No.561] THE NINE-BANDED ARMADILLO 



vidual. In other words, these quadruplets resemble one 

 another as closely as do the rig-lit and left sides of single 

 individuals. One might readily make the claim that the 

 quadruplets are simply four parts of one individual, 

 since they have been derived by a process of asexual 

 budding from a single embryonic vesicle. The closest of 

 ordinary blood relations have coefficients of correlation 

 of a decidedly lower order, that of brothers being about 

 0.5; hence the polyembryonic relation is much closer 

 than a mere fraternal one. We may conclude then that 

 the predetermining mechanism works accurately up to 

 from 91 to 98 per cent, and that epigenetic disturbances 

 or inequalities effect alterations in the end result ranging 

 from 2 to 8 per cent. One of the most fundamental 

 postulates of the sciences of taxonomy and phylogeny is 

 to the effect that degrees of resemblance are criteria of 

 blood relationship. This postulate is strongly supported 

 by the facts just given, since the closest resemblances 

 ever found to exist between individuals are here the 

 result of the closest possible blood relationship; for no 

 closer genetic relationship could well be conceived than 

 that involved in the known origin of these armadillo 

 quadruplets. 



A subsidiary question arises as to what kind of epi- 

 genetic factors operate in inducing dissimilarity among 

 the polyembryonic offspring of a set. Studies of the 

 heredity of certain characters and of the distribution of 

 certain units among the quadruplets lead to the conclu- 

 sion that the most important differences are due to im- 

 perfections in the mechanism for distributing germinal 

 materials, a mechanism which has visible expression in 

 the mitotic complex of cleavage. It seems probable that 

 certain materials which condition the development of 

 certain characters are not distributed with exact equality 

 to the first two blastomeres. This would make one half 

 of the embryonic vesicle different in potentiality from the 

 other. A similar inequality might exist in the second 

 cleavage and in subsequent cleavages. Mere difference> 



