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or suppressing activity of the endocrine organs, and that, in case of 
affection or abnormal development of those organs that suppressing 
influence is lost, so that the modifications which then appear in 
the body, have a pithecoid character. 
I hope further to draw your attention to phenomena from which 
we may conclude that that retardative influence not only corcerns 
the merely morphological faculties, but that the entire process of 
development, the developmental rate of the human individual, as 
compared to that of the other Primates, is retardated. 
One of the first characteristics by which man is distinguished 
from all other Primates is his hairlessness. On the cause of this 
Darwin is not always of the same opinion. At one time he is inclined 
to consider the nakedness of man as the result of sexual selection, 
at other times he leaves scope for the possibility of climatological 
influences, having been at work. I have no space for a criticism 
of these opinions. I shall restrict myself to the observation that 
the foetus of all Primates is hairless and that therefore, in the 
genesis of man, the part played by the endocrine organs consisted 
in suppressing the potentiality for hair-development, with the exception 
of that part of the skin which covers the skull. The hairlessness 
of man is therefore the persistance of a foetal character. It is a 
well-known fact that now and then this suppressing influence on 
the development of the hair-covering is removed and individuals are 
born with a more or less complete hair-coat, the so-called hair-men. 
Which of the endocrine organs was it, that had a suppressing 
influence on the formation of the hair-covering in man? We can 
indicate it with a good deal of certainty. This organ is the Hypo- 
physis. For we know that with hyperfunction of this organ in man 
as well as in woman, a hair-covering may be developed in an 
extremely strong degree, so that the limbs and trunk in particular 
are thickly covered with long hairs. 
So we have here our first instance of an affection of an endocrine 
organ influencing a specifically human character, and that in such 
a way, that a pithecoid condition returns. However, an affection of 
Hypophysis is present in yet another series of phenomena, which bear 
the same character and manifest themselves in particular at the skull. 
The skull of apes, especially of anthropoids, is distinguished from 
man’s, by the marked development ef the jaws, the so-called supra- 
orbital-ridges also attaining an extraordinary size. The anthropoids 
are what is called markedly prognathic, man is orthognathic, whereas 
his supraorbital-ridges have hardly come to any development at all. 
Again orthognathy is a foetal character, not only of man, but 
