2 26 TRANSMISSION OF ACQUIRED CHARACTERS 



occurred in every generation, and one of which no inherited results 

 are known. Like circumcision, it is in one respect not a quite 

 satisfactory negative case, being limited to one sex. Among savage 

 peoples, however, ear-boring, nose-boring, and the like, have been 

 practised by both sexes for many generations ; and it need hardly 

 be said that no inherited result has ever been observed. 



Casual Wounds. — Darwin cites the case of a man whose thumbs 

 were badly injured in boyhood, as the result of frost-bite. His 

 oldest daughter (S) had thumbs and thumb-nails like the father's ; 

 his third child was similar as to one thumb ; two other children 

 were normal. Of the four children of S, the first and the third, 

 both daughters, had deformed thumbs on both hands. The cogency 

 of this case depends on whether there was or was not any previous 

 family tendency to thumb-deformity. It may have been that the 

 frost-bite was really an unimportant incident. Darwin gives 

 another case of a man who, fifteen years before marriage, lost his 

 left eye by suppuration. His two sons had left-sided microphthal- 

 mia. Here we have probably to deal with an innate eye-defect 

 in the father. 



Bouchut * reports the case of a man of twenty-five who injured 

 his hands and feet by a fall from a scaffold. Of five children only 

 one was normal. His son had one finger on each hand and two 

 toes on each foot. A daughter (M) had two toes on each foot, one 

 finger on the right hand, and two on the left. She married a normal 

 man, and of her four children the oldest was normal, the others 

 like herself. 



Cases like the last may seem puzzling to those unaccustomed to 

 deal critically with the facts of inheritance. But in reality they 

 are in most cases merely illustrations of the familiar fallacy of con- 

 fusing post hoc and propter hoc, of mixing observation and inference 

 (Ziegler, 1886, p. 26). Bouchut does not say that the children 

 showed the same deformity as their father acquired ; he does not 

 tell us about the ancestry of the father and mother, an indispensable 

 fact if a case is to be considered seriously, since inborn mal- 

 formations are common in some families ; finally, the frequency 

 of inborn malformations of the fingers and toes must be borne in 

 mind, and the possibility of coincidence allowed. 



Ziegler (1886, pp. 29, 30) discusses a number of cases where defects 



* Nouveaux i^lements de Pathologie generate, Paris, 1882. Cited by 

 Ziegler, 1886, pp. 3, 4. 



