204 Morphology and Systematic Botany under [BOOKI. 



1850 ; what was certainly known about them only showed how 

 uncertain the rest was ; the Algae, Fungi, and Lichens pre- 

 sented a chaotic mass of .obscure forms in contrast with the 

 well-ordered knowledge of the Muscineae and Vascular plants. 

 In the Mosses and Ferns the series of developments within the 

 limits of the species was so set forth in its several stages, that 

 all the important points in the advancing growth were clearly 

 ascertained, while the alternation of generations at once sharply 

 distinguished and connected together the chief sections in the 

 development ; on the other hand the development of the Algae 

 and Fungi seemed to break up into a disorderly and motley 

 throng of forms that appeared and disappeared, and it seemed 

 scarcely possible to discover their regular genetic connection. 

 Here the important point was to determine which of the known 

 forms belonged to one and the same cycle of development, for 

 these plants go back at the most various stages of development 

 to the segregation of single cells, which are the beginning of a 

 new development either repeating or carrying on the old one. 

 The beginnings of the most different species of Algae lay mixed 

 up together in the same drop of water, those of quite different 

 Fungi grew together and even upon one another on the same 

 substratum ; in the Lichens, Fungus and Alga were united 

 together. Such was the case with the small and microscopic 

 species; the large Seaweeds, the Mushrooms, and the large 

 Lichens were easier to distinguish specifically, but less if 

 possible was known of their development than of that of the 

 microscopic Thallophytes. 



Nevertheless the knowledge of individual forms in these 

 organisms had been considerably extended before 1850. 

 Collectors and amateurs, intent only on determining what is 

 immediately presented to the eye and making little enquiry 

 into origin and affinities, were indefatigable in adding to their 

 collections, and made catalogues and proposed various systems 

 founded on external marks taken at pleasure. The names of 

 species were counted by thousands, their characters filled thick 



