Monstrosities 401 



that some internal hereditary quality is pres- 

 ent, though often latent, and that the observed 

 anomalies are to be regarded as responses 

 of this innate tendency to external con- 

 ditions. Our two types differ in the frequency 

 of these responses. Rare in the poor race, they 

 are numerous in the rich variety. The external 

 conditions being the same for both, the heredi- 

 tary factor must be different. The tendency is 

 weak in the one and strong in the other. In 

 both cases, according to my experience, it may 

 be weakened or strengthened by selection and 

 by treatment. Often to a very remarkable de- 

 gree, but not so far as to transgress the limits 

 between the two races. Such transgression 

 may apparently be met with from time to time, 

 but then the next generation generally shows 

 the fallacy of the conclusion, as it returns more 

 or less directly to the type from which the strain 

 had been derived. 



Monstrosities should always be studied by 

 physiologists from this point of view. Poor 

 and rich strains of the same anomaly seem at 

 first sight to be so nearly allied that it might be 

 thought to be very easy to change the one into 

 the other. Nevertheless such changes are not 

 on record, and although I have made several at- 

 tempts in this line, I never succeeded in passing 

 the limit. I am quite convinced that sometime 



