ii6 The Third and Fourth Generation 



already mentioned even more than the offspring 

 of alcoholized parents. In other words, the 

 grandchildren suffered more than the children 

 from the debauches of their ancestors. The 

 only conclusion that we care to draw at present 

 is that germ cells evidently may be directly 

 affected by factors in the environment. 



Experiments on other animals made in the 

 same way as Stockard's experiments indicate 

 that the results achieved by Stockard do not 

 necessarily obtain in all their details. White 

 rats were tested as foUows to determine the 

 rate at which they learned. They were first 

 accustomed to feed at one corner of their cage. 

 Then partitions were set in so that the food 

 was out of sight at the end of a maze of pas- 

 sages. Each rat was tested separately and at 

 first wandered about in a tortuous course in its 

 attempt to find the customary food. In the 

 course of repeated trials day after day it learned 

 to omit some of the unnecessary windings and 

 finally went directly to the food. The length 

 of time it took a rat to learn its way unerringly 

 along the passages to the food was an index of 



