376 ON THE CO-EXISTENCE OF MAN 
that thus a doubt might exist as to its assumed antiquity. After 
hearing this remark, I exposed a minute fragment to the flame of a 
candle, when it gave out the odour of burnt animal matter; and on 
immersing another fragment in hydrochloric acid, after effervescence, 
a soft gelatinous substance, nearly the size of the original fragment, 
was left. Knowing full well that M. Delesse and M. Lartet would 
cordially agree on the importance of the most scrupulous investiga- 
tion of every fact produced in evidence on this recently-agitated 
question of the antiquity of Man, I communicated to both of them 
what I have stated above respecting this bone. I received immedi- 
ately answers from them; and these, with their leave, I now give, 
not only because of their confirmation of the opinions they formerly 
expressed, but as containing some additional remarks of much 
interest. 
M. Delesse, in his letter dated the 19th instant, says :— 
“The specimen of the rib which I gave you was incontestibly 
found in a sand-pit (sabloniére), where it was associated with the 
bones of animals no longer existing in the country—as, for example, 
the Beaver. J would observe that the presence of gelatine can in 
no way be opposed to the antiquity of that rib. I have only just 
now brought to a conclusion a long series of researches by which I 
have shown that bones even of a high antiquity still retain a notable 
proportion of organic matter. If you take the bones of an Ichthyo- 
saurus from the Lias, or of reptiles from the Muschelkalk, you will 
easily satisfy yourself that,in spite of their great antiquity, they still 
contain a very notable proportion of organic matter. Coprolites from 
the oldest formation contain it. On the other hand bones compa- 
ratively recent, such, for instance, as those found in caverns or in 
travelled materials, have no great amount of organic matter. In 
brief, the preservation of organic matter in bones is very irregular; 
it depends on the nature of the rock in which they are found, at 
least quite as much as on their antiquity. 
«‘T pronounce no opinion as to the nature of the instrument that 
had been employed in sawing that rib, for I made no experiments on 
the subject ; but M. Lartet, whose caution and sagacity are known to 
you, made a special examination of the question along with eminent 
physiologists; and they had no doubt that the rib had been cut by a 
sharp flint.”’ 
M. Lartet, in his letter dated the 22nd instant, states as follows: — 
