mp Lazear" upon four individuals, who freely
consented to it; and in three of the four a typical attack of yellow
fever resulted from the blood injection. The blood was taken from a vein
at the bend of the elbow on the first or second day of sickness and was
injected subcutaneously into the four nonimmune individuals, the amount
being in one positive case 2 cc, in one 1.5 cc, and in one O.5 cc. In
the case attended with a negative result, a Spanish immigrant, a
mosquito inoculation also proved to be without effect, and Dr. Reed
supposes that this individual "probably possesses a natural immunity to
yellow fever." Dr. Reed says with reference to these experiments:

It is important to note that in the three cases in which the injection
of the blood brought about an attack of yellow fever, careful culture
from the same blood, taken immediately after injection, failed to show
the presence of Sanarelli's bacillus.

Having demonstrated the fact that yellow fever is propagated by
mosquitoes, Dr. Reed and his associates have endeavored to ascertain
whether it may also be propagated, as has been commonly supposed, by
clothing, bedding, and other articles which have been in use by those
sick with this disease. With reference to the experiments made for the
solution of this question I cannot do better than to quote _in extensa_
from Dr. Reed's paper read at the Pan-American Medical Congress in
Havana.

[This extract from Dr. Reed's paper describes in careful scientific
detail the experiments which finally established the fact that the
contagion came through mosquitoes, and in no other way. Into a small
house, thoroughly air-proof, were brought bedclothes, clothing, and
other articles which had been contaminated by yellow fever patients.
Then for twenty days men who were nonimmune to the fever slept in this
building, with no evil effects. This experiment was repeated several
times. Then in another building similar, except that it was ventilated
by mosquito-proof windows, and had been thoroughly disinfected, another
volunteer was bitten by mosquitoes which had first bitten patients
suffering with yellow fever; and he developed the disease. The last
paragraph of the extract is as follows:]

"Thus at Camp Lazear, of seven nonimmunes whom we attempted to
infect by means of the bites of contaminated mosquitoes, we have
succeeded in conveying the disease to six, or 85.71 per cent. On the
other hand, of seven nonimmune