KNOWLEDGE OF CRYPTOGAMOUS PLx\XTS. 2,) t 



t'nug'i. vSiiice tlie publication of liis ^ysiema Dnjcologicum, about forty 

 years ago, no work bas appeared which inchicles all orders, geuera, and 

 species of this class. Indeed, the works of Fries are so excellent that 

 they may be held up as models to all botanical authors. The writer, who 

 passed a third of his unusually long life in the woods, where he studiiMl 

 fungi, acquired a wider experience than any other. He has grouped the 

 geuera naturally, and described the species with true Linnean precision. 

 His work is, therefore, the basis of all mycological studies. The other 

 authors contented themselves either with writing local iloras or study- 

 ing single orders for the purpose of furnishing materials for a future 

 Si/sfema mycologlmnn. Many excellent works of this kind have been pro- 

 duced, especially those of Leveille, Bonorden, Fresenius, De Barry, aud 

 the thorough treatises on exotic forms by Montaigne and Berkeky. 



In the class of the mosses, the morphological studies of many thor- 

 ough scholars have progressed so iar that these plants are now among 

 the most perfectly known. Mirbel has furnished interesting data on 

 the structure of the leaves aud the development of the sporangia of the 

 Marchant'ia poJymor})lia. The works of Bischoffon liverworts, although 

 treating chiefly of classilication, i^resent a great many new^ observations 

 on the structure and development of the fruit. The excellent natural 

 history of liverworts by IS'ees von Esenbeck,to which I will revert again, 

 lurnishes many important contributions to orgauography. A celebrated 

 essay of Hugo von Mold on the spores of acrogeus proves that four 

 spores are formed in every cell, analogous to the formation of pollen- 

 cells. Gottschee, finally, has published very thorough essays on the 

 structure aud development of single groups of liverworts. All these 

 writings are left in the shade, however, as far as the organography of 

 ferns and mosses is concerned, by those of IJofmeister, the most prom- 

 inent investigator of the subject. This excellent scholar has set him- 

 self the task of pursuing the development of the acrogeus down to the 

 simple cell, and he has succeeded in many cases. Through him we know 

 how the germ of mosses is formed and grows, how the stem is devel- 

 oped, and how the leaves appear and form. We not only understand 

 the structure of the antheridia perfectly, aud know how the seed fila- 

 ments are formed, but we have also gained an insight into the structure 

 of the archegouia. We are able to follow exactly the process of fructi- 

 fication, and see how the complicated moss-fruit is developed after fruc- 

 tifieation by the archegonium, from the riccia, the most simple type, up 

 to the most highly-developed forms, according to one fundamental idea, 

 llofmeister has illustrated all these discoveries with excellent drawings, 

 so that tlie study of his masterpiece, "Comparative investigations iu 

 the development of the higher cryptogams," is one of the most grate- 

 ful tasks, although it is a very laborious one, on account of the peculiar 

 manner in which it is written. 



Hofmeister's work is also the most important source for the morpho- 

 logical study of foliaceous mosses. ^JSTageli has determined the laws of 

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