186 



THEORY OF EVOLUTION 



tween parent and offspring. If this is correct, 

 and if in the protozoa the chromatin has the 

 same influence tliat it seems to have in higher 

 animals, the mode of reproduction in Difflugia 

 wonkl be expected to give httle more than ran- 

 dom samphng of the gei'm j^lasm. 



Jennings was able by means of selection to 

 get from tlie descendants of one original indi- 



FiG. 93. Races of Difflugia. (After Leidy.) 



vidual a number of diff'erent types that them- 

 selves Iwed true, except in so far as selection 

 could affect another change in them. In this 

 connection it is interesting to note that Leidj^ 



