250 THE BEGINNINGS OF LIFE. 



resulted from the fission of some smaller portion of 

 the embryo mass. Sometimes it was the largest em- 

 bryos which were observed to undergo this process 

 of fission, though it was by no means confined to 

 them ^ 



On emerging from the cyst all the embryos, although 

 differing somewhat in size^ were of the same shape. 

 This closely corresponded with the description given of 

 Paramecium colpoda in Pritchard's "^Infusoria/ namely, 

 ^ Obovate, slightly compressed ; ends obtuse, the ante- 

 rior attenuated and slightly bent like a hook.' Cilia 

 existed over the whole body, though they were largest 

 and most numerous about the anterior extremity. No 

 trace of an actual buccal cleft could be detected^ and 

 (except in the posterior portion of the body, where a 

 large and very persistent vacuole was situated) the 

 organism was everywhere densely packed with the 

 large, homogeneous, biscuit-shaped particles. For many 

 days these most active Infusoria seemed to undergo 

 little change, though afterwards the number of the con- 

 tained particles gradually began to diminish, whilst the 

 body became more and more regularly ovoid, and a 

 faint appearance of longitudinal striation manifested 

 itself — more especially over its anterior half. At the 



^ Partial desiccation has a strong tendency to induce such fission, as I 

 found by the frequency with which it occurred when the water had in 

 great part evaporated from specimens placed in a developmental cham- 

 ber. Fission of Penicilliiim filaments (into conidia), and of encysted 

 EuglencE, have several times been seen under similar circumstances- 



