6io 



H. S. 'Jennings 



ness of the parent (Fig. 4, ^) caused a spine to appear on one of the 

 progeny; this persisted on a single member of each generation, as 

 long as it was followed (22 generations). The other progeny were 

 normal. 



2 The individual al was bent a little in front of the middle so as 

 to form nearly a right angle (Fig. 12, ^). At the first division 

 the posterior product was of the normal form, while the anterior 

 product was somewhat irregular (Fig. 12, ^) but less so than the 

 parent. When this divided, the two individuals resulting were 

 both of the normal form. Regulation occurs during the process 

 of fission. 



Fig. 12 History of a race derived from a crooked specimen. The crookedness had disappeared in 

 the third generation. 



The individual ab had the posterior end crooked (Fig. 13). 

 When this animal was placed in the culture fluid, it became 

 plumper, and the abnormality of form was less marked (^'). 

 When it divided the anterior product was of the normal form, 

 while the posterior product had the posterior point slightly dis- 

 placed toward the aboral side, but was otherwise normal (Fig. 13,^). 

 When it again divided, its progeny were both normal in form. 



The case of aj belongs partly in the second category, partly in 

 the third. The body of the parent aj was small and irregular, 

 with a broad anterior end, which bore on one angle a projecting 

 point (Fig. 14, 1). 



When this was placed in the culture fluid it did not divide for 

 three days. The body increased in size and especially in thick- 



