VITALITY 



245 



(p. 218). In the other case the sixteen macronuclei would all fuse 

 to form one single macronucleus which would divide and form two 

 groups of eight each (Fig. 129). In the latter case there was not 



Fig. 127. — Uroleptus mobilis; origin of double individual. Above, two conju- 

 gating cells; below, the double individual which was formed by the fusion of two such 

 conjugating individuals. (Original.) 



only a definite adaptation to the new conditions but a further 

 advance toward a composite animal of a new type and with a novel 

 organization. The synchronous activities indicate that common 



