Post-Darwinian Discoveries 129 



acquainted with the surprising shape of the eye-orbit, of the nose, 

 and of the whole upper part of the face. Isolated lower jaws found 

 at La Naulette in Belgium, and at Malarnaud in France, increase 

 our material which is now as abundant as could be desired. The 

 most recent discovery of all is that of a skull dug up in August of 

 this year [1908] by Klaatsch and Hauser in the lower grotto of the 

 Le Moustier in Southern France, but this skull has not yet been fully 

 described. Thus Homo primigenius must also be regarded as 

 occupying a position in the gap existing between the highest apes 

 and the lowest human races, Pithecanthropus, standing in the lower 

 part of it, and Homo primigenius in the higher, near man. In order 

 to prevent misunderstanding, I should like here to emphasise that in 

 arranging this structural series anthropoid apes, Pithecanthropus, 

 Homo primigenius, Homo sapiens I have no intention of estab- 

 lishing it as a direct genealogical series. I shall have something to 

 say in regard to the genetic relations of these forms, one to another, 

 when discussing the different theories of descent current at the 

 present day 1 . 



In quite a different domain from that of morphological relation- 

 ship, namely in the physiological study of the blood, results have 

 recently been gained which are of the highest importance to the 

 doctrine of descent. Uhlenhuth, Nuttall, and others have established 

 the fact that the blood-serum of a rabbit which has previously had 

 human blood injected into it, forms a precipitate with human blood. 

 This biological reaction was tried with a great variety of mammalian 

 species, and it was found that those far removed from man gave no 

 precipitate under these conditions. But as in other cases among 

 mammals all nearly related forms yield an almost equally marked 

 precipitate, so the serum of a rabbit treated with human blood and 

 then added to the blood of an anthropoid ape gives almost as marked 

 a precipitate as in human blood ; the reaction to the blood of the 

 lower Eastern monkeys is weaker, that to the Western monkeys 

 weaker still ; indeed in this last case there is only a slight clouding 

 after a considerable time and no actual precipitate. The blood 

 of the Lemuridae (Nuttall) gives no reaction or an extremely weak 

 one, that of the other mammals none whatever. We have in this not 

 only a proof of the literal blood-relationship between man and apes, 

 but the degree of relationship with the different main groups of apes 

 can be determined beyond possibility of mistake. 



1 [Since this essay was written Sehoetensack has discovered near Heidelberg and briefly 

 described an exceedingly interesting lower jaw from rocks between the Pliocene and 

 Diluvial beds. This exhibits interesting differences from the forms of lower jaw of 

 Homo primigenius. (Sehoetensack, Der Unterkiefer des Homo heidelbergensis. Leipzig, 

 1908.) G. S.] 



D. 9 



