358 HEREDITY AND ENVIRONMENT 



it does not change the hereditary constitution. 

 Woltereck found that in Daphnia there is an 

 after effect of cold lasting for one or two gen- 

 erations, and this he calls "induction" when the 

 effect lasts for one generation, or "preinduc- 

 tion" when it lasts for two or three genera- 

 tions. Whitney found that rotifers poisoned 

 with alcohol were weaker in resistance to cop- 

 per salts and were less fertile than others, and 

 when brought back to normal conditions the 

 first generation was weak but the second was 

 normal. On the other hand Stockard finds that 

 the injurious effects of alcohol on guinea pigs 

 are inherited through two or more generations. 

 In man alcohol may have an "induction" effect 

 on offspring, but it does not seem to alter 

 hereditary constitution. Probably of a similar 

 character are Sumner's results; he found that 

 mice raised in the cold have shorter tails than 

 those raised at higher temperatures and this 

 modified character appears in the next genera- 

 tion. If this is an after effect or "induction" it 

 should disappear in following generations. 



Kammerer found that black and yellow 

 spotted salamanders reared on yellow soil 



