YELLOW FEVER EXPEDITION 
499 
kidney, heart blood, and cerebrospinal fluid all remained negative. One other point, 
which may be remarked upon is the comparative freedom of bacterial growth in our 
series of autopsies, when compared to the records of Sanarelli, Agramonte, and 
others. This may be partly due to the shortness of the period which was usually 
allowed to elapse between death and autopsy, to the care in thoroughly cauterising, 
and perhaps to the use of a spirit bunsen burner instead of the ordinary spirit lamp 
for heating the platinum wire and glass tubes. The broth we used showed itself very 
favourable for the growth of various bacteria when growth did occur or when plantings 
were made from other cultures. One mode of origin of the so-called agonal and 
ante-mortem invasion of bacteria which suggested itself, was the introduction of 
material by hypodermic medication which is often resorted to during the later and 
the agonal phases of the fever. 
B. Mosquito Transference 
It is incontestible that Dr. Charles Finlay, of Habana, was the first to under- 
take direct experiments to substantiate his ideas of the part played by the mosquito in 
the transmission of yellow fever. His method was to feed mosquitoes upon yellow 
fever patients (not later than the sixth day), and then after an interval of from forty- 
eight hours to four or five days to allow them to feed upon susceptible persons ; the 
view was to produce a slight attack of the fever in order to produce immunity. At a 
delightful chat we had with the courteous doctor, on July 25, 1900, he told us many 
details concerning his experiments, which were commenced so long ago as 1881. 
Altogether, one hundred and two persons had been tried in this manner, and in seven- 
teen instances some pathogenic effect had followed the bite ; this consisted in slight 
fever appearing about the fifth, sometimes as late as the fourteenth day. In no instance 
was there a definite attack of yellow fever as the result, but Dr. Finlay thought that 
a certain immunity had been conferred since only four of these persons died of yellow 
fever, though the cases were followed out to ascertain their after history, in some cases 
for four years. Naturally it was not possible to exclude intercurrent infections by 
thus working in an endemic centre, still the mode and kind of experiment which has 
since led to more definite results was laid down. The kind of mosquito used by Dr. 
Finlay was the Stegomyia fasciatus (it was referred to in his papers as Culex mosquito), 
he selected this kind on account of its town dwelling habits.* 
* It may be noted that Dr. Reed's commission not only performed their experiments with his species, but were also indebted 
to Dr. Finlay tor the eggs of the same {Philadelphia Medical Neivs, October 27, 1900). The few cases tried with such short 
gnat incubation, as Finlay used, all turned out negative (i.e., six in number) where the gnat incubation was less than ten dajs, in 
four of which, however, the gnat had been fed on the fifth day of illness of the yellow fever patient ; i.e., near Finlay's six day 
limit. A seventh case surpassed this, as the gnat had been fed on the seventh day. These numbers may be compared with those 
of the negative experiments with longer incubations (v. infra.). There is, however, a source whence may have come the 
relatively few febrile reactions which Dr. Finlay obtained in his cases for he states (Handbuch d. prakt vied., Ebstein and Schwalbs 
art., Gelbes Fieber) 'one obtains a female mosquito from a house which is free from yellow fever infection.' In an endemic 
centre like Habana, it does not follow that an insect taken in a house of this description is necessarily uninfected ; so that it is 
possible that there were some accidental infections amongst such cases, though it may be more probable that independent acci- 
dental infection in the city should have taken place since there was no isolation ; still such difficulties w ere well insurmountable 
for a private individual, and credit should be afforded for a very astute presage of future experiment. 
