1911.] the Transmission of Acquired Characters. 561 



As it might be argued that bacterial infection from the raw surface may- 

 be the primary cause of the appearance of the condition, it is interesting 

 to enquire whether the phenomenon may appear in the absence of this 

 41 trophic " change. 



In illustration of this the three following experiments may be quoted : — 



Guinea-pigs 60, 61, 63. — These three animals had a portion of their right 

 great sciatic nerves removed on June 11, 1909. In each case the "incom- 

 plete " reaction of the Brown-Se'quard phenomenon appeared on or before 

 July 10, 1909. Two days later records of the movements of the hind limbs 

 were recorded. At that time there were no traces of " trophic " change in 

 the right foot of 60. In the case of 61 there was only a slight change 

 in one claw, and in the case of 63 there was a well-marked " trophic " change 

 •of the right foot. There was no very great difference between the records 

 taken from the three animals. The best records were obtained from 60 and 63. 



These experiments seem to prove that the presence or absence of a 

 " trophic " change in the foot is not a determining factor in the production 

 of the phenomenon. 



In connection with the " trophic " changes in the foot, another observation 

 may be recorded. The change is in great part due to the habit of nibbling 

 the anaesthetic parts. This may be regarded as a morbid habit. Not only 

 does a guinea-pig nibble its own foot, but it may nibble the foot of another. 

 Protective reflexes prevent this from being effective when that other animal 

 is normal. But if it, too, have its foot rendered anaesthetic by section of 

 the great sciatic nerve, then the nibbling may be effective in destroying 

 part of the foot. Thus it has been noticed that if two such individuals be 

 kept in the same cage, it sometimes happens that they will not only nibble 

 their own feet, but will also nibble each other's feet. This acquired habit, 

 then, may lead a guinea-pig to the unnatural act of devouring others of its 

 own kind, and may explain in part the greater than normal destruction of 

 young by the mother in the case of such individuals. 



(c) Occurrence of the Phenomenon in Relation to Changes in the Great Sciatic 

 Nerve. — When the great sciatic nerve is severed and a portion removed, 

 regeneration does not occur, and the central stump forms a bulbous enlarge- 

 ment. It might reasonably be argued that a continued irritation arising in 

 this stump might be the cause of the production of the phenomenon. To 

 investigate this point the nerve, in a guinea-pig which demonstrated the 

 phenomenon, has again been cut central to the first lesion. 



Guinea-pig 21. — In this experiment the great sciatic nerve was divided 

 and a portion removed on January 8, 1909. This lesion was made at the 

 level of the middle of the thigh. In the beginning of July of the same 



