982 
been found only in small numbers and in a 
limited number of cases.” 
Sternberg has recently called attention * 
to the close similarity between his descrip- 
tion of the ‘ Bacillus X’ mentioned in the 
above quotation and the description of ‘ B. 
icteroides’ given by Sanarelli, and makes 
out a strong case for the view that the two 
are identical. 
Sanarelli began his work in February, 
1896, shortly after his appointment as Di- 
rector of the Institute of Experimental Hy- 
giene at the University of Montevideo. In 
7 out of 12 autopsies made by him upon 
the bodies of victims of yellow fever there 
was found a specific bacillus (B. icteroides) 
which he regarded as hitherto undescribed. 
The reasons assigned for the failure of him- 
self and others to isolate this microbe in all 
cases of yellow fever are: 1. That B. icter- 
oides multiplies in the human body only to 
a limited extent, the complete and charac- 
teristic effects of the disease being produced 
by only a very small quantity of toxin. 2. 
That this toxin, whether directly or indi- 
rectly, facilitates to a remarkable degree 
secondary infection of all kinds. These 
secondary infections with the colon bacillus, 
streptococcus, staphylococcus, etc., may of 
themselves be fatal to the patient, and San- 
arelli believes that the fatal termination or 
several cases observed by him is to be ex- 
plained in this way. 38. That these mixed 
infections not only lead to the speedy dis- 
appearance of the specific microbe, but also 
frequently end by transforming the organ- 
ism of the patient into a culture medium 
for almost all kinds of intestinal bacteria. 
The bacteriological complications arising 
from these facts enhance considerably the 
technical difficulties of isolating the specific 
bacillus. Sanarelli did not succeed in find- 
ing the germ in the gastro-intestinal con- 
tents and is inclined to doubt if it usually 
occurs there at all; he did, however, dis- 
* Centralbl. f. Bakt. I. Abth. XXII., Nos. 6and 7. 
SCLENCE. 
[N.S. Von. VI. No. 157. 
cover it in the circulating blood and in 
some of the important organs of the body,. 
notably in the liver. He refers to the pre- 
vailing belief that the infectious material 
in yellow fever is localized in the stomach 
and is to be sought for especially in the 
black vomit, but prefers, for his part, to re- 
gard the gastric disturbances as due to the 
selective action of the toxin, a view similar, 
it will be remembered, to his interpretation 
of the intestinal lesions of typhoid fever. 
Bacillus icteroides grows readily upon the 
ordinary-nutritive media, fluid and solid. 
It is described as a rod about 24-4» in 
length, with rounded ends, often joined in 
pairs, and staining readily with the ordi- 
nary aniline dyes, but decolorized by Gram’s. 
method. The colonies upon a gelatin plate 
resemble in some particulars those of the 
colon bacillus, but never show any trace 
of the chestnut color developed in cultures 
of the latter ; so-called pleomorphism of the: 
colonies is, however, marked. 
Contrary to what is true of most of the 
known pathogenic microbes, the growth of 
B. icteroides upon agar is especially charac- 
teristic and furnishes a diagnostic test of 
the first importance. If the cultures are 
allowed to develop in the incubator at 37° 
for from 12 to 24 hours, and are then trans- 
ferred to a temperature of from 20° to 28°, 
there is produced what Sanarelli regards as. 
a highly characteristic appearance. The 
growth at the lower temperature forms a 
sort of halo around the portion of the colony 
developed in the incubator, and this appear- 
ance is so singular that according to Sana- 
relli a mere superficial inspection suffices to 
distinguish immediately, and with the naked 
eye, a colony of B. icteroides in the midst of 
all other bacterial colonies yet described. 
As the growth goes on, an effect is pro- 
duced as if a layer of opaque paraffin had 
been poured over the agar and then impres- 
sions made in it with a small circular seal, 
the imprints of this seal corresponding with. 
