41 8 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 (sse 



Fig- 85, I) 



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, w, w'.) 

 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 Algae and Characeae 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 transformation in 

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

 aj outer encore que ces parcelles vesiculaires continuent a s'organiser 

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



