ACQUIRED AND ABNORMAL CHARACTERS. 63 



nothing is detected but a cicatrix in the envelopes of 

 the spinal cord, which appears a little thickened at 

 that point ; but the nervous tissue itself does not dif- 

 fer apparently from surrounding elements of the same 

 nature and structure. 



" If an examination is also made of one of the 

 young, nothing at all is discovered. 



" These young can be allowed to breed in-and-in, 

 and always the same phenomena will be observed in 

 each subsequent generation. 



" I have sometimes noticed that if a male or a fe- 

 male belonging to any one of the successive genera- 

 tions is allowed to breed with another healthy animal, 

 very generally some of the young present the same 

 hereditary peculiarities. I have followed animals thus 

 operated upon through seven generations." 1 



In the experiments of Dr. Brown-Sequard with 

 Guinea-pigs, it was found that an injury of the spinal 

 cord, or of the sciatic nerve, produced a change in 

 sensation over a certain well-defined area of the face, 

 in addition to the epileptic affection already referred 

 to. When the sciatic nerve was the seat of the injury 

 the outer part of the foot was likewise destroyed, 

 leaving but one toe, the inner, on the foot of the in- 

 jured side, and this deformity is a permanent one. 



When the animals recover from the epileptic affec- 

 tion, as they do after several months, " all the phe- 

 nomena observed about the zone of skin in the neck 

 and face recur in the reverse order ; that is to say, all 

 the different sensations return by degrees, at the same 

 time that the hair of the region falls, and new hair 



1 Popular Science Monthly, July, 1877, pp. 334, 335. 



