Characters, Hereditary and Acquired. 121 



added that there is here no measurable possibility 

 of accidental coincidence (seeing that normal guinea- 

 pigs do not seem ever to produce young with any 

 deficiency of toes), while the only possibility of 

 mal-observation consists in some error with regard 

 to the isolation (or the tabulation) of parents and 

 progeny. Such an error, however, may easily arise. 

 For gangrene of the toes does not set in till some 

 considerable time after division of the sciatic nerve. 

 Hence if the wound be healed before the gangrene 

 begins, and if any mistake has been made with re- 

 gard to the isolation (or tabulation) of the animal, it 

 becomes possible that the latter should be recorded 

 as an uninjured, instead of an injured, individual. On 

 this account one would like to be assured that 

 Brown-Se*quard took the precaution of examining 

 the state of the sciatic nerve in those comparatively 

 few specimens which he alleges to have displayed 

 such exceedingly definite proof of the inheritance 

 of a mutilation. For it is needless to remark, after 

 what has been said in the preceding chapter on the 

 analogous case of epilepsy, that the proof would 

 not be regarded by any physiologist as displaced 

 by the fact that there is no observable deficiency 

 in the sciatic nerve of the toeless young. 



8th. Appearance of various morbid states of the skin and 

 hair of the neck and face in animals born of parents having had 

 similar alterations in the same parts, as effects of an injury to 

 the sciatic nerve. 



I have not paid any attention to this paragraph, 

 because the facts which it alleges did not seem of 

 a sufficiently definite character to serve as a guide to 

 further experiment. 



