Heredity in Protozoa 



6ii 



ness, and the projecting angle became more marked (Fig. 14, ^'). 

 On the third day it divided; the posterior product was normal in 

 shape, though smaller than usual, while the anterior product 

 was extremely irregular, having the form shown in Fig. 14, ^. 



In the next twenty-four hours this irregular structure underwent 

 a partial division, increasing its size and irregularity of form (Fig. 

 14, ^). The structure thus produced was double, since it had two 

 mouths (m), both of which took food; and there were two independ- 

 ent protoplasmic circuits for the digestion of food. 



During the next twenty-four hours this structure divided into 

 two very unequal parts. One product was a short, somewhat 



Fig. 13 History of a race derived from an individual with a crooked posterior tip. The irregularity 

 had nearly disappeared in the second generation; in the third (not shown) it was quite gone. 



irregular individual. The larger product was still very irregular; 

 it represents three united individuals (Fig. 14, ^). 



The smaller product divided again, producing progeny that were 

 normal in form, though small in size. 



The larger product, composed of three incompletely separated 

 individuals, did not divide again; after two days it disintegrated. 



3 The individual aq represents mainly the third category, in 

 which the irregularity of form is increased in reproduction, till 

 death occurs. This specimen was curved as shown in Fig. 15, a. 

 At its first division the products did not completely separate, but 

 formed the structure shown in Fig. 15, b. At the next division 

 the right half divided in such a way as to produce one nearly nor- 



