1911.] the Transmission of Acquired Characters. 



571 



reflex. And Mayer (33) found that the spinal cord was especially excitable 

 on the injured side after section of one great sciatic nerve. 



If the afferent impulses normally carried to the spinal cord through the 

 great sciatic nerve tend in their activity to depress the excitability of the 

 scratch-reflex, the causation of the Brown-Sequard phenomenon by the 

 section of a great sciatic nerve resolves itself into the raising of the 

 excitability of the scratch-reflex by the removal of an inhibitory influence. 

 The fact that the phenomenon does not at once appear on section of the 

 nerve may be explained by a condition analogous to spinal shock. 



V. Experiments on Transmission of the Phenomenon. 



(a) Experiments on Guinea-pigs. — In the present experiments 29 young 

 guinea-pigs have been born of 11 female guinea-pigs after removal of a part 

 of the mother's right great sciatic nerve. Some of these were conceived by 

 normal fathers before the operation. In the case of the others, both parents 

 had their sciatic nerves cut. As in no case any congenital abnormality of the 

 hind limbs was observed it is unnecessary to give further details. 



Of these young guinea-pigs only five survived birth. One of the five was 

 born within a short period of the operation, and before the mother had 

 exhibited the phenomenon. The others were born in the third month 

 after the operation, and when their parents exhibited the phenomenon. 

 In none was there any malformation of the feet or toes, and there was 

 no evidence of the presence of the phenomenon, although they were tested 

 over periods of several weeks (the one which was born soon after the 

 operation lived only two days, the other four lived for 7, 7, 26 and 28 weeks 

 respectively). 



Of the remaining 24 guinea-pigs all were dead at birth, or died within 

 a few hours of birth ; five were born prematurely ; five were not damaged 

 by the mother ; the remaining 14 were all partially eaten. In some cases 

 they were almost entirely devoured, in others scarcely touched. 



No part of the body was exempt, although the parts usually damaged 

 appeared to be the abdomen and limbs. In several cases the limbs were 

 undamaged, but in four cases the hind limbs alone were injured. 



These four instances bear on the present problem. In two cases the hind 

 leg was eaten. In one case, one foot was eaten and nothing else; and, 

 in the fourth case, only one toe of one hind limb was devoured. Had 

 this last guinea-pig survived, and not been examined until the toe had 

 healed, the malformation might well have been regarded as congenital. 



(b) Experiments on Bats. — A portion of the right great sciatic nerve has 

 been removed from 12 rats. Some of these were white rats, and others 



