Anatomy. — "7%^ Problem of Orthognathisin" . By Prof. L. Bolk. 

 (Communicated at the meeting of October 28, 1922). 



In the meeting of February 1921 I called attention to the fact 

 tliat the typically somatic human features are of a special character, 

 viz, they are persisting fetal properties and conditions. I referred 

 this fact to the influence of the endocrin system, which, through its 

 inhibitive action, fixes fetal morphogenetic relations. The character 

 of the human body, thei-efore, is its fetality, and this character 

 results from what 1 am inclined to term a process of fetalization. 



When studying the structure of the human skull from this point 

 of view, it is surprising to note how all at once the whole complex 

 of the typically human features, — and there are many in the skull 

 — becomes easy of comprehension. Of all parts of the human body 

 the head is most indicative of its fetal character. Earlier researches 

 made by me had already favoured this view with regard to several 

 of these properties. Long before conception of the fetalization-prin- 

 ciple as the leading factor in the genesis of the human body as a 

 whole, I had already pointed out that many somatic property 

 of man represents an early stage of ontogenetic development. 



However, there was one property of the skull about which 1 had 

 no fixed opinion, and it is just this property that determines so 

 emphatically the human physiognomy viz. its orthognathism. The 

 question urged itself upon me, whether also this feature should be 

 a persisting fetal property? I felt some diffidence in putting the 

 question, as the pronouncements laid down in the literature were 

 not very encouraging, the general conception being that the ortho- 

 gnathous (i.e. the human) skull-type has originated from the pro- 

 gnathous (i.e. the animal) type. The evolution is supposed to have 

 consisted in a shortening of the jaws, in connection with the 

 presumed reduction of the set of teeth. Now, to this conception 

 objections might be raised also from other quarters, but 1 deemed 

 it necessary, instead of opposing one speculation to another, to let 

 the facts speak for themselves. This led me to an inquiry into the 

 relation between prognathism and orthognathism. The results were 

 indeed surprising, for not only was I in a position to establish this 

 relation, but it also became evident that the whole complex of 



