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also of apes. It is only gradually, that in the ape-foetus and the 
young ape-child, the jaws extend forward. In man this growth is 
ugain suppressed, he retains his foetal character. And this retardation 
also takes place under the influence of hypophysis. For we know 
that when this organ is affected, both jaws, but particularly the 
lower jaw can enlarge considerably ; the suppressing influence there- 
fore, which proceeded from this organ — and which, in normal 
circumstances, keeps this potentiality of development in a latent 
condition, for the whole of life — is removed, and the old pithecoid 
factor of development tries to re-assert itself. Not only, however, 
for the jaws, also for the frontal-ridges. Do not many historia morbi 
of such patients mention a gradually stronger development of these 
ridges ? 
Not all human races however are equally orthognathic ; the stronger 
prognathy of the “black” races is well-known. From this it might 
be inferred that that suppressing influence acted less strongly in the 
latter races than in the white ones. This assertion is supported by 
another character to which I want to draw your attention, viz. the 
colour of the human skin, and especiably that of the white races. 
The colour of the skin is defined by the development to a more 
or less degree of the so-called skin-pigment. This is developed in all 
Primates, and as regards man, particularly in the black races. So 
the hardly if at all pigmented skin of the white races has again 
been brought about by a retardation or suppression of the develop- 
ment of skin-pigment. And here again we have a persistence of a 
foetal character. The white skin of man, therefore, is not a new- 
acquired property, for it is a condition found temporarily in all 
fetal primate individuals, the further developmental phase, which 
follows in the other Primates and also in the black races, being 
suppressed in the white races. And that this influence is active 
already in negroes, is evident from the fact that negrochildren are 
born with a white skin, and only become black shortly after birth. 
Therefore the white has, in a way, retained a foetal character, which 
the negro has lost, consequently the retardation process in the 
white is stronger than in the black, in complete accordance with 
what could be ascertained with regard to the development of the 
jaws. So human evolution has, at least with regard to the morpho- 
logical properties, progressed further in the white race than in the 
black races. How far the same applies to the mental qualities may 
here be left out of discussion. 
So the whiteness of the human skin is again an instance of 
retardation. Which endocrine organ is responsible here? To this 
