200 FLORENCE A. WAITERS. 



jugants only 7 pairs show a greater variation than 3.5 mm. This 

 indicates a very definite correlation of size between the two 

 members of the conjugating pairs. 



The same conditions which Pearl ('07) and Jennings ('n) 

 found to exist in Paramcecium, then, have been shown to exist 

 in the case of Blepharisma undulans, i. e., (i) the mean length 

 of the conjugants is less than that of the non-conjugants, (2) 

 the variation of the conjugants is less than that of the non-con- 

 jugants, and (3) there is a definite positive correlation in size 

 between the members of the conjugating pairs, the larger uniting 

 with the larger individuals and the smaller with the smaller. 



REFERENCES. 

 Pearl, R. 



'07 A Biometrical Study of Conjugation in Paramcecium. Biometrika, Vol. 

 V., pp. 213-297. 



Jennings, H. S. 



'n Assertive Mating, Variability and Inheritance of Size in the Conjugation 

 of Paramxcium. Jour. Exp. Zool., Vol. II., No. i, July, 1911. 



