TRANSMISSION OF MODIFICATIONS 367 



The most direct way of procedure is, however, not to endeavor 

 to eliminate the law of chance, but, by direct experiment, 

 to learn whether a sufficient number of occurrences can be 

 established to clearly exceed in number any possible coincidence. 



Experimental evidence on inheritance of mutilations. The 

 facts just given show conclusively the hazard of framing theories 

 on chance occurrences, and demonstrate the practical worthless- 

 ness of all but experimental evidence in the study of inheritance. 



Unfortunately but little evidence of this kind is at hand, and, 

 so far as is known to the writer, that which is at hand is confined 

 to artificial injuries to the nerve, with exception of that already 

 cited in such practices as docking and circumcision. 



Romanes outlines seven classes of abnormalities that appeared 

 in the offspring of guinea pigs corresponding to those artificially 

 produced in the parents by Brown-Sequard and his assistants. 

 They are in brief as follows : 1 



1. Appearance of epilepsy, when parents have been rendered 

 epileptic by an injury to the spinal cord. 



2. Same, when the injury had been to the sciatic nerve. 



3. Change in the shape of ear in animals born of parents in 

 which such a change was the effect of a division of the cervical 

 sympathetic nerve. 



4. Partial closure of the eyelids in young born of parents in 

 which that state of the eyelids had been induced by section of 

 the cervical sympathetic nerve or the removal of the superior 

 cervical ganglion. 



5. Exophthalmia in young born of parents in which a similar 

 protrusion of the eyeball had been produced by injury to the 

 restiform body. 



6. Gangrene of the ears in animals whose parents' ears had 

 been affected by injury to the restiform body. 



7. Absence of toes in young whose parents had eaten off 

 their toes, which had become " anaesthetic " by reason of the 

 section of the sciatic nerve alone or of that nerve and the crural. 



8. Various morbid states of the skin and hair corresponding 

 to a similar condition of the parents which had been brought on 

 by an injury to the sciatic nerve. 



1 Romanes, Darwin and After Darwin, II, 103-122. 



