PAPERS OF GENERAL INTEREST 63 



that they do increase in mental power, statements to the 

 contrary notA\'ithstanding, 



The "dojDe fiend" will take a quantity of poison large 

 enongh to kill several men who are not accustomed to 

 taking it. The man who survives the taking of such 

 large doses does not do so because he was born ^^i.th 

 greater powers of resistance to that drug than other men. 

 He does so because he began with small doses, such as 

 any man might take and survive, and then gradually built 

 up his powers of resistance by continually exercising 

 them. By exercising the powers he has, a man can build 

 up powers he did not have before, and powers which 

 never existed in any ancestor. 



By beginning with small doses and gradually increas- 

 ing them, pigeons have been made resistant to rattlesnake 

 poison. Eesistance has been built up in this way until 

 pigeons were able to withstand a dose more than four 

 times as powerful as that which would kill in the first 

 place. By exercising the feeble powers which they had, 

 these pigeons acquired powers which they did not have 

 before, and powers which never existed in any ancestor. 



Let us turn aside and consider the powers of plants, 

 because the matter under consideration is something 

 fundamental in living things. If we take some wild plant 

 and attempt to reproduce it by cuttings, we are likely to 

 find that it can be reproduced that way only with diffi- 

 culty. But if we take a cutting from the first plant raised 

 that way we find the second time it grows a little more 

 readily. If we take a cutting from the second plant to 

 raise a third, we again find it starts more easily, and so 

 on time after time. By many repetitions the plant de- 

 velops the power of producing roots abundantly from 

 cuttings. By exercising the powers which it has it ac- 

 quires powers which it did not have before, and powers 

 which never existed in any ancestor. 



There is no selection in this matter. Xo seeds are pro- 

 duced. The final plant is really a developed section of 

 the origmal plant, but has powers which the original plant 

 did not have. A large number of our greenhouse plants 



