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THE AMERICAN NATURALIST [Vol. XLVI 



opinions of Boas, Elliot Smith and Hrdlicka have been 

 sought. Boas is one of the most positive as to the hered- 

 itary stabilitv of head form. He observes (1911, pp. 

 7-9): 



Among European peoples head proportions are considered among 



of " dolichocephalic " and brachycephalie " individuals the children 



dolichocephalic or brachycephalie head form. Head form thus con- 

 stitutes a case of almost typical alternating heredity (p. 55). No evi- 

 dence has been obtained, however, to show that either brachycephaly 

 or dolichocephaly is dominant. Children exhibit one head form or the 

 other, and the cephalic index or ratio of breadth to length undergoes 

 only slighl alteration during growth, or ontogeny. 



Elliot Smith (letter of August 12, 1911) is "firmly 

 convinced that the form of cranium, orbits, nose, jaws, 

 limb bones, etc., in the 'Armenoid' and * Proto-Egyptian ' 

 series are very stable or even fixed 'unit characters' 

 which do not really blend, but that certain elements of 

 mosaic assemblage of characters may be grafted on to 

 others belonging to the other race." 



Opinions as to Blending. — It will be noted that Boas 

 (1895) admits a certain blending of head form in crosses. 

 Hrdlicka (letter, November 1, 1911) speaks even more 

 guardedly as to the hereditary stability of head form. 

 He says: 



As to the head form constituting a " unit character" which does not 

 blend in intermixture, I am not able to give a conclusive opinion, but 

 my experience and other considerations lead me to be very skeptical 

 that such is the case to any great extent. The subject is a very com- 

 plex one and requires considerable direct investigation in different lo- 

 calities and with different peoples before the exact truth can be known. 

 ... As to the statement that long or broad head form is a stable or 

 unit character not blending in intermixture, I think that only the first 

 part of the proposition may be held as fairly settled. But even then I 

 should change the word "stable" to "persistent," and qualify the 

 phrase by adding "under no greatly differing and lasting environ- 

 mental conditions." 



That prolonged interbreeding or intermixture tends 

 to break down the stability of hereditary head form is 



