OBSERVATIONS AND EXPERIMENTS 213 



hereditary transmission .of an acquired character, but 

 as the disease may havtf had a chemical or microbian 

 origin, this case is open to the objections we mentioned 

 before. 



A classical example cited and discussed in all the 

 literature on the subject is the case of Brown- Se- 

 quard's guinea-pigs. For a number of years, from 

 1869 to 1891, he experimented on thousands of these 

 animals and determined in them a certain form of 

 epilepsy through certain operations on the nerves, 

 cross hemisection of the spinal cord or section of the 

 sciatic nerve. In certain cases the young were 

 affected with the same form of epilepsy. The results 

 of these experiments have since been confirmed by 

 other scientists and brought into dispute by others. 



Weismann makes the suggestion "that, during or 

 after the operation, some kind of pathogenic micro- 

 organism might easily reach the wounded parts, and 

 there excite inflammation which may extend centrip- 

 etally to the brain. 2 There is no evidence that such 

 a supposition is well founded but other objections 

 have been presented. Guinea-pigs are strongly pre- 

 disposed to epilepsy and therefore the results of 

 Brown- Sequard's experiments might be a pure coin- 

 cidence or they might be due to the transmission of a 

 chemical substance. This last suggestion was made 



2 A. Weismann. The Evolution Theory, Vol. II, p. 67. 



