$8 THE TREND OF THE RACE 



uct of specific neurotoxins, it is at present impossible to say. 

 There is little in the symptoms of insanity that would lead us to 

 conclude that it is the expression of mere weakness or lack of 

 something, any more than is rheumatism or the gout. 



It is one of the unfortunate influences of the presence-absence 

 theory that it leads people to jump to the conclusion that traits 

 may be due to absences and hence recessive when there is no clear 

 evidence of this from the facts in hand. Imperfect dominance is 

 sufficiently plentiful among organisms in general to make us 

 expect it more or less frequently in the inheritance of neuropathic 

 traits. Davenport and Weeks, as we have seen, conclude that it 

 occurs in the transmission of epilepsy and related neuroses. An 

 examination of the charts in Rosanoff and Orr's paper on the 

 inheritance of insanity shows that all the facts may plausibly be 

 interpreted according to the same hypothesis. The frequency 

 with which the matings of normal and neuropathic parents 

 produce neuropathic offspring is rather better in accord with this 

 view. On the assumption of complete recessiveness Rosanoff and 

 Orr are led to the view that over 3 1 per cent of apparently normal 

 people are carriers of neuropathic defect. In most of the cases 

 given by Rosanoff and Orr where the mating of a normal and a 

 neuropathic resulted in neuropathic offspring, it was not possible 

 to show that the normal parent was in fact heterozygous; he was 

 simply assumed to be so on account of the character of the off- 

 spring. It is evident that if neuropathic traits are imperfectly 

 dominant, or not completely recessive (which is the same thing) 

 it is not necessary to assume that the heterozygous condition is 

 nearly so prevalent. Matings of apparently normal stock with 

 one that is neuropathic are so often followed by unfortunate 

 results that one is naturally led to suspect that a partial blending 

 or direct contamination, is a phenomen of common occurrence. 



THE ALLEGED PRINCIPLE OF "ANTEDATING" OR "ANTICIPATION" 



Dr. F. W. Mott has pointed out what he considers to be a 

 principle of general application in neuropathic inheritance, 



