THE MOST ANCIENT REMAINS OF MAN 
Later during the same summer the specimens were 
shown also to Professor McGregor, of Columbia University. 
Since then they have been demonstrated on a number of 
occasions, including that of the Twenty-first International 
Congress of Americanists at the Hague, 1924. 
Finally, during this same year (1924), there appeared 
in the Proceedings of the Academy of Sciences, Amsterdam, 
three new important publications on the Pithecanthropus 
remains by Professor Dubois: The first, on the skull and 
brain, with which the author now definitely associates the 
fossil mandible, all three teeth, and the thigh bone; the 
second showing eleven excellent plates of the specimens; 
and the third dealing with the femur; with a final exhaus- 
tive work on the whole of the remains promised for a not- 
far-distant future. 
In these latest and ripest communications on the Java 
remains are found the following statements of special 
interest: 
The bones are in a state of perfect mineralization. Their specific 
gravity, like that of the bones of other mammals dug up at Trinil, has 
risen to about 2.7. They contain only traces of organic matter in the 
form of human substances, which give them a chocolate-brown color. 
The skull-cap has been greatly corroded on the outer surface by 
sulphuric acid, formed from pyrites in the volcanic tufa; the femur 
appears to be free of such corrosions. 
The physical and chemical characters of the bones are 
such, in Dubois’s opinion, that they “‘stamp the remains of 
Pithecanthropus as Pliocene’’; which possibility is further 
strengthened by the somatological characteristics of the 
specimens. Dubois, therefore, is still inclined to regard 
the Pithecanthropus remains as late Pliocene rather than 
Pleistocene. 
Ventrally, the skullcap, particularly in the frontal 
region, shows strong impressions of the cerebral convolu- 
tions. In details of its conformation it agrees partly 
with man, partly with the gibbon. ‘“‘The form of the 
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