^ 



rn^ 



418 



THE BEGINNINGS OF LIFE. 



the green vesicles containing eight corpuscles rano-ed 

 themselves in one plane and in close apposition, so as 

 to constitute what appeared to be an embryo Micra- 

 sterias. In this, as in other respects, the transforma- 

 tions of these vesicles were similar to those which have 

 been observed to take place 



amongst Euglen^ (see 



to a surface layer^ a few colourless granules appear in 

 the * central portion of the vesicles (Fig, %i^ n^ n.) 

 These vesicles gradually elongate so as to form rudi- 

 mentary filaments, which after a time give off lateral 

 buds and develop dissepiments at intervals ^. At other 

 times, various kinds of Desmids originate most plen- 

 tifully from Algse and Characese by a different process. 

 A minute tubular bud appears at some portion of the 

 surface of the filament, which as it enlarges acquires 

 green contents. It rapidly grows into some kind of 

 filamentous Desmid — some of the specimens being 

 very narrow and others broad, and of a very bright 



^ Dr. Gros has evidently watched the same mode of transfoimation in 

 .vesicles derived from Euglen^. Speaking of these, he says : — ' On peut 

 ajouter encore que ces parcelles vesiculaires continuent a s*organiser 

 pour devenir des Closteriens aigues/ (Log. cit., p. 302.) 



i^^^^^ .Q^C^ 



^ ana of b^- 



Fig- 85, /•) 



Individual chlorophyll vesicles of Vaucheria and Ni- 

 tella may also gradually metamorphose themselves into 

 Desmids. I have seen this change take place with the 

 greatest distinctness in some of the corpuscles of the 



r 



Vaucheria, They enlarge and become of a pale green 



colour^ and whilst this colouring matter limits itself j pr to grow from 



(eiitre 



an aggreg^ 



each of which 

 aosforming use 



tr 



(o'wliich they are 

 ine tubular pe 

 n[\)^ to whi 



Cest une cho; 



e 



k obse 



rvatcurs q 



tos le tube d 



( 



Navicules. 



3 



Alth 



Wain 



kind, ii 



in I 



sp^'cimen' 

 ^"ich but • 



'''^^ nor De, 



h 



¥Xi 



ofth 



: possii 



