SCIENCE LETTER FROM PARIS. 761 
pliocene, but the miocene, and even the eocene periods—a classification of the 
tertiary formation made fifty years ago by Sir Charles Lyell, and founded on 
the variable proportion of shells of species still living, mixed at the same time 
with others fossilized. As negative are not of the same value as positive proofs, 
there are geologists who see in cut flints and bones conclusive evidence of man’s 
antiquity. Now, in the first place, are these objects contemporary with the strata 
in which they have been found; secondly, is it absolute certainty that these ob. 
jects have been manipulated by a human being? It isin the fauna immediately 
following the pliocene period that the flint existence of man, it is generally ad- 
mitted, isto be found. The first traces of man in Western Europe are flints 
simply broken, not fashioned, and of a nature to serve immediate wants; he lived 
in a milieu of strange fauna, where the animals of northern, temperate and south- 
ern zones were associated. The Abbe Bourgeois has discovered an immense num- 
ber of small cut flints, and has, accordingly, placed man in the miocene period. 
Respecting this, M. de Nadaille pertinently asks, of what- use these remarkably 
small flints could be to man, cut, as they must have been, with much effort and 
great labor; they were useless either for attack or defense, and still less for an 
implement or a tool. Neither have the alleged discoveries of human bones in 
tertiary strata been confirmed when subjected to rigorous analysis. The origin of 
humanity is still shrouded in mystery ; paleontology and zoélogy, no more than 
geology, have yet found out the exact cradle of our species, nor to link it to some 
Other anterior species. There are points of union which have escaped demon- 
stration; there are veritable /acunes which render classification difficult; there are 
variations impossible to explain. These remarks do not touch what is in the man 
—the supreme form of indifference, intelligence, articulated language, perfecti- 
bility. 
Professor Fredericy, of Liege, has investigated the subject of the coagulation 
of the blood. Extracted from the organism, blood solidifies, forms a mass called 
fibrine ; the same remark applies to lymph. Before coagulation, blood consists . 
of globule and a liquid called plasma; after coagulation of globules, serum and 
fibrine. Deprived of the latter, the blood does not coagulate. If blood be 
beaten up or whisked with a piece of whalebone, in a vessel, the fibrous masses 
will adhere to the rod, while the serum, holding the globules in suspension, 
will remain liquid. This is the process employed in the slaughter houses to pre- 
vent the coagulation of pigs’ blood, so essential for making black puddings. But 
from where comes this fibrine? It cannot be attributed to the new conditions in 
which it is placed, for neither cold, air, nor rest, nor the combination of the three 
can explain the phenomena. The principle of coagulation coming, not from an 
external cause, is it to be attributed to an internal one? So long as blood is in 
contact with the coats of the vein, etc., it will not coagulate—for a long time. 
Even in dead bodies, the blood is only imperfectly coagulated. But if a foreign 
body be introduced into the vein coagulation will set in. Since the end of the 
sixteenth century it has been known that it is in the liquid part of the blood—the 
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