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 

 Paramectum colpoda in Pritchard's c Infusoria/ namely, 

 c 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 



1 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 Penicillium filaments (into conidia), and of encysted 

 Euglena, have several times been seen under similar circumstances. 



