SOME POSSIBLE BEARINGS OF GENETICS ON PATHOLOGY 23 



both in the normal hen and in hen-feathered cocks, we have a com- 

 plete explanation of all the facts. This explanation is made more 

 probable by the results of removing the ovary of the hen, when, as 

 Goodale has shown, the spayed hen develops the full male plum- 

 age of her breed. Since the luteal cells are present in the hen and 

 in the hen-feathered cock, and are absent in the adult cock-feach- 

 ered male, it seems not a far-fetched hypothesis to assume that 

 these cells (or their secretions) are those involved. 



The next illustration carries us into a more debatable field. 

 Many human defects are connected with the nervous system, and 

 it is interesting to find that many of them are believed to be in- 

 herited; even when no corresponding structural basis in the brain 

 can be made responsible for the defect. 



Feeblemindedness, insanity, and even some types of crimi- 

 nality have been said to be inherited according to a simple one- 

 factor Mendelian difference. Owing to the difficulty of diagno- 

 sis it is obvious that the student of genetics would be expected to 

 approach these problems with the utmost caution. The data, on 

 which some rather sweeping conclusions have been based, some- 

 times show, on closer scrutiny, obvious contradictions. Take, 

 for example, the case of feeblemindedness which has been repre- 

 sented as though it differed from the normal (whatever that may 

 be ) by a single Mendelian factor difference. The evidence for 

 this is far from convincing, and all that can be safely said, I think, 

 is that there are types of imbecility that may possibly be due to 

 multiple factors, but until the relation of imbecility to various 

 disorders of the glands and to syphilis has been thoroughly 

 studied, even my cautious statement may seem to go too far. 

 Curiously enough no one has as yet had the temerity to suggest 

 that some of the high-grade imbecile types— the moron, for ex- 

 ample—might represent an ancestral stage of the human race. If 

 this were true, intelligence would then be looked upon as an inno- 

 vation in the race, that has not yet spread to all of its members. 

 I am aware that a similar suggestion has been made with respect 

 to the criminal. Lombroso's " criminal type " is notorious. The 



