874 



greater potency of the factors of heredity we might admit here also 

 a separate factor of intensity. 



As summary and conclusion we premise now that in our material the 

 great line of Mendelism is to be recognized. There are distinct in- 

 dications of segregation and of independency of factors of hereditj>. 

 With regard to the nature and the number of the factors of here- 

 dity the phenomena of segregation are too much complicated 

 for us to be able to give a sufïicient explanation by admitting one 

 pair of factors of heredity, (brachycephaly — dolichocephaly). One 

 pair of factors of heredity for the length, and one pair for the width, 

 that segregate independently of each other are insuflicient for the 

 explanation. We have therefore tested the data by the scheme of 

 heredity of Nilsson-Ehlk, in which some factors working in an 

 equal sense are admitted. Here there are also two possibilities viz. 

 some factors for the shape of the head, or some factors for the 

 length and for the width of the head. We have admitted the latter 

 possibility with the addition, that the factors for length and width 

 are coupled; there is thus a preference for special combinations of 

 factors. There is likewise some dominance of the large dimensions 

 over the small ones. The short, small head shows distinctly recessivity, 

 is moreover hypostatic with regard to the large, wide head. 



At the occurrence of different proportions in different cases of 

 the same indices, also when they relate to the same dimensions, 

 we must always consider, that a special value is the expression of 

 modification (not inheritable variation), of exterior influences (ill- 

 ness and trauma), of heterozygoty, of combination of factors and 

 of complications of segregation. The different behaviour of heredity 

 of the same indices is thus in favour of segregation. 



The results of this investigation are less a final conclusion than 

 a guide for furthej' investigations by which this material will be 

 augmented and completed. 



