Anatomy. — ''Complicated Mendelian segregation in the here- 

 dity of head/orm in man." By G. P. Frets. (Communicated 

 by Prof. C. Winkler.) 



(Communicated in the meeting of November 24, 1917). 



In a first communication on this subject, it appeared that some 

 factors working in the same direction, as it has been deduced by 

 Nilsson-Ehle from his experiments for the heredity of characteristics 

 of cereaiia, and has been proved by further cultures, can likewise 

 explain in different regard the motion of heredity' in our material. 

 The exceptions, however, that Nilsson-Ehle himself found, and that 

 compel to accept still special hypotheses, the complications that are 

 clearly shown by animal material also, as is clearly proved by the 

 experiments of Davenport, and induce us e.g. to the introduction of 

 the notion of potency of factors of heredity, and reversed predo- 

 minance, compel us to examine if this is likewise the case for our 

 material. This must, however, be preceded by the consideration, if 

 perhaps the difficulties that our results contain for the purely 

 Mendelian explanation, result from the suppositions that formed the 

 basis of our investigation. 



Hitherto, namely, we have investigated if the shape of the head, 

 consequently the index, follows the rules of segregation of IVJendei,; 

 it is however also possible that the shape of the head is a compli- 

 cated property, and length and width mendel separately. We 

 intend to examine this iiow : the difficulties for the explanation, 

 e. g. the contradictions of table IV and table V might be explained 

 by it. 



If the length and the width mendel separately, the combination 

 of the length of the father and the width of the mother, or the 

 reverse, might cause a strongly deviating shape of the head. A 

 perusal of the values of the head in table I of the cases that 

 have been collected already in table II teaches that this simple 

 possibility is in general not realized in the inheritance. 



There is however more. The brachy cephalic shape of the head 

 can come into existence in two ways, namely by shortening and 

 by vi'idening. In the material treated here by far the greater part 

 of the heads with a high index are short heads. The few wide 



