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 primigenzus 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. | 
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 Schoetensack 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. (Schoetensack, Der Unterkiefer des Homo heidelbergensis, Leipzig, 
1908.) G. 8.] 
D. 9 
