year 1850, and terminating with the year 1896. 1. Basixorr, M. Du développement des céphalodies sur le thallus du lichen Peltigera aphthosa Hoff. Bull. Acad. Imp. Sc. St. Petersb. 24: 548-559. 1878. 2. BacuMann, E. Ueber nichtkrystallisirte Flechtenfarbstoffe. Jahrb. wiss. Bot. 21: 1-60. 1890. 3. BacHMANN, E. Der Thallus der Kalkflechten. Ber. deutsch. bot. Ges. 10: 30-37. 1892. Xil 4. Baranetzky, J. Beitrag zur Kenntniss des selbststiindigen Lebens der Flechtengonidien. Jahrb. wiss. Bot. 7: 1-17. 1869. 5. Bayruorrer, J.D. W. Einiges tiber Lichenen und deren Befruch- tung. Bern. 1851. 5a. BayruorFrer, J. D.W. Entwickelungund Befruchtung der Clado- niaceen. Frankfurt am Main. 1860. 6. Beyerinck, M. W. Culturversuche mit Zoochlorellen, Lichen- gonidien und anderen niederen Algen. Bot. Zeitung, 41: 765-768, 781- 785. 1890. 7. Bonnier, G. Culture des lichens a l’air libre et dans un milieu privé des germes. Bull. Soc. Bot. France, 33: 546-548. 1886. 8. Bonnier, G. Recherchés exprimentales sur ]a synthése des lichens dans un milieu privé des germes. Comptes rendus, 103: 942-944. 1886. g. Bonnier, G. La constitution des lichens. Journal de Botanique, r: 1-5. 1887. 10. Bonnier, G. Recherches sur la synthése des lichens. Annales des sc. nat. (VII) g: 1-34. 1889. 11. BonniER, G. Germination des lichens sur les protonémes des mousses. Rev. gen. bot. 1: 165-169. 1889. 12. BonnriER ET MANGIN. Sur les échanges gazeux entre les lichens et ’atmosphére. Bull. Soc. Bot. France, 31: 118-119. 1884. 13. Bornet, E. Recherches sur la structure de ’ &phebe pubescens Fr. Ann. sc. nat. (JIT) 18: 155-171. 1852. 14. Bornet, E. Description de trois lichens nouveaux. Mem. de la soc. de Sc. nat. de Cherbourg, 4: 231. 1856. 15. Bornet, E. Recherches sur les gonidies des lichens. Ann. sc. nat. (V) 19: 314-320. 1874. 16. BorneT, E. Deuxiéme note sur les gonidies des lichens. Ann. sc. nat. (V) 19: 316. 18474. 17. CromBiE, Rev. J. M. See KREMPELNUBER. 18. Curtiss, C. C. A contribution to the history of the formation of the lichen-thallus. Journal of the New York Microscopical Society, 10: 3. 1894. 19. DancEearpD, P. A. Recherches sur la structure des lichens. Le Botaniste, 4: 18-20. 1894. 20. DarsisHire, Kritische Bernerkungen tiber das ‘‘ Microgonidium.” Hedwigia, 34: 181-190. 1895. 21. DeBary, A. Morphologie und Physiologie der Pilze, Flechten und Myxomyceten. Leipzig, 1866. 22. DeBary, A. Ueber die Keimung einiger grosssporiger Flechten. Jahrb. wiss. Bot. 5: 201-216. 1866-1867. 23. FAMINTZIN UND BARANETzKY. Beitrag zur Entwickelungsge- Xiil schichte der Gonidien und Zoosporenbildung bei Physcta partetina D.N. Bot. Zeitung. 25: 181-190. 1867. (Preliminary report.) 24. FAMINTZIN UND BaRANETzKy. Zur Entwickelungsgeschichte der Gonidien und Zoosporenbildung der Flechten. Memoires de l’acad. de St. Petersbourg, 11: 1-9. 1868. 25. Forssert, kK. B. J. Studier 6fver cephalodierne. Bihang till k. Svenska vet. Akad. Handlinger, 8: 1. 1883. Separatabdruck, Stock- holm, 1883. 26. ForssEtt, K. B. J. Beitriige zur Kenntniss der Anatomie und Systematik der Gloeolichenen. Nova Acta Reg. Soc. Sc. Ups. 1885. 27. ForsseLyt, K. B. J. Ueber den Polymorphismus der Algen (Flechtengonidien) aus Anlass von Herrn Zukal’s Flechtenstudien und seinem Epilog dazu. Flora, 69: 49-64. 1886. 28. Frank, A. B. Ueber die biologische Verhiiltnisse des Thallus einiger Krustenflechten. Cohn’s Beitrige. Breslau. 1876. 29. Fries, T. M. Beitrag zur Kenntniss der sogenannten Cephalo- dien dei den Flechten. Flora, 4g: 17-25. 1866. 30. Furstinc. Beitriige zur Entwickelungsgeschichte der Lichenen. Bot. Zeitung, 26: 641-647, 657-665, 673-684. 1868. 31. Fonrsticx, M. Thallusbildung an den Apothecien von Peltédea aphthosa (L.) Ach. Ber. deutsch. bot. Ges. 2: 447-452. 1884. 32. Funrsttcx, M. Die Fettabscheidungen der Kalkflechten. Bei- trige ztir Wissenschaftlichen Botanik, 1: 157-220. 1895. 33. GiBELLI, G. Sugli organi reproduttori del genere I crrwcaréa Milano, 1865. 34. GIBELLI, G. Ueber die Reproductionsorgane der Gattung I erra- car¢a (tibersetzt von A. v. Krempelhuber). Flora, 4g: 65-75, 87-92, 1o1- 106. 1866. 35. GipELL1, G. Sulla genesi degli apotecii delle Verrucariacex. Nuovo giornale botanico Italiano, 2: 194-206. 1870. 36. HEepiunp, J. T. Kritische Bemerkungen iiber die Flechtengat- tungen Lecanora Ach., Lecidea Ach. und ALicarea Fr. Stockholm. 1892. 37. Hutu, J. M. Ueber Reservestoffbehilter bei Flechten. Bot. Centralblatt, 45: 209-210, 269-270. 18g. 38. Irzicsoun, H. Die Antheridien und Spermatozoén der Flechten. Bot. Zeitung, 8: 393, 913. 1850. / 40. Irzicsoun, H. Wie verhiilt sich Collema zu Nostoc und zu den Nostochineen? Bot. Zeitung, 12: 521-527. 1854. 41. IrzicsoHn, H. Die Gloeocapsen- und Chroococcus-Diamorphose. Bot. Zeitung, 12: 641-651. 1854. 42. Irzicsoun H. Kultur der Glaucogonidien von Pe/tigera canina. Bot. Zeitung, 26: 185-196. 1868. XIV 43. JumELLE, H. L/assimilation chez les lichens. Comptes rendus, 112: 888-893. 1891. ‘ 44. JuMELLE, H. Recherches physiologiques sur les lichens. Rev. gen. Bot. 4: 49-64, 103-121, 159-175, 220-231, 259-272, 305-320. 1892. 45. Kny, L. Ueber die Entwickelung des Thallus von Lichina pyg- maea Ag. und deren Beziehung zu Azvalaria nitida Ag. Soc. Mun. Nov. 21, 1874. 46. Kosert, R. Ueber Giftstoffe der Flechten. Sitzungsberichte der Dorpater Naturforscher-Gesellschaft, 157-166. 1892. (Beihefte Bot. Centralblatt, 1893). 47. KOrBER, G. W. Zur Abwehr der Schwendener-Bornet’schen Flechtentheorie. Breslau. 1574. 48. KrasBe, G. Entwickelungsgeschichte und Morphologie der Poly- morphen Flechtengattung C/adonza. Ein Beitrag zur Kenntniss der As- comyceten. Leipzig. 1891. 49. Kragse, G. Entwickelung, Sprossung und Theilung einiger Flechtenapothecien. Bot. Zeitung, 4o: 65-83, 89-99, 105-116, 221-242. 1882. 50. KREMPELHUBER, A. Rev. J. M. Crombie, ‘*On the Lichen- gonidia Question,” Popular Science Review, July, 1874. Flora, 57: 17-21, 33-45, 49-59-1874. 51. LaGerueim, G. Ueber eine durch die Einwirkung von Pilzhyphen enstandene Varietat von S¢zchococcus bacillaris Nig. Flora, 71: 61-63. 1888. ; 52. Linpau, G. Ueberdie Anlage und Entwickelung einiger Flechten- apothecien. Flora, 71: 451-489. 1888. 53. Linpau, G. Die Beziehung der Flechten zu den Pilzen. Hed- wigia, 34: 195-204. 1895. 54. Linpavu, G. Lichenologische Untersuchungen. Heft I. Ueber Wachsthum und Anheftungsweise der Rindenflechten. Dresden. 1895. 55. Linpsay, W. L. On the spermagones and pycnides of lichens. Proceedings of the Royal Society of Edinburgh, 4: 174-182. March, 1859. 56. Linpsay, W. L. Memoir on the spermagones and pycnides of filamentous, fruticulose and foliaceous lichens. Transactions of the Royal Society of Edinburgh, 22: 101-303. 1859. 57. Linpsay, W. L. On the polymorphism in the fructification of lichens. Quarterly Journal of Microscopical Science, Jan., 1868. 58. Lorsy, J. P. Beitrige zur Biologie der Flechtenflora des Hain- berges bei Gottingen. Inaugural Dissertation. Géttingen. 1890. 59. Lurz, K. G. Ueber die sogenannten Netzbildungen bei Ramadlina reticulata Krplhbr. Ber. deutsch. bot. Ges. 12: 207-214. 1894. XV 60. Maein, A. Organization des lichens. Bull. Soc. Bot. Lyon, 7: 42, 43. 1889. 61. Martretur, U. Un caso di dissociazione naturale nei licheni. Nuovo Giornale Botanico Italiano, 22: 450-451. 18go. 62. Maure, C. Zur Entwickelungsgeschichte von 7yécothectum micro- carpon Arn. Ber. deutsch. bot. Ges. 8: 113-117. 18go. 63. MauLE, C. Ueber die Fruchtanlagen bei Physcta pulverulenta (Schaer.) Nyl. Ber. deutsch. bot. Ges. g: 209-213. 1891. 64. Minxs, A. Das Microgonidium. Ein Beitrag zur Kenntniss des wahren Wesens der Flechten. Basel, Genf, Lyon. 1879. 65. Minxs, A. Beitrige zur Kenntniss des Baues und Lebens der Flechten.—I. Verhandlungen der k. k. zoélogisch-bot. Ges. Wien, 26: 477-600. 1877. 66. Minxs, A. Was ist Myriangium? Eine morphologisch-licheno- graphische Studie. Ber. deutsch bot. Ges. 8: 243-250. 18go. 67. Minxs, A. Beitrage zur Kenntniss des Baues und Lebens der Flechten.—II. Verhandl. der k. k. zodlogisch-bot. Ges. Wien, 42: 377-508. 1892. 68. Motier, A. Ueber die Cultur flechtenbildender Ascomyceten ohne Algen. Inaug. Dissert. Bot. Institutd.k. Akad. Miinster. 1887. 69. Mttier, J. Ein Wort zur Gonidienfrage. Flora, 57: 27-29. 1874. 70. NEuBNER, E. Beitriige zur Kenntniss der Calicieen. Flora, 41: 291-301,-307-317. 1883. 71. NEuBNER, E. Untersuchungen tiber den Thallus und die Frucht- anfange der Calicieen. Ein Beitrag zur Kenntniss der krustig-staubarti- gen Flechten. Wissenschaftlishe Beitrage zu dem IV. Jahresbericht d. k. Gym. zu Plauen, 8: 12. 1893. 72. NyLANnpER, W. De Cephalodiis in Peltidea venosa. Flora, 8: 216. 1866. 73. Oersted, A. S. Spore-planterne. Copenhagen. 1867. 74. Rees. Enstehung der Flechte Collema glaucescens. Monatsber. d. Berliner Akad. 523-533. Oct. 26, 1871. 75. Reinke, J. Abhandlungen tiber Flechten. Jahrb. wiss. Bot. 1894-1896. I. Das Podetium von Cladonia. 26: 495-523. II. Die Stellung der Flechten im Pflanzensystem. 26: 524-542. III. Einige Vorausetzungen einer phylogenetischen Morphologie der Flechten. 28: 19-150. IV. Skizzen zu einer vergleichenden Morphologie des Flechtenthal- lus. 28: 358-486. V. Das Natiirliche Flechtensystem. 2g: 171-236. Xvi 56. Sacus, J. Zur Entwickelungsgeschichte des Col/ema bulbosum Ach. Bot. Zeitung, 13: 1-18. 1855. 77. SCHWENDENER, S. Ueber die Apothecia primitus aperta und de Entwickelungsgeschichte der Apothecien im Allgemeinen. Flora, 21: 321- 332. 1864. 78. ScHWENDENER, S. Ueber den angeblichen Protothallus der Krus- tenflechten. Flora, 26: go1-412. 1866. 79. SCHWENDENER, S. Untersuchungen tiber den Flechtenthallus. Nageli’s Beitrige zur wissenschaftlichen Botanik, 1858, 1863, 1868. So. SCHWENDENER, 8. Ueber die Beziehung zwischen Algen und Flechtengonidien. Bot. Zeitung. 1868. .81. SCHWENDENER, S. Die Algentypen der Flechtengonidien. Basel. 1869. $2. ScuWENDENER, S. Eréterungen zur Gonidien-frage. Flora, 55: 161-166, 177-183, 193-202. 1872. 83. ScHWENDENER, S. Ueber die wahre Natur der Flechten. Ver- handlungen der Schweizerschen naturforsch. Ges. 1887. 84. SPEERSCHNEIDER, J. Zur Anatomie und Entwickelungsgeschichte der Usnea barbata dasypoga Fr. Bot. Zeitung, 12: 193-201, 209-218, 233-243. 1854. 85. SPEERSCHNEIDER, J. .Anatomie der Hagen/a ciliar/s Eschw. Bot. Zeitung, 12: 593-600, 609-616, 625-633. 1854. 86. SPEERSCHNEIDER, J. Zur Anatomie und Entwickelungsgeschichte der Parmelia acetabulum. Bot. Zeitung, 12: 481-495, 497-509. 1854. 88. Sraxs,G. De Korstmossen (Lichenes). Botanisch Jaarboek, 2: 255-304. 1890. 89. StauL, E. 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Note sur lappareil reproducteur dans les Lich- ens et les Champignons. Ann. sc. nat. (III.) 15: 370-350. 1851. 99. Van TiEcHEM, P. Observations 4 propos dune communication de M. Wedell. Bull. Soc. Bot. France, 21: 348-351. 1874. 100. WINTER, G. Untersuchungen der Flechtengattungen Seco/égo, Sarcogyne, Hymenelia und Haetrocymbe. Sitzungsber. d. naturforsch. Ges. zu Leipzig. 1875. tol. WinTER, G. Zur Anatomie einiger Krustenflechten. Flora, 58: 129-139. 1875. 102. Winter, G. Ueber die Gattung Sphacromphale und Verwande. Ein Beitrag zur Anatomie der Krustenflechten. Jahr. wiss. Bot. 10: 245—- 274. 1876. 103. Worontn. Sur les gonidies du Parmelia pulverulenta. Ann. scl. nat. (V.) 16: 317-325. 1872. 104. ZAHLBRUCKNER, A. Die Abhangigkeit der felsenbewohnenden Flechten von ihrer Unterlage. Mittheilungen der Section ftir Naturkunde der Oesterreichischen Touristen Club, II. 18go. 105. ZAHLBRUCKNER, A. Kuntze’s Revisio generum plantarum mit bezug auf einige Flechtengattungen. Hedwigia, 31: 34-38. 1892. -106. Zopr, W. Ueber Pilzfarbstoffe. Bot. Zeitung, 47: 53-61, 69-Sr, 85-92. 1889. 107. ZuKAL, H. Flechtenstudien. Denkschriften der math.- nat. Klasse Kaiserl. Akad. d. Wissenschaften zu Wien, 48: 249-292. 1884. 108. ZuKAL, H. Ueber das Vorkommen von Reservestoffbehaltern bei Kalkpechten. Bot. Zeitung, 44: 701-770. 1886. tog. ZuKAL, H. Halbflechten. Flora, 74: 92-107. 18g1. 110. ZuKAL, H. Morphologische und biologische Untersuchungen iiber die Flechten. Sitzungsberichte der Kaiserlichen Akademie der Wis- senschaften Wien, Math.- Naturwissench. Cl. 104: 1303-1395. 1895. PART I. THE HISTORY, GENERAL MORPITOLOGY AND PHYSIOLOGY OF LICHENS. COAPTER .L THE HISTORY OF LICHENOLOGY. INTRODUCTION. The lichens were more generally neglected by the early botanists than any other group of plants. The causes for this are not far to seek. These plants possess no qualities to make them conspicuous ; they are not, as a rule, striking in color, size or form, nor do they pos- sess very marked useful or harmful properties. Until the advent of scientific botany, herbalists devoted their attention chiefly to the higher plants, which were endowed with real or imaginary medicinal properties, or which served some other use in the household. Later, when lichens began to receive some attention from the lead- ing botanical systematists, they were for a long time subject to great abuse because of careless study. They were taken up asa side study for the information of the few who took a momentary interest in them. Some of the most fantastic and varied vpinions were held with regard to their origin, nature and position in the vegetable king- dom. For these reasons and others, which will become apparent later, it was thought not only interesting but highly important that the student of lichenology should have an insight into the changes which this special science has undergone. It is hoped that the stu- dent may better realize therefrom how much work must yet be accom- plished before our knowledge in regard to these plants can attain any degree of perfection. The historical review here presented is, in the main, a condensed retrospect of Krempelhuber’s Geschichte der Lichenologie. The limitations of the first four periods correspond to those of Krempel- huber; the others are materially changed, and the review has been eS) completed to the beginning of 1897. Other works treating of the history of these plants, notably Lindsay’s British Lichens have also been made use of. Each period is marked by some special evolutionary progress in lichenology. It must not be supposed, however, that these periods are in-reality clearly and distinctly separated. One period gradu- ally merges into the other, which makes the distinction more or less accidental or arbitrary. There are no doubt minds that tower above their contemporaries and whose works are to a certain degree epoch- making; on closer examination it is found, however, that they have built upon the foundation laid by workers that have gone before. Only a few of the more important investigators in lichenology are mentioned. It would be impracticable as well as unnecessary to refer to all the authors who have written on the subject. The publications issued number thousands; to collect and digest these would be the work of many years. The references cited as footnotes are pri- marily of historic interest. The more important references to works having real scientific value are given on pp. xi-xvii. In order to avoid repetition these are referred to by number, where they are mentioned in the historical review, or in the text proper. It is thought most appropriate and convenient to divide the his- tory of lichenology into seven periods, as follows: I. Period: From Theophrastus (371-286 B. C.) to Tourne- fort (1694). II. Period: From Tournefort (1694) to Micheli (1729). III. Period: From Micheli (1729) to Weber (1779). IV. Period: From Weber (1779) to Wallroth and Meyer (1825). V. Period: From Wallroth and Meyer (1825) to Schwen- dener (1868). VI. Period: From Schwendener (1868) to Reinke (1894). VI. Period: Beginning with Reinke (1894). I. PERIOD. From Turopnrastus (371-286 B. C.) ro Tournerort (1694). The earliest references to lichens are all more or less unre- liable. There is little doubt that lichens were known, but they were looked upon as mosses, algae or fungi, and classified with these “i 0 under such comprehensive terms as muscus, bryum, sphagnum. The term lichen (4s¢y7v) was doubtless used to designate various liverworts, especially species of Marchantia. Only after a much later period was this term employed exclusively in application to lichens. Historians are uncertain as to what plant or plants Dios- corides and Plinius intended to designate by the term lichen; it was in all probability a species of Marchantia or other liverwort. The first somewhat authentic references to lichens are to be found in the writings of Theophrastus,’ a pupil and follower of Aristotle. It is generally conceded that this eminent naturalist de- scribed several plants which were doubtless lichens. The very im- perfect descriptions are supposed to refer to Usnea barbata and Po- cella tinctoria. No further record seems to have been made of lichens until the first century of our era when Dioscorides and Plinius again mention the lichens supposed to have been described by Theophrastus. There is little doubt that these authors referred to Focella tinctoria as a ‘* marine fungus growing upon rocks, pos- sessing coloring properties.” Uszea no doubt attracted attention be- cause of its remarkable development. During the dark ages few observations were made on lichens, in fact all scientific progress came to a standstill. Only plants of evident or imaginary medicinal or economic uses were studied. It is remarkable that a period of over seventeen centuries elapsed during which nothing was added to the knowledge of lichens. Ruellius,* Dorstenius* and Gesner,‘ the first commentators on the writings of Theophrastus, Dioscorides and Plinius did little more than to reiterate what had been known of the two lichens above mentioned. We may safely state that up to time of Fuchsius® scarcely anything was known of lichens. There can be little doubt that various lichens came to the notice of botanists and herbalists of the time, but they were not thought of sufficient importance for special study. Then followed a number of botanists who incidentally observed and described a few lichens with which they came in contact during 1A Latin translation by J. Bodaeus. Theophrasti Eresii de Historia Plantarum Libri Decem. 156. Amstelodami. 1644. 2Ruellius, J. De Natura Stirpium Libri III. Paris. 1536. 3Dorstenius. Botanicon continens Herbarum aliorumque Simplicium quorum usus in Medicinis est, etc. Frankfurt. 1540. 4Gesner, K. Historia Plantarum. Basel. 1541. 5Fuchsius, L. De Stirpium Historia Commentarii. Basel. 1549. 4 their collecting trips. We shall mention only a few of these botanists, especially those who were active in the various provinces of Germany and Austria, as well as in other countries of continental Europe. They were Mathiolus,’ Caesalpinus,”? Camerarius,® C. Bauhin,* Clusius® and J. Bauhin.® These and various other authors discovered and de- scribed in all about twenty-eight kinds of lichens: mostly species belonging to the genera Usnea, Stzcta, Cetrarza and Cladonia. The descriptions and attempts at illustration were indeed very defective, so that later authors were often at a loss to know what species was really meant. Up to this epoch lichens had been given no definite position in the vegetable kingdom. They were variously classified with algae, fungi, liverworts and mosses. About this time also we find the first record of observations made on the development and reproduction of Lichens. Porta’ gave some very crude explanations of the origin and growth of Lichens. Malpighi® was the first author to demon- strate the presence of soredia. He also observed that these struc- tures were propagative organs and for that reason considered them as true seeds. One of the most active lichenologists of this period was the Scotch botanist Morison.’ He described fifty-six species in all, of which ten were new; he also gave fairly good illustrations of about twenty-one species. This observer paid little attention, how- ever, to the development of these plants, as is evident from his belief that lichens were excrementitious matter produced by the earth, rocks and trees. This brief retrospect gives some idea of how little was known of lichens at the close of this period. Only such forms as were re- markable for their size, color or use in medicine received any at- tention. The use of focella tinctoria in the processes of dyeing 1Mathiolus, P. A. Commentarii in libros VI Dioscorides de Materia Medica. Venice. 1565 and 1583. *Caesalpinus, A. De Plantis Libri XVI. Florence. 1583. 5Camerarius, J. De Plantis Epitome Utilissima, P. A. Mathioli Senensis. Frank- fort-on-the-Main. 1586. 4Bauhin, C. Phytopinax seu Enumeratio Plantarum Nostro Saeculo Descrip- tarum. Basel. 1596. 5Clusius, C. Historia Plantarum Rariorum cum Appendice et Auctoria et Fig uris 1135. Antwerp. 1601. SBauhin, J. Historia Generalis Plantarum Novae et Absolutae Prodromus. 1619. ‘Porta, J. B. Phytognomonica VIII Libris Contenta. Frankfort. 1591. ®Malpighi, M. Opera Omnia. London. 1686. *Morison, R. Historia Plantarum Universalis Oxoniensis. 1680, 1699, 1715. 5 was doubtless known before the time of Pliny. It is generally sup- posed that the blue and purple of the Old Testament (Ezekiel, XXVII. 7) refers to the dye made from this lichen. It is certain that it had formed for a long period an important article of com- merce. After the fall of the Roman Empire the knowledge of the use of this dye seems to have been lost. In the year 1300, Federigo, a Florentine of German parentage, accidentally rediscovered the meth- od of preparing and using it; he is said to have achieved such suc- cess in his commercial transactions with this substance that in time he became the head of a distinguished family, the Oricellarii, who were later known as Rucellarii and Rucellai. From these names are derived orseille, the name of the coloring substance, and /rocel/a, the genus of lichens from which orseille is prepared. For more than a century Italy supplied the market with orseille derived mainly from lichens collected on the islands of the Mediterranean. After the discovery of the Canary islands in 1402 much of the orseille was derived from those islands, and later from the Cape Verde islands. Later orseille was collected from other islands and coun_ tries. It was also found that other genera besides /tocella furnished excellent dyes; for example, Lecanora, Pertusaria, Umbilicarra. Like other practically inert plants, lichens were supposed to have medicinal properties. Stcta pulmonar7u was strongly recommended in diseases of the lungs. Dorstenius was the first to give a more exact description and illustration of this lichen. He also described the medicinal preparations made therefrom, and their special thera- peutic properties. Because lichens were supposed to have a strong retaining power for various odors and scents they were much used in the preparation of certain perfumes. Some of the fruticose lichens were especially recommended for this purpose. They formed the basis of the renowned Cyprian hair powder (Pulu7s Cyprius), which was supposed to remove dandruff and to promote the growth of hair. Because of the astringent and bitter principles in some species of lichens they were used in tanning and brewing. The beer of a cer- tain Siberian monastery which was noted for its peculiar bitterness owed this to Stcta pulmonaria. Laichens also found a temporary use in the manufacture of paper, pasteboard and parchment. The ‘‘ miraculously”? supplied manna of the Israelites in the wilderness is supposed to have been a species of Lecanora (Lecanora 6 esculenta). This lichen occurs very plentifully in Algeria and Tar- tary, as well as in mountainous districts of other countries. The plant seems to grow and spread rapidly and, being loosely attached, the wind readily carries it down the mountain-sides into the valleys, where the ignorant inhabitants suppose it to have ‘‘rained from heaven.” Travelers in the above countries have reported several noteworthy and extensive ‘¢rains of manna.” The Kirghiz Tar- tars eat this lichen, under the name of ‘‘ earth-bread.” Various other lichens were also used as articles of diet; among them Cetraria Islandica takes perhaps first rank, as it contains a high percentage of lichen-starch (lichenin). However, from the fact that nearly all lichens contain a bitter principle which is very disagree- able to the taste, they were extensively eaten only in arid countries and in times of famine. II. PERIOD. From Tournerort (1694) TO MiIcHELI (1729). As already stated, the lichens were given no definite position in the vegetable kingdom in the previous period. Under the collective name ‘‘muscus” or ‘¢ musco-fungi’’ (Morison), they were variously classed as algae, fungi, liverworts and mosses. The fact which separates this period from the preceding is that lichens were now being looked upon as a distinct class of plants. ‘Tournefort’ was doubtless the first to separate these plants from others and to ar- range them as a distinct class under the comprehensive designation ‘‘lichens.” This in itself was indicative of considerable prog- ress. A group of plants must be given some definite position in the vegetable world before it can receive more careful study. Tourne- fort was one of the few investigators of his time who believed in lay- ing a foundation before beginning to build. He did not concern himself so much with species-making as with a general study of lichens. In all his works he does not describe more than forty-four species and varieties, although fifty-six species and varieties were al- ready known. This noted botanist, who was by no means especially interested in lichens, devoted his limited attentions to them taken collectively, and this led him to arrange them as a separate class. 1Tournefort, J. P. de. Elements de Botanique. Paris. 1694. Institutiones Rei Herbariae. Paris. 1719. 7 His illustrations also lead us to believe that he had more or less cor- rect conceptions of the spores and apothecia. It is much to be re- gretted that Tournefort did not explain his illustrations more fully ; to make matters worse later commentators have variously misinter- preted his explanations. When we consider the imperfection of the magnifying lenses at that time we can not help admiring the excel- lent work done by this French savant. Plukenet' and Petiver? described several new species. They also added some comparatively accurate illustrations. Vaillant® likewise added a number of good illustrations, besides describing several new species. New species were also described by Ray,* Morton’ and others. There were other botanists of various countries who described species of lichens already known and added here and there a few new ones. During this period some seventy new species were de- scribed, which made in all about one hundred and twenty. Nothing was known concerning the physiology of these plants and very little of the minute anatomy. When we consider that the scientific world was already familiar with the names of R. Hook, N. Grew, A. Loewenhoek, J. B. Triumfetti, and with the excellent work done with the simple microscope, we feel convinced that lichens must have been subject to a special neglect, leaving out of consideration the really excellent work of Tournefort. Petiver® is supposed to have given the first description of a lichen from America (St#icta damaecornis). III. PERIOD. From MIcHEL! (1729) TO WEBER (1789). Micheli,’ an Italian botanist, was the first to call attention to the inadequacy of grouping all lichens generically under the designation 1Plukenet, L. Phytographia. London. 1691. Almagestum Botanicum. Lon- don. 1696. Amaltheum Botanicum. London. 1705. 2Petiver, J. Gazophyllaceii Naturae et Artis Decas I.—-X. 1703-1719. Musci Cen- turia X. London. 1695-1703. $Vaillant, S. Botanicon Parisiense. Leide and Amsterdam. 1727. 4Ray, J. Synops. Meth. Stirp. Brit. London. 1690. 1696. 1724. 5Morton, J. Natural History of Northamptonshire. London. 1712. ®Petiver, J. Pterigraphia Americana. London. 1712. ™Micheli, P. A. Nova Plantarum Genera Juxta Tournefortii Methodum Disposita. Florence. 1729. 3 8- Lichen. This generic term became unsatisfactory in proportion as the number of known forms increased. There were, no doubt, botan- ists before Micheli who recognized this defect in lichen classification, but this author was the first to point it out to the botanical world. Micheli went, perhaps, to the opposite extreme and made too many sub- divisions. He divided lichens into thirty-eight orders, basing this division upon the external appearance and consistency of the thallus, the position of the apothecia (receptacula florum), and the soredia (semina). Nineteen of these orders, representing one hundred species, were illustrated. This step in advance was, however, more apparent than real, be- cause of the fact that but little progress had been made in studying the morphology of these plants. It cannot be denied, however, that Micheli made good use of the simple microscope in the study of lichens. The next prominent lichenologist was J. J. Dillen,* who made a considerable change in the system of Micheli. He grouped the lichens with mosses and subdivided them into three classes. These classes were again subdivided into orders, series and divisions, ac- cording to the structure of the thallus, and the structure and position of the apothecia. After Micheli and Dillen other botanists did not hesitate to propose other arrangements, none of which were, perhaps, equal in value to those of the two eminent workers mentioned. These attempts were, however, indirectly productive of good results, because, in order to establish new systems, it was found necessary to make more care- ful observations in regard to the gross, as well as to the minute anat- omy of the thallus and apothecia. Hill,? who classed lichens with mosses, divided all the known species into six genera—Collema, Usnea, Platysma, Cladonia, Pyxidium and Placodium—whose limitations have been retained in part up to modern times. Adanson® classed lichens with fungi and separated them into nine genera. Linné’s‘ system of lichens was in a certain sense retrogressive, since he grouped all these plants under the generic term Lichen (see Tournefort). This group was, 'Dillenius, J. J. Historia Muscorum. London. 1763. * Hill, J. A. History of Plants. London. 1751. 3 Adanson, M. Familles des Plants. Paris. 1763. *Linné, C. Species Plantarum. Holmiae. 1753. “9 however, again subdivided into seven divisions, to which two more were added at a later period. Linné’s system is of special impor- tance, because it shows the first attempt at a natural arrangement. Beginning with Graphis, which he probably supposed to be the lowest form, he gives an ascending series terminating with Usnea, which is certainly a highly developed lichen. Nearly all authors of this period, subsequent to 1753, adopted Linné’s system of classification. The most remarkable characteristic of this period was the re- newed uncertainty as to the position of lichens in the vegetable king- dom. Some authors classed them as fungi, others as algae, again as mosses. This doubt as to their true position continued to agi- tate the minds of botanists, and it has not been definitely removed at the present writing. It would be impossible to review all the works on botany issued during this period which incidentally treat of lichens. As yet no specialists in the study of lichens had arisen; in fact, all the crypto- gams were very much neglected. The study of higher plants of economic and of real or imaginary medicinal value absorbed the at- tention of botanists. The great systematists, in particular, took no interest in the lower forms of plant life. Linné designated lichens as ‘‘rustici pauperrimi,” which may well be rendered ‘* poor trash” of vegetation. In his ‘‘ Species Plantarum” only eighty-six species are mentioned, although 170 were known at the time. Progress in the study of the anatomy and physiology of lichens was especially slow and unsatisfactory although these divisions of botany werealready known. Many botanists seemed possessed with the idea that there must be an analogy between flowering plants and lichens ; hence efforts were made to find the male and female repro- ductive organs, fruit and seed. Wild and fantastic conjectures were made as to what structures in lichens should be compared to special organs in higher plants. Naturally, opinions differed very greatly. Micheli looked upon the soredia as ‘‘ pollen dust,” the apothecia were supposed to be the floral receptacles (receptacula florum), the spores the true ‘‘ flowers.” As already mentioned, this author also explained the asexual propagation of lichens by means of the soredia. Dillen, whose work was likewise of considerable importance, believed that the soredia constituted the pollen. His opinions in regard to the apothecia varied. At one time he supposed them to be the recepta- 10 cles for the seed, again the seed itself, or young plants, or even buds. which served the purpose of reproduction. Gleditsch, Scopoli and Linné believed that the apothecia were the male reproductive organs, while the soredia were the female re- productive organs. Necker’ held the opposite opinion. Haller® ac- cepted the theory of Micheli with regard to the functions of the apothecia and soredia. It scarcely need be stated that these various and varied opinions were based upon purely hypothetical assump- tions and not upon direct observations. In the pages devoted to the previous periods mention has been made of some of the uses to which lichens had been put in medicine and in the arts. In this period further efforts were made to widen their range of supposed usefulness. From the fact that scarcely any- thing was known of their anatomy and chemical composition, it is evident that many erroneous opinions must have been entertained in regard to their usefulness. Mead* recommended Peltigera cantina as a cure forhydrophobia. Dried and finely powdered thalli of P. canina, mixed with finely powdered red pepper, formed the noted ‘‘pulvis antilyssus” (anti-hydrophobia powder) of the London Pharmacopoeia (1721 to 1788). In the history of the Royal Society it is recorded that several mad dogs, belonging to the Duke of York, were saved by this powder. The following is Dr. Mead’s treat- ment in the case of hydrophobia. ‘‘The patient is bled and ordered to take a dose of powder in warm milk for four consecutive mornings; thereafter he must take a cold bath every morning for a month,. and for two weeks subsequently three times a week.” Usnea barbata was a favorite remedy for whooping cough; it was also recommended as an anodyne. (Dioscorides states that it was employed in certain diseases.) From its appearance it was sup- posed to promote the growth of hair. The yellow Xanthoria parietina was recommended in jaundice. The tonic and astringent properties of Cetrarza Islandica were highly lauded by Ebeling.‘ Physicians and apothecaries of Iceland and Denmark recommended it in haemoptysis and phthisis. As an article of diet it had been long in use, not only for man, but also for domestic animals. ‘< Ice- land scurvy ” was said to have been prevented by consuming a suffi- cient quantity of this lichen. 1Necker, N. J. Physiologia Muscorum. Mannheim. 1774. *Haller, A. Historia Stirpium Indigenarum. Helvetiae Bernae. 1768. 3Mead, R. Poisons, 5th ed. 1818. *Ebeling. Du Quassia et Cetraria Islandica. Glasgow. 1749. II IV. PERIOD. From WEBER (1779) TO WALLROTH AND MEYER (1825). In the previous periods lichens were classified mainly according to the differences in the form and structure of the thallus. In this period an attempt was made to classify them according to the ‘* fruit- ing,” that is, according to the form and structure of the apothecia. The first beginnings of this new departure, of course, commenced in the previous period, as we have already noted. Weber,' however, made the first intelligent effort to classify lichens upon this new basis. This author had formerly grouped all lichens in one order under ‘‘Cryptogamia;” he now arranged them under eight genera, Verrucaria, Tubercularia, Sphaerocephalum, Placodium, Lichen, Collema, Cladonia and Usnea ; of these, the first four were based upon the characters of the apothecia alone; the others upon the characters of the thallus, as well as those of the apothecia. The majority of Weber’s contemporaries adopted this new method of classification, with the result that entirely new systems were formed and new genera established. The following were some of the most active systematists: Willdenow,”? who discovered the genus Pe/¢z- gera; Schreber,* who proposed the genera Physcta, Cornicularia, Sticta and Stercocaulon; Humboldt,’ who founded the genus Ofe- grapha. To Persoon’ are credited the genera Calictum, Sphacro- phorus, Baeomyces and Placodium. Although the majority of lichenologists followed in the footsteps of Weber, there were a con- siderable number who could not disengage themselves from the Lin- naean influence. .Of these we will mention only Hagen’ and Joly- clerk.” The Swedish lichenologist Acharius* began his study of lichens tWeber, G. H. Wigger’s Primitiae Florae Holsatiae. Kiel. 1780. Also, Spici- legium Florae Goettingensis. Gothae. 1778. 2Wildenow, C. L. Flora Berolinensis Prodromus. Berolini. 1787. 53Schreber, D. J. C. See Linné’s Genera Plantarum, Sth ed., Vol. I. Frankfort- on-the-Main. 1791. 4Humboldt, A. von. Florae Freibergensis. Berolini. 1793. 5Persoon, C. H. Einige Bemerkungen iiber Flechten. Usteri neue Annalen der Botanik, 1: I-32. 1794. ®Hagen, C.G. Tentamen Historiae Lichenum. Regiomont. 1782. ‘Jolyclerk, N. Cryptogamie complete, ou description des plantes, dont les etami- nes sont peu apparantes. Paris. 1799. 8 Acharius, E. Noy. Act. Reg. Sc. Holmiae, 15: 237-259. 1794. Nov. Act. Reg. Se. Stockholmiae, 16: 1795. ia about 1793, and his great work was issued about seventeen years later (1810). This author divided lichens into three families according to the structure of the thallus: I. Zéchenes crustacet; 11. Lichenes foltace: ; III. Lichenes caulescentes. Each of these families was again divided into several tribes (twenty-eight in all) according to the structure and position of the apothecia. He changed this system very materially at a later period. It would be impossible to mention all lichenologists (including collectors) of greater or less note. However we may state that they made valuable collections at home and abroad and that their main desire was to determine old or new species. Little or nothing was done to ascertain the life-history of any of these interesting plants. Lamarck! described one hundred and fifty-seven species besides a number of doubtful forms. Jolyclerk mentioned and described three hundred and sixty-five species, which was a fairly complete list of all the lichens published at that time. It is, of course, impossible to know whether this was the actual number of species discovered on account of the numerous collections which were not published.' There is also little doubt that many species published were duplicates. The most active collectors were at work in Germany, France, Austria, England and Switzerland. In 1802 it was admitted on good au- thority that in all about five hundred species of lichens were known. In regard to the reproduction of lichens the controversy of the previous period continued; the question was still under discussion as to what lichen structures should be considered as the male and female organs. As in the previous period, these discussions and conclusions were mainly based upon hypothetical assumptions. Hoffmann* agreed with Micheli that the soredia were the true seeds of lichens, but further believed that it was not improbable that the scutellae (apothecia) also contained seed; lichens were thus sup- posed to have a double means of reproduction. The true pollen (fertilizing substance) was supposed to be hidden in the lichen, and that fertilization took place internally during the early development of the plant.* Gartner* perhaps came nearest the truth in regard 1Lamarck,M.de. Encyclopédie Méthodique. Botanique, 3: 470-508. Paris. 1789. ?Hoffmann, G. F. Commentatio de Vario Lichenum usu. Erlangen. 1786. 3 Hoffmann’s general illustrated works on lichens are: 1. Enumeratio Lichenum. Erlangen. 1784. 2. Descriptio et Adumbratio Plantarum. Classes Cryptogamica Linnaei quae Lichenes dicuntur. Leipzig. 1790-1801. ‘Gartner, J. De Fructibus et Seminibus Plantarum. 1788-1805. 13 to the function of the soredia. He believed them to be lateral branches or buds (propagines) and divided them into pulverulent (pulverulentae), filamentous (scobzformes) and leaf-like (dracteo- latae). From this it is evident that his conception of soredia was much more comprehensive than that of the present day, as this au- thor, no doubt, included the so-called isidioid outgrowths as well as the secondary thalloid branches. He stated that the propag7nes took their origin from the surface of the thallus and had the power of de- veloping into new lichens without any preliminary changes. Schreb- er looked upon the soredia as gemmae rather than male reproduc- tive organs, thus agreeing with Gartner within certain limitations. Relhan* and others believed the apothecia were the female sexual organs and the soredia the male sexual organs. One of the most important works of the period was that of Hedwig.* He discovered the spermagonia, and not only gave very good descriptions of these organs, but of the apothecia, the spores and soredia as well. His descriptions were greatly strengthened by good illustrations. His conclusions were essentially as follows: The spermagonia which are the male reproductive organs develop first; subsequently the apothecia and soredia are developed upon them. He believed the apothecia with the spores to be the female reproductive organs, while the soredia constituted the fertilizing elements or the true pollen. As far as his conception of spermagonia and apothecia are concerned, we see that Hedwig anticipated the opinions held by some lichenolo- gists of to-day. His theory with regard to the function of the sore- dia was, however, further from the truth than those of his predeces- sors. We must also mention the rather unique experiments of De Can- dolle? illustrating the method in which lichens were supposed to take up their food-supply. This noted author employed a cochineal solu- tion to observe the manner and rapidity with which various lichens absorbed this substance. As the result, he grouped lichens as to the manner in which he supposed them to absorb their food-supply. 1. Those which take their nourishment through the exterior. 2. Those 1Relhan, R. Flora Cantabrigiensis. Cantabria. 1785. Supplement I. 1786. Supplement II. 1788. 2Hedwig, J. Theoria Generationis et Fructificationis Plantarum Cryptogamarum Linnaei. 1784. 3De Candolle, A. P. Premier essai sur la nutritiondes Lichens. Journal de Physique, de Chimie et d'Histoire naturelle, 47: 107. 1798. 14 which take their nourishment,through a central canal. 3. Those which absorb through the exterior, but which also possess a central canal. As a whole, his explanations are very imperfect, which accounts, perhaps, for the fact that his treatise is at present almost entirely neglected. Georgi’ made some valuable chemical examinations of lichens and demonstrated the presence of oils, resins, gums, alkaline salts, silica, and other substances. Acharius” seems to have been in great doubt as to the origin and structure of lichens. Fora time he even questioned whether they were plants; that they, perhaps, belonged to the polyps. It was this doubt which led him to make more careful investigations concerning these plants. He made an especially careful study of the structure of the apothecia upon which his system? of classification is based. Though this system was doubtless an improvement on previous ones, it was subjected to severe criticism by Weber and other writers- This led Acharius* to improve and enlarge his former work. The illustrations of the structure of the apothecia and thalli are fairly good, but they indicate that he must have used poor microscopes. He gives only a few very crude illustrations of spores. One can readily understand that this system must, of necessity, be very defi- cient because no use was made of the spore-characters. Sprengel® made an attempt to classify lichens according to the structure of the apothecia; it proved to be very unsatisfactory ; it is evident at least, that this author had no definite ideas in regard to the ‘*seed” and ‘* fruit” of these plants. In a later work ® Sprengel adopts the essentials of the system of Acharius and introduces Ger- man diagnoses of species. Of the numerous lichenographers of this period there are ye three who deserve special mention, namely, Fries, Eschweiler and Feé. Fries’ devoted his attention to the purely systematic con- 1Georgi. Chemische Untersuchungen einiger Flechten. Act. Acad. Scien. Petropol. pars. alt. 1779. 2 Acharius, E. Anmarkinger rérande Lafarterne. Kongl. Vet. Acad. Nya Handl. 17: 1796. Prod. Lich. Suec. XVII. 1798. %Acharius, E. Methodus Lichenum. 1803. *Acharius, E. Lichenographia Universalis. Géttingen. 1810. °Sprengel, K. Einleitung in das Studium der cryptogamischen Gewichse. Halle. 1804. English translation. London. 1807. ®Sprengel, K. Anleitung zur Kenntniss der Gewichse. 2d Ed. Halle. 1817. "Fries, E. Conspectus Lichenum. K. Vetensk. Acad. Handl. 323-324. 1821. 15 sideration of lichens, without adding anything important to their morphology. His system of classification is not especially com- mendable, although it was for a time generally accepted. He divided lichens into two great divisions, the Lrchenes gymmnocarpu and Lichenes angiocarpi. The generic distinctions were based upon the form and structure of the apothecia and thallus. Of much greater value are the works of Eschweiler.'. This author, whose early death was a great loss to lichenology as well as to botany in general, made a careful study of the apothecia and spores of lichens. He was the first to call attention to the different forms of spores, al- though his attempts at utilizing these spore-characters in his system of classification met with little success. Feé? in 1824 divided lichens into eighteen orders and sixty-six genera, seventeen of the latter being new. The characters of the thallus were utilized in the determination of the orders. His system was not favorably re- ceived. Fries and Feé will again be mentioned in the following period. In America the work of collecting and naming lichens was also begun with great zeal, although the important work was not done until later periods. Many of the workers of this period devoted themselves to mere catalogueing. Michaux’ published a short list of lichens (mostly new) collected in Carolina and Canada. Miihlen- berg’ published a list of Pennsylvania lichens. Eaton” published a list of North American lichens, likewise Torrey® and Halsey.’ In this period also appeared a number of monographs on lichens. The most noteworthy were those of Acharius who elucidated the genera Arthonia, Thelotrema, Pyrenula, Trypethelium, Calicrum, Glyphis and Chiodecton. Floerke issued monographs on Cladonza and crustaceous lichens. Schaerer wrote a valuable treatise on the Systema Orbis Vegetabilis. Part I. 1825. Lichenographia Europaea reformata. Lund. 1831. 1Eschweiler, Fr. G. Systema Lichenum. Nurenberg. 1824. 2Feé, A. L. A. Essai sur les cryptogames écareés exotiques officinales. Paris T8234: 3Michaux, A. Flora Boreali-Americana. 1803. 4Muhlenberg, H. Catalogue of the Plants of North America. Lancaster, 1813. Second Edition, Philadelphia, 1818. 5Eaton, A. Manual of Botany for North America. Albany. 1818. 6 Torrey, J. A Catalogue of Plants growing spontaneously within 30 miles of New York City. Albany. 1819. 7Halsey, A. Synoptical view of the Lichens growing in the vicinity of the City of New York. Ann. Lyc. Nat. His. N.Y. 1: 3-21. 1824. 16 Gyrophorae of Switzerland. The more important monographs, however, were not issued until the following period. During this period little or no progress was made in the knowl- edge of the anatomy and physiology of lichens. Although the com- pound microscope had been introduced, little use was made of it. This can readily be accounted for by the fact that the first compound microscopes were very imperfect and also because, being an innova- tion, they were regarded with distrust. Eminent opticians of the time boldly declared that the compound microscope could never excel the most perfect simple microscopes. Strange opinions were entertained in regard to the origin of lichens. The belief in spontaneous generation and spontaneous transformation was general. It will be instructive as well as amus- ing to enter more carefully into some of the opinions entertained. Hornschuch! occupied himself with the problems of ‘‘ generation ” and ‘‘ evolution.” His opinions as far as they applied to lichens were as follows: ‘* Algae, lichens and mosses may develop without seed from decomposing water. The decomposition of water induced by warmth and sunlight gives rise to the common ancestral type of the above vegetable forms. This ancestral type is a vegetable infusorium known as Monas lens (green substance of Priestley) which, when acted upon by light and air, undergoes an evolutionary transforma- tion into alga, lichen and moss. Lichens are in reality mosses which have been checked in their evolution and might well be designated vegetable monstrosities. The apothecia (of lichens) are not the fruit, but rather the beginnings of a corolla, analogous to the flower of mosses (Moosréschen). The observations of Micheli in regard to the development of lichens from soredia are to be discredited since the discovery of the spontaneous generation of lichens.” Sprengel? otherwise an accurate observer, believed that Lecrdea immersa and Monilia viridis were evolved from chaotic masses due to the action of some force inherent in nature. The noted algologist Agardh® states that he observed the transformation of /Vostoc muscorum, var. lichen- ordes into Collema limosum. Nees von Esenbeck* was wont to lead ‘Hornschuch, Dr. Einige Beobachtungen iiber das Entstehen der Algen, Flech- ten und Laubmoose. Flora, 2: 140-144. 1819. 2Sprengel, G. Ueber Bau und Natur der Gewidchse. Halle. 1812. ’Agardh, C. A. Dissertatio de Metamorphosi Algarum. Lund. 1820. Flora, 16: 17-41. (Beilage.) 1823. 4Esenbeck, Nees von. Handbuch der Botanik. 1820. 17 his pupils to an old castle in order to demonstrate ad ocu/os how the green substance of Priestley,’ when occurring on rocks, will develop into lichens. These few citations will suffice to show that the science of botany was in its infancy. Better work was being done in the chemical study of lichens. Here the investigations were limited to such lichens as had been found useful in the arts and in medicine. Most of the results ob- tained were published in the various chemical and pharmaceutical journals of the time. Those specially interested will find the refer- ences in various works on lichens. The investigations in regard to the medicinal uses of lichens were not so extensive as in the previous period. During the wars of 1809— 1815 fevers of all sorts were prevalent in military hospitals. Quinine, which was the popular remedy in all cases of fever, became very scarce because of the enormous quantities consumed and because of the commercial blockade of Europe. The Austrian government, therefore, offered a prize of five hundred ducats for the discovery of a cheap available substitute for quinine. Sanders,? who secured this prize in part, proposed Parmelia parretina as a substitute for quinine. It was soon found that the medicinal properties of this lichen were very unsatisfactory and the remedy was abandoned by physicians. V. PERIOD. From WALLROTH AND MEYER (1825) TO SCHWENDENER (1868). This period marks the awakening of scientific lichenology as well as of scientific botany in general. It also marks the discovery of the ‘« gonidia,” which were destined to revolutionize the study and con- ception of lichenology. Likewise the spore-characters were begin- ning to be considered in the various systems of classification. We may well be astounded when we recollect that from Dioscorides to Wallroth, a period of two thousand years or more, the advance made in the exact knowledge of the anatomy of lichens was practically zero. The mere collection and arbitrary arrangement of plants do not give us any insight into their true nature. 1Wiegmann, A. F. Erzeugung mehrerer Gewichse aus der Priestley’schen griinen Materie. Flora, 4: 8-15. 1821. 2Sanders, G. C. H. Die Wandflechte (Parmelia parietina) ein Arzneimittel. Sonderhausen. 1815. 18 The first investigators who entered into a scientific study of lichens were Wallroth’ and Meyer.” It is remarkable that the more important works of these authors should appear in the same year. ‘Their ob- ject was not to collect and classify, but, rather, to study and compare the material already at hand. Of the two investigators it is gener- ally conceded that Wallroth had the clearer insight into the nature of lichens, though in many respects he was not so careful an investigator as Meyer. The student of lichenology will however find, to his sorrow, that Wallroth’s style is very involved. Each sentence contains a long series of parenthetical clauses which makes it very difficult to follow him. His terminology is also new and requires a special study. In spite of all these objectionable features, the work is cer- tainly epoch-making. Wallroth was the first author to give us some knowledge of the vegetative propagative cells (Brutzellen = gonidia). He dwelt at considerable length on the ‘‘metamorphoses” of the thallus as well as on its general morphology. He demonstrated that some lichens were ‘* homoemerous” and some ‘‘ heteromerous” (these two terms are about all that have been retained of Wallroth’s termin- ology). He made a careful study of the soredia and found that they consisted of gonidia enclosed by a delicate network (hyphae), and held the opinion that the gonidia, hence also the soredia, could develop into new plants. Under unfavorable circumstances the gonidium or soredium will not develop into a lichen, but simply form a green coat- ing over the substratum. Though many of the conclusions were er- roneous, it must be borne in mind that this was the first attempt at a scientific study of lichens. It is also much to be regretted that this author did not make use of the compound microscope; in some in- stances there is no evidence that he used even the simple lens. Meyer’s studies were perhaps more comprehensive than those of Wallroth. He entered into a careful consideration of the structure and metamorphosis of the thallus and apothecia, the gonidia and spores, the relation of lichens to the substratum, the growth and nu- trition of lichens, etc. Meyer believed in the spontaneous genera- tion (generatio originarza) of lichens which was stoutly denied by Wallroth. Wallroth believed that the gonidia and spores were the only reproductive organs of lichens. 1Wallroth, F. W. Naturgeschichte der Flechten. Frankfurt-am-Main. I. 1825. II. 1827. *Meyer, G. F. W. Die Entwickelung, Metamorphose und Fortpflanzung der Flechten, etc. Géttingen. 1825. 19 We shall refer briefly to some of the other morphologists of this period. Mohl! made a careful study of the spores of crypto- gams, including those of lichens. Korber* studied the gonidia and in the main verified the conclusions of Wallroth. He also made observations in regard to the reproduction and growth’® of lichens. Korber’s system of lichens‘ has no commendable features, his diagnoses being usually based upon macroscopic examinations. His orders, genera and species correspond to those of Massalongo. One thousand and fifty-one species of lichens are described as oc- curing in Germany and Switzerland. Two hundred and seventy- two species are described as new; from this it may safely be con- cluded that many species are only imaginary. The modern lichen- ologist will find it impossible to recognize many of the species from his descriptions. In passing it may be stated that this criticism will apply to the greater number of systematic works issued during this period as well as in the previous periods. The results of Mas- salongo’s® studies were of considerable importance. This author concluded that the spore-characters, as well as the form and structure of the apothecia and thallus, should be considered in the establish- ment of the genera. It is, however, generally conceded that many of his species and some of his genera were poorly founded. Fries° also recognized the importance of spore-characters in generic dis- tinctions and in addition considered the form of the spermatia and sterigmata of importance in classification. It was, however, left to Stitzenberger (91) to point out the real value and significance of the spore-characters in the classification of lichens. He believed that in general it was necessary to consider the number of septa in the spores as well as their direction. Lichens with spores differing in the number of septa are not to be included in the same genus. He believed that the spores were equal in importance to the flowers and 1Mohl, H. Einige Bemerkungen iiber die Entwickelung und den Bau der Sporen der cryptogamischen Gewiichse. Flora, 16: 32-46, 49-63, 65-73. 1833. 2Ko6rber, G. W. De Gonidiis Lichenum. Berlin. 1839. 3K6rber, G. W. Bemerkungen iiber individuelle Fortpflanzung der Flechten. Flora, 24: 6-14. 17-32. 1841. 4Korber, G. W. Systema Lichenum Germaniae. Breslau. 1855. Parerga Lichenologica. Breslau. 1865. 5 Massalongo, A. Recerche sull’ anatomia dei Licheni crostosi. Verona. 1852. Memoiree Lichenografiche. Verona. 1853. Monografia dei Licheni blasteniospori. Venice. 1853. 6Fries, Th. M. Genera Heterolichenum Europaea recognita. Upsala. 1861. 20 fruit in higher plants; the spermatia were not looked upon as being of any special significance in the classification of lichens. The English lichenologist, Mudd,’ emphasized the importance of the spore-characters and likewise considered the spermagonia as being of only secondary importance. At this time the arrangements proposed by Massalongo and by Korber received general recognition. Now, however, appeared an investigator, an able systematist, who, in a certain sense, revolution- ized the classification of lichens. Nearly all previous lichenologists arranged them beginning with the highest forms and working toward the lowest. Nylander,’ however, had an entirely different conception of how these plants should be arranged. He believed that they presented a double affinity; on the one hand they showed a-close resemblance to fungi, on the other hand to algae. In his system he arranged lichens beginning with those forms most nearly resembling the algae, thence proceeding to the highest forms as Stcta, Parmelia and allied groups. From these highest forms he proceeded to the forms most nearly resembling the fungi. From this it would seem that he had the first somewhat definite conception of the true nature of lichens. The most remarkable thing in his sys- tem is the contempt with which he treated the spore-characters in the limitation of genera and tribes, restricting them to specific distinc- tions. He believed that the form, structure and composition of the thallus, apothecia and spermagonia must form the generic characters. Chemical reactions of the thecium, especially with iodine, were con- sidered of much importance. Nylander also considered the color and structure of the gonidia. He published a list of all the known lichens, which included 1,348 species, 298 of which were described as new.? We have mentioned the leading systematists of the period. We shall now hastily review the works of the leading morphologists of this time. It must not, however, be forgotten that many of the sys- tematists also devoted some attention to the morphology of lichens, but only in so far as it was necessary to enable them to arrange the plants according to some preconceived system. No advanced work was done by them; this was left to the investigators who believed 1Mudd, W. A Manual of British Lichens. Darlington. 1861. 2Nylander, W. Syn. Meth. Lichenum. Paris. 1858. 3Nylander, W. Enumération générale des Lichens avec l’indication sommaire de leur distribution geographique. Cherbourg. 1858. 21 that a thorough study of the life-history, morphology and physiology of plants was necessary before they could be properly classified. Itzigsohn will be the first to receive our attention. His opinions varied in regard to the spermagonia (38). He was inclined to be- lieve that they were parasitic fungi, abnormal spore-organs, apo- thecia or even parasitic lichens. Later (41) he expressed it as his opinion that the spermagonia were the antheridia of lichens analo- gous to those of mosses, and the spermatia, the spermatozoa. Still later (42) he states as the result of the study of Parmelia parietina that the gonidia ‘‘ of lichens which are reproduced from gonidia,” are the female organs and the spermatia the male organs, and that fer- tilization of the gonidia takes place outside of the thallus. Pleuro- coccus, Ulothrix, and other algae were supposed to be unfertilized gonidia enabled to lead an independent existence. Of much more value were the investigations of Tulasne. He gave the first somewhat exact description of the morphology of many lichens (97). Especially valuable are the accompanying illustrations of sections of the thallus, apothecia and spermagonia. This author proposed the term spermagonium for the small structures upon the thallus, and spermatia for the minute rod-like bodies within the sper- magonium. He was also the first to demonstrate that the spermatia are formed on sterigmata, and that they do not have autonomous movement. As to the function of the spermagonia he believed that they were peculiar reproductive organs, physiologically closely re- lated to the apothecia. He was also the first to call attention to the “‘ pycnids” and the ‘‘ stylospores. ” Lindsay likewise did some excellent work in the morphology of lichens. In his prize essay he presents a communication in regard to the morphology of spermagonia and pycnidia. As to their function he is inclined to the belief that they are analogous to male repro- ductive organs. Lindsay has also given us a very interesting and popular history of British lichens.t| This excellent little work con- tains good illustrations showing the morphology of the thallus, apothecia and spermagonia; it gives the history of lichenology, the uses of lichens and diagnoses of the more prominent forms. Schwendener, whom we shall mention more particularly in the next period, now began his interesting studies of lichens (79). He made a careful research on the morphology of the majority of known 1Lindsay, W. L. A popular History of British Lichens. London. 1856. 22 lichens, doubtless the most comprehensive study of the subject ever undertaken up to this time. Especially valuable are his observa- tions in regard to the growth of lichens. His ¢areful study of the anatomy of these plants contributed very valuable aid to the future classification of lichens. It is, however, especially interesting to note that at this time (1858-1863) he was convinced that the gonidia developed from the hyphae, as branches develop from the side of a stem. In this he agreed with Bayrhoffer (5, 5a) and Speerschneider (84). In the next period we shall find that he changed his opinions as far as gonidia were concerned. Not much can be said in favor of the illustrations accompanying Schwendener’s communications. Another important work of the period was that of de Bary.’ In the work cited, this author gave a clear and concise description of the minute structure of lichens. In many respects it resembled the work of Schwendener; in fact, a number of the illustrations were taken from his work. De Bary gave a very comprehensive description of the morphological and anatomical relations of the crustaceous lichens. We cannot enter into a full discussion of de Bary’s work; one opinion expressed by this author should, however, be referred to in particular, since it has bearing upon the conclusions arrived at in the next period. De Bary believed that some of the gelatinous. lichens (/phebe, etc.) were either perfect or mature states of plants whose immature states are recognized as forms of /Vostoc, Chroococ- cus, etc.; or that.these organisms are true algae, attacked by certain ascomycetes, whose hyphae penetrate the algae and form the lichen-thallus. From this we see that De Bary was the first author to hint at the true nature of lichens. He also issued a very valu- able communication in regard to the development of certain lichen- spores (22). Considerable progress was also made in the chemical study of lichens. Various substances peculiar to lichens were discovered, such as cetrarin, variolin, orcin, erythrin, picroerythrin, evernin, physodin, besides various acids, as cetraric acid, evernic acid, and fatty acids. The alkaloids and acids discovered proved so varied and variable that Schunk* came to the conclusion that one ‘De Bary, A. Morphologie und Physiologie der Pilze, Flechten und Myxomyceten. Leipzig. 1866. 2Schunk, E. Einige Bermerkungen iiber die von Stenhouse in der Rocella tinc- toria and Evernia prunastri entdeckten Substanzen. Erdmann’s Journal fiir practische Chemie, 46: 18-30. 1849. 23 and the same lichen would yield different chemical compounds de- pending upon a difference of locality and substratum. French and Scandinavian chemists employed lichens (especially Cladonia rangtferina) in the manufacture of alcohol. These chemical investigations were primarily conducted with a view to improve the dye industry dependent upon the various color- ing substances derived from lichens. France, more than any other country, improved upon the methods of extracting the dye, as well as of applying it. Orseille was especially recommended in dyeing woolen and silken goods. Innumerable methods for extracting the dye as well as for improving its durability were employed. Some of these methods were patented. Lichens also found a wider use as an article of diet. Cetrarza Sslandica, because of its high percentage of lichen-starch (lichenin), was especially recommended as already mentioned. The inhabit- ants of Iceland, Norway and Sweden mixed this lichen with various cereals and mashed potatoes, from which an ‘‘ uncommonly palata- ble and healthful bread was prepared.” Sir John Franklin and his companions made use of this lichen during their Arctic voyages. Its use to prevent the peculiar disease known as ‘Iceland scurvy ” continued. In general, however, it may be stated that lichens were used as an article of diet only in the case of a famine or in those countries where the cereals are not abundant, principally because all lichens contain a bitter principle, which is very disagreeable to the taste and difficult to remove and which has a deleterious effect upon the digestive tract, producing a form of intestinal inflammation. As to the use of lichens in medicine it was found that they were not reliable, and other drugs soon supplanted them. They were, however, recommended as an article of diet for convalescents, espe- cially ‘Iceland moss” (Cefraria Islandica). The peasantry of various countries still believe in the healing properties of various lichens. We have already mentioned Peltzgera cantina. In Sweden Peltigera aphthosa was boiled in milk and given to children afflicted with ‘‘ thrush.” Decoctions of various lichens (especially Parmelias. and Cladontas) were employed in intermittent fevers. The purga- tive properties of most lichens (particularly the Umdbzlicarzas) are well known; various species of Gyrophora and Umobzlicaria were the cause of severe illness among members of the Franklin expedi- tion. 4 24 VI. PERIOD. From ScHuwENnDENER (1868) To REINKE (1894). This is by far the most important period in the entire history of lichenology. It is marked by the recognition of the true nature of lichens and their classification as modified fungi. Since most of the literature of this period is readily accessible I shall not review it at length and shall limit myself to a very brief outline of the work done during this period, mentioning only a few of the leading in- vestigators. The most important work of the period was the discovery of the dual nature of lichens. That is, a lichen consists of a fungal and an algal portion associated in an intimate.organic union. Al- though Schwendener is generally credited with having made known this discovery, it must not be forgotten that the preparatory work was done in the preceding period; also that Schwendener did not at first believe in the dual nature of lichens. Not until the year 1868 (79) did he express the opinion that the gonidia of various lichens corresponded to certain low forms of algae. His conclu- sions of that time may be summarized as follows: 1. There is no direct proof of any genetic relation between the gonidia and the hyphal elements. 2. The cell-walls of the gonidia have a different chemical be- havior from the membranes of the hyphae; the former react similarly to those of algae, the latter similarly to those of fungi. 3. As to structure and development the various forms of gonidia- correspond to different forms of algae. The resemblance is so close that in many cases a given isolated gonidium cannot be distinguished from the corresponding alga. The algal types are as follows: (a) The majority of heteromerous lichens (Usxea, Bryopogon, Evernia, Physica, Anaptychia, Imbricaria, Parmelia, etc.), con- tain species of the algal genus Cysfococcus Naeg. (C. humicola and related forms). (b) Some other heteromerous lichens contain species of Pleuro- coccus Menegh. (/. vulgaris and related forms). (c) In Rocella we find the algal genus Axococcus Naeg. (d) Omphalaria and other lichens with blue-green gonidia con- tain various representatives of the Chroococcaceae as Gloeocapsa, Chroococcus, and perhaps other related forms. 25 (e) The Collemaceae are associated with /Vostoc. (f) Aphebe and related genera with Stigonema. (Ephebella flegetschweilert with Scytonema. ) (g) Hormogonium and Cystocoleus are associated with an alga belonging to the Confervaceae. (h) Graphis, Opegrapha and related forms are associated with Chroolepus. 4. The development of the spore never proceeds further than the protothalloid stage, perhaps because of the absence of the requisite algae. 5. There is a great similarity between the lichens and the pyreno- mycetous fungi. Schwendener issued a communication on the algal types of lichens in the following year (81). It is accompanied by colored plates illustrating most of the lichen-algae. Famintzin and Baranetzky (23, 24) demonstrated experimentally that the gonidia of heteromerous lichens, such as Physcra, Evernia, Cladunia and Peltigera, as well as some of the gelatinous lichens, as Col/ema, are capable of devel- oping apart from the thallus, even producing zoospores like the uni- cellular algae. In spite of this fact these investigators concluded that the gonidia were not algae, and further expressed the opinion that perhaps many of the unicellular algae were simply free lichen- gonidia. Woronin (103) demonstrated that the gonidia of Parmelia pul- verulenta never produce hyphal filaments, but always develop into new gonidia; or, what is the same thing, the free gonidium which is neither more nor less than a species of Cyst¢ococcus develops into new colonies of algae. He thus opposes the view held by Baranetzky and Famintzin and favors the theory of Schwendener. Rees (74) demonstrated that the hyphae developed from the spores of CoMema glaucescens will not mature unless associated with WVostoc lichenordes ; in the absence of such an association the young hyphae soon perish. A few years later Bornet (15, 16) isolated and determined specifically the algae which enter into the composition of a large number of lichens. He also described the method by which the hyphae envelop the algae, as well as the mutual benefit derived from the intimate asso- ciation of algae and fungi. Similar observations were made by ‘Treub (94). These and other experiments demonstrated beyond a doubt the 26 dual nature of lichens. They also demonstrated that this association was not like that of ordinary parasitism, but rather formed a union for mutual benefit, thus enabling these plants to exist where neither of the camponents could exist alone. This association was known as consortism (Reinke), or symbiosis (de Bary). There were also a large number of investigators engaged in the study of the morphology as well as the physiology of particular groups. of lichens as wellas of lichens in general. We will mention afew of these. Stahl (89, 90) made a special study of the spermagonia. His ' conclusions were that in Co//ema the spermatia are the male reproduc- tive organs. Thefemale reproductive organ known as the carpogone after being fertilized by the spermatia develops into the apothecium. It is interesting to note that this form of sexual reproduction was ob- served only in Col/lema. Recently Sturgis has apparently verified Stahl’s results (93). Further investigations are necessary to estab- lish Stahl’s theory. A number of investigators have demonstrated that the spermatia will develop a hyphal network, even developing new spermagonia. This would seem to prove that spermatia are true spores instead of sexual organs. The most important work in re- gard to the physiology of lichens was done by Jumelle (44). This. author gave us the first reliable results of observations made on the exchanges of gases in fruticose and foliose as well as in crustaceous. lichens. He found that the exchange of O for CO, is independent of the substratum and dependent upon sunlight and moisture, and also- that this gaseous exchange varies greatly in different lichens. An excess of moisture reduces carbon-assimilation. Respiration in some lichens still goes on at very low temperatures, — 10° to — 40° C. Lichens can also resist much higher temperatures than phanerogams. For instance, respiration was still active when the lichen was exposed. for one day to a temperature of 45° C., three hours at 50° C. and. one-half hour at 60° C. Among the systematists we will mention Tuckerman,! who con-: sidered Kérber’s system the most useful and adopted it in his classifica- tion of the North American lichens; his diagnoses are carefully given, accompanied by spore-measurements. With Nylander he considered the spermagonia of great importance in classification.