72 INFUSOEIA. 



ther, their months being closely applied to one 

 another, and in this condition they move rapidly 

 through the water wherein they are confined. 

 Next, the nucleolus of each undergoes a consider- 

 able increase in size, and assumes the form of an 

 ovate capsule striated on its surface. It then 

 divides into two or four parts which increase inde- 

 pendently of one another, and form a number of 

 secondary capsules. Meanwhile the nucleus also 

 enlarges, becoming at the same time rounder, 

 wider, and softer in consistence; a number of 

 transjDarent spherical bodies are formed in its inte- 

 rior, within each of which an obscure central point 

 may be observed. Sometimes the nucleus breaks 

 up into fragments, previous to the formation of the 

 spherical bodies. After a certain period has been 

 permitted to elapse, a transfer is effected by the 

 two conjoined Paramecia of one or more of their 

 secondary capsules, which pass through the closely 

 appressed mouths from the body of one into that 

 of the other. But this does not hinder the further 

 increase of the capsules in size, which still con- 

 tinues after their transference has taken place, one 

 only arriving at maturity at the same time. Five 

 or six days after copulation minute rounded germs 

 make their appearance; these for a time remain 

 attached to the body of the parent animal by 

 means of the suckers "with which they are pro- 

 vided. At length they detach themselves, lose 

 their suckers, acquire a mouth in their stead, and, 

 becoming fm'nished with vibratile cilia, take on 

 the aspect of adult Parmnecia. 



Such are the facts as stated by M. Balbiani. 

 He explains them by regarding the nucleus as an 

 ovar^', its contents as ovules, and each of the 



