io6 The Third and Fourth Generation 



The most noted experiment that seems to 

 give support to the notion that acquired 

 modifications are inherited is the experiment of 

 Brown-Sequard with guinea-pigs. Brown- 

 Sequard so injured the nervous system of adult 

 guinea-pigs that they had frequent epileptic 

 seizures. It was found that the offspring of 

 these animals also had much more frequent 

 attacks of epilepsy than the offspring of normal 

 pigs. But this experiment lacks confirmation. 

 It has been tried by later experimenters without 

 achieving the results that Brown-Sequard 

 claims. 



The first serious doubt of the inheritance of 

 acquired characters was raised by Weismann 

 in the latter part of the last century. Weis- 

 mann, in his study of some of the lower animals, 

 was struck by the fact that those cells in the 

 animal body which ultimately give rise to the 

 eggs or the sperm seem to have a history that 

 is more or less disconnected from and inde- 

 pendent of the rest of the organism. We have 

 already seen that any animal or plant originates 

 from one single cell; that by repeated divisions 



