14 THE AMERICAS S A TC RACIS T | Vol. XIA'J 



W react and are destroyed, the F, generation is white — 

 this time albinic white, mutants. W and N both being 

 destroyed, these animals are nulliplex and breed accord- 

 ing to the familiar formula. 



As still another alternative, let W exist in still larger 

 quantities and the mating take place ; not only is all of 

 N destroyed but there is an excess of W which gives 

 some areas of duplex dominant white not holding the 

 pigmented color as a recessive trait — in quite the same 

 manner as the Shorthorns designated in this study as 

 type No. 9 possess a coat solid white, some areas of 

 which are dominant white not covering the red and the 

 remainder of the areas are albinic white. A still greater 

 amount of W will apparently effect the total destruc- 

 tion of N, making the offspring in the entire coat duplex 

 dominant white, not holding N latent in the gametes and 

 not capable of " reversion. ? - 



Let the antibody exist in very small quantity, insuffi- 

 ciently large to inhibit the ontogenesis of N, and let fer- 

 tilization take place. It is conceivable that the antibody 

 in such small quantity might have the same effect upon 

 N as alcohol has upon an enzyme, in which case N would 

 play its usual part in ontogenesis, but, being constantly 

 harassed by W, would finally be inhibited or destroyed. 

 The F x generation would then show senile grayness, as 

 in man; here again the most superficial tissues are first 

 attacked. If the antibody (W) is a trifle more concen- 

 trated the F generation will be born pigmented, but will 

 develop juvenile white, as with the white horse, which 

 as previously described is born with pigmented hair 

 and skin — the skin remaining black and the hair turning 

 white. Thus the process seems to be progressive, de- 

 pending upon different intrusions de novo — "muta- 

 tions" — and different inheritance lines for the pre- 

 sentation of various quantities of the antibody effecting 

 the destruction of N in a definitely progressive onto- 

 genetic, area and tissue sequence. 



This is the hypothetical picture of intra-zygotic reaction 



