434 



JENNINGS— HEREDITY IN PROTOZOA. 



[April 24, 



relative sizes, are given in Fig. 4. These may be compared with the 

 adults of this race, a to c, Fig. i. 



Fig. 4. Young Paramecia, descendants of D (caitdatuin form), from 

 immediately after separation to the age of 19 minutes, a has just separated; 

 b, c and d are two to three minutes old ; i and ; are 19 minutes old ; the 

 others are intermediate. These should be compared with the adults a to c 

 of Fig. I (page 403), which are drawn to the same scale. All X 235. 



(e) Age 18 to 28 Minutes (Tables XXXIII. and XXXIV.).— 

 The first lot of this age (row 8, Table X.) contained 49 specimens 

 (Table XXXIII.) and came on the same day from the same lot as 

 the first lot of 24 of the preceding stage, so that the two are strictly 

 comparable. The mean length has increased in the period of about 

 thirteen minutes by nearly 16 microns, while the mean breadth has 

 decreased 7 to 8 microns. The ratio of breadth to length has decreased 

 almiOst 10 per cent. The correlation between length and breadth is 

 in the present lot positive though small (.1937)- If we should throw 

 together the two lots (rows 7 and 8, Table X.), the correlation 

 would, of course, be decidedly negative. 



A second lot of 57 specimens aged 18 to 28 minutes was taken 

 from the same culture about two weeks later. If we throw the two 



