YELLO W FE VER. 401

tinal cavity. In the latter it is never found. The isola-
tion of the specific microbe was only possible in 58 per
cent, of the cases, and in some rare instances may be ac-
complished during life.

The bacillus, at first sight, presents nothing morpho-
logically characteristic. It is a small bacillus with
rounded ends, generally united in pairs in the culture
and in small groups in the tissues. It is 2-4 /JL in length,
and, as a rule, two or three times longer than broad (Fig.
in). It is pleomorphous, and has flagella. By em-
ploying suitable methods it can be found in the organs

FlG. in.—Bacillus icteroides (Sanarelli).

of yellow fever cadavers, usually united in little groups,
always situated in the small capillaries of the liver, kid-
ney, etc. The best method of demonstration is to keep
a fragment of liver, obtained from a body soon after
death, in the incubator at 37° C. for twelve hours and
allow the bacteria to multiply in the fresh tissue before
examination. •

The bacillus can be cultivated upon the ordinary
media. Upon gelatin plates it forms rounded, transpar-
ent, granular colonies, which during the first three or
four days present somewhat the appearance of leukocytes.

26