HEREDITY 2 25 



anatomical types of people and trying to correlate with these the diseases 

 from which they have suffered. The recent work of Draper who ap- 

 proached the question by taking typical cases of certain diseases and study- 

 ing the physical conformation seems to promise more definite results. Of 

 similar import and carrying even greater suggestion of future interest are 

 observations indicating that the blood grouping, a functional inheritable 

 manifestation developed under definite conditions between the blood cells 

 and the blood serum, is associated in the inheritance with the natural im- 

 munity to diphtheria toxin or with the capacity to be immunized against 

 this poison. 



Our general culture, our freedom from certain infectious diseases may 

 alike be immediately and largely a matter of social inheritance. Our lia- 

 bility to those diseases, defects, and discomforts which are controlled by 

 the physical inheritance must always be based directly on the qualities of 

 the germ plasm transmitted from father and mother to their children and 

 so to their grandchildren. 



We can perhaps sterilize certain obvious defectives and so minimize 

 the economic burden imposed by the maintenance of institutions for their 

 care. But we cannot so durably solve the problems imposed by the fact 

 that disabling defects, diseases and tendencies to the development of 

 disease are inherited. The faulty germ plasm considering the multitude of 

 distorted conditions is too widespread for this. The ancients when they 

 wished to completely subjugate a conquered enemy people "decimated" 

 the population. This seems to be the ultimate which cold-blooded im- 

 mediate destructive human purpose can achieve. It is doubtful if we shall 

 ever be persistent enough to interfere radically with the propagation of 

 lo per cent, of the defectives even in cases where there is complete agree- 

 ment as to the need for such measures. 



Recognizing the wide distribution, the completely individualistic char- 

 acter of the faults in the germ plasm, it seems that most rapid progress can 

 be made through the development of the individual understanding and 

 conscience. The appeal to family pride has been a most potent force in the 

 past, and one which it may be feared the present unduly loses sight of. 



Family pride is likewise regarded as undemocratic. But in terms of gen- 

 erations we can pass to our descendants as we choose a democracy of the 

 unfit or one of the highest personal and social accomplishment. To the 

 development of this end the study of the detailed manner in which dis- 

 eases or the influences controlling disease incidence are transmitted in in- 

 heritance is likely to prove an increasingly useful and stimulating force. 

 At present and doubtless in the end the practical guide to individual judg- 

 ment would appear to lie in the stem of longevity. A short lived strain may 

 be fundamentally healthy, a long lived one must be at least superior. When 

 this complex of physical attributes is balanced with the knowledge of the 



