338 Adaptation to Environment 



dary sexual character in the male with its different 

 breeding habit. Kammerer now forced such toads to 

 copulate in water instead of on land (by keeping the 

 animals in a terrarium with a high temperature). He 

 makes the statement that by forcing the parents to 

 lay their eggs during successive spawning periods in 

 water he finally obtained offspring which under normal 

 temperature conditions lay their eggs naturally in 

 water; in other words, they have changed their habits. 

 We will not discuss this part of his statement since 

 the breeding habits of animals in captivity are liable 

 to be abnormal. But Kammerer makes the further 

 important statement 1 that the male offspring of such 

 couples will in the third generation produce the swell- 

 ing on the thumb and the usual roughness, and in 

 the fourth generation black pads and hypertrophy 

 of the muscles of the forearm will appear. In other 

 words, he reports having succeeded in producing an 

 inheritance of an acquired morphological character 

 which has never been known to occur in this species. 

 Bateson, on account of the importance of the case, 

 wished to examine it more closely and I will quote his 

 report. 



The systematists who have made a special study of 

 Batrachia appear to be agreed that Alytes in nature does 

 not have these structures; and when individuals possessing 

 them can be produced for inspection it will, I think, be time 



1 Kammerer, P., Arrh.f. Entwcklngsmech., 1909, xxviii., 448. 



