88 Disease and Immunity 



Davenport and Neal raised three lots of 

 stentors, — one in pure water and another in a very 

 weak solution of corrosive sublimate. After two 

 days both lots were put into a killing solution 

 which was twenty times as strong as the weak 

 solution. Those raised in pure water died in 83 

 seconds, while those raised in the weak solution 

 lived for 304 seconds, or nearly four times as 

 long. No deaths occurred in the weak solution, 

 but the animals there had to exert themselves to 

 resist the action of corrosive sublimate, and in 

 doing this they acquired powers they did not 

 have before, and powers which never existed in 

 any ancestor. The third lot was kept in a solu- 

 tion twice as strong as the weak one, or one- 

 tenth of the strength of the killing solution. 

 These last died more quickly than those raised 

 in pure water. 



Here we have a case of one lot of stentors sub- 

 jected to a load whidi was within the powers 

 they had originally, and another lot subjected to 

 a load which was in the nature of an overload. 

 When the load was greater than anything to 

 which they had been subjected before, but was 

 within their powers, those powers were built up 



