KNOWLEDGE OF CRYPTOGAMOUS PLANTS. 259 



publication of a work on all the mosses, for we may well cxi)ect some- 

 tliiug excellent from liim. The next author of importance is C. JMiiller, 

 who published a synopsis of all known mosses, in two volumes. lie de- 

 serves our thorough ai)preciation for his diligence in collecting the ex- 

 isting material. His views on system, however, are less happy. Led 

 by the consideration of certain characteristics, he often classiiies very 

 different species together, and separates those closely related. Among 

 other writings on exotic mosses, we must mentioned ])ozy and ]\[olken- 

 boer's " Musciinediii Arcliipdagi IndiclJ^ and their " BryoJogiaJaranica,"^ 

 which was continued after their death by Van der Bosch, and Van der 

 Sande Lacosta. They follow the same plan as the " Brijologla Enyopca^'^ 

 and are, therefore, of great value. The works of Sullivant, on the moss 

 flora of North America, and those of Wilson, Mitten, and Hampe, are 

 also of considerable importance. 



In the last class, thatof the ferns, a series of tliemost important discov- 

 eries was inaugurated by Nilgeli. He observed that the antheridia. or 

 male organs of fructitication, were developed upon the prothallium, 

 which originates directly from the germinating spore. Count Lesczyc 

 Snininski followed np his discovery by proving that the prothallium 

 contained also the archegonia or female organs. Through these two 

 brilliant discoveries new prospects were opened for the morphology of 

 ferns. We recognized that in this whole class of plans fructitication was 

 effected on the small prothallium, and that the foliage, which we ha<l been 

 accustomed to take for the whole plant, was developed only when fructifica- 

 tion had taken place. Schacht, Mettenius, and especially llol'meister, 

 deserve great credit for following- up these discoveries. The brilliant re- 

 searches of the latter author in particular, have made known to us the 

 exact process of fecundation, and we now understand that the so-called 

 large and small spores of the selaginella and water-fern are nothing- 

 more than the female and male organs of these plants. Ilofmeister has 

 furthermore ascertained with unexampled acuteness the laws according" 

 to which the leafy plant is developed from the impregnated germ- vesicle 

 of the archegonium, and also how the stem grows, and how the fans are 

 formed. Although Ilofmeister came to the erroneous conclusion that the 

 latter were not true leaves, but peculiarly transforn^.ed branches, the value 

 of the grand discoveries of this most original ami thorough of all orgauo- 

 graphists of the acirogens renmins unimpaired. Hugo von Mold has 

 drawn a masterly picture of tlu' structure of the stem of tree-ferns, in 

 his classical desertation, which has since been developed more in detail, 

 partly by himself and partly by otlier authors. The most thorough in- 

 vestigation of the development of the iudusiuni and sporangium are due 

 to iSchacht. 



Besides the older works of Kaulfuss and Kunze on the classifiea- 

 tiou of ferns, we must mention especially the numerous pteridograpliic 

 works of Hooker, which have considerably adxanced our knowledge of 

 the subject by their excellent illustrytions. The works of K. 1>. Bresl 



