418 THE BEGINNINGS OF LIFE. 



the green vesicles containing eight corpuscles ranged 

 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 Euglense (see 

 Fig. 85,7.) 



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 

 Vaucheria. They enlarge and become of a pale green 

 colour, and whilst this colouring matter limits itself 

 to a surface layer, a few colourless granules appear in 

 the central portion of the vesicles (Fig. 82, 3 '.) 

 These vesicles gradually elongate so as to form rudi- 

 mentary filaments, which after a time give off lateral 

 buds and develop dissepiments at intervals 1 . At other 

 times, various kinds of Desmids originate most plen- 

 tifully from Algx 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 



1 Dr. Gros has evidently watched the same mode of transformation in 

 vesicles .derived from Euglense. Speaking of these, he says : ' On peut 

 ajouter encore que ces parcelles v^siculaires continuent a s'organiser 

 pour devenir des Closteriens aigues.' (Loc. cit., p. 302.) 



