made a commerce of so-called "buffalo-rugs." These "hunters" miscalled
the unhappy bison, which is not a buffalo, nor at all like that
creature, just as they gave the name "elk" to the great red deer (the
wapiti), although there was a real elk, the so-called "moose," staring
them in the face. The sudden extinction of the bison resulted partly
from the slaughter and partly from the breaking up of the herds and
the interference with their free migration by the trans-continental
railway. An interesting discovery made only this year, in regard to
the closely allied European bison, suggests that disease may also have
played a part in the destruction of the North American bison. A few
hundred individuals of the European bison are all that remain at this
day. Some are carefully preserved by the Emperor of Russia in a tract
of suitable country in Lithuania and another herd exists in the
Caucasus. Some of the Lithuanian bison have lately been dying in an
unaccountable way, and on investigating a dead individual a Russian
observer has discovered a "trypanosome" parasite in the blood. The
trypanosomes are microscopic corkscrew-like creatures, of which many
kinds have become known within the last ten or fifteen years. They are
"single cells"--that is to say, "protoplasmic" animalcules of the
simplest structure--provided with a vibrating crest and tail by means
of which they swim with incessant screw-like movement through the
blood. They rarely exceed one thousandth of an inch in length
exclusive of the tail. The poisons which they produce by their life in
the blood are the cause of the sleeping-sickness of man (in tropical
Africa), of the horse and cattle disease carried by the tsetze fly,
and of many similar deadly diseases--a separate "species" being
discovered in each disease. A peculiar species is found in the blood
of the common frog, and another in that of the sewer-rat. The last
discovery of a "trypanosome" is that of one in the blood of the
African elephant, announced to the Royal Society by Sir David Bruce.

It is a matter of great interest that a trypanosome has been found in
a death-stricken herd of European bison. It suggests that one of the
causes of the disappearance of the bison, both in Europe and America,
may be the infection of their blood by trypanosomes, and that
possibly, whilst a freely migrating and vigorous herd would not be
extensively infected, a dwindled and confined herd may be more liable
to infection