16 



LIFE, IN IT3 LOWER FORMS. 



fine granules, some larger globules, probably of oil (fat), a 

 contractile sac anteriorly, and an elliptic discoid granular 

 nucleus, often accompanied by another smaller, finely 

 granular, discoid globule, well defined. 



" The larger nucleus is the one destined to undergo the 

 first change ; this it does by the development of fine cilia 

 around its periphery, which actively vibrate, and so cause 

 its rotation. Whilst this goes on, it increases in size, ad- 

 vances towards the anterior of the Acineta, which takes on 

 active contractions, and thereby ultimately ruptures its 

 integument, allowing the embyro (ciliated nucleus) to 

 escape. On its emergence, the embyro swims away rapidly 

 by means of its cilia ; 'what further changes it undergoes 

 are yet to be discovered. 



" However, the part the Acineta body has to perform is 

 not completed by the production of the one embryo ; but 

 the saine process has to be repeated again and again, until 

 its formative granular mass is used up, when the Acineta 

 becomes a contracted, shrivelled, empty sac, seated upon 

 the persistent stalk. 



" After an emission of an embryo, the Acineta body 

 contracts strongly ; some of its diverging fibres shorten, 

 whilst others are entirely withdrawn. This contracted 

 condition, after lasting for a time, relaxes; the Acineta 

 resumes its usual movements ; the fibres spread out 

 anew, moving about as usual in various directions j and 

 it finally regains its original characters, save that it is 

 smaller, and, instead of a smooth, even surface, it has its 

 tunic thrown into folds or undulations. The spot from 

 whence the embyro escaped soon becomes imperceptible.'"' 



* Condensed from Stein, in Pritcbaid's Hist, of In/us. Animate., p. 537. 

 " (Ed. 1852.) 



