PROCEEDINGS 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY 



HELD AT PHILADELPHIA 

 FOR PROMOTING USEFUL KNOWLEDGE 



Vol. XLVII Sept. -Dec, 1908. No. 190. 



HEREDITY, VARIATION AND EVOLUTION IN 

 PROTOZOA. II. 



Heredity and Variation of Size and Form in Paramecium, 



WITH Studies of Growth, Environmental Action 



AND Selection.^ 



By H. S. JENNINGS. 



(Read April 24, 1908.) 



TABLE OF CONTENTS. 

 (See pages 544-546.) 



I. INTRODUCTORY. 



The first of this series of studies- gave a general introduction to 

 the investigations, and dealt with the fate of new or acquired char- 

 acters in protozoa, showing that these are as a rule not inherited and 

 that there is no difference in principle on this point between protozoa 

 and metazoa. The present paper takes up heredity and variation in 

 size and form in Paramecium. 



Our present questions are then mainly as follows : In what respects 

 do the individuals of Paramecium resemble each other? In what 



^ From the Laboratory of Experimental Zoology, Johns Hopkins Uni- 

 versity, Baltimore, Md. 



'Journal of Experimental Zoology, Vol. 5, 1908, pp. 577-632. 



PROC. AMER. PHIL. SOC. XLVII. 190 Z, PRINTED J.A.NU.\RY 8, I909. 



