PROTECTIVE INOCULATIONS. 309 
“1. After the ingestion of sterilized (by heat) and subsequently carbolized 
agar cultures of cholera bacteria the serum of man acquires an immunizing 
property as regards the cholera vibrio. 
_ 2 Asa result of the ingestion of sterilized agar cultures the individual 
is protected from infection with virulent cultures of the cholera vibrio by way 
of the intestine. 
‘*3. The discharges of individuals immune against cholera, and to all out- 
ward appearance in perfect health, may contain a great number of cholera 
vibrios (in case they are in any way introduced into the intestine) and may 
thus serve to propagate the malady.” 
DIPHTHERIA. 
According to Roux and Yersin, “attenuated varieties ” of the diph- 
theria bacillus may be obtained by cultivating it at a temperature of 
39.5° to 40° C. in a current of air; and these authors suggest that a 
similar attenuation of pathogenic power may occur in the fauces of 
convalescents from the disease, and that possibly the similar non- 
pathogenic bacilli which have been described by various investigators 
have originated in this way from the true diphtheria bacillus. These 
authors further state, in favor of this view, that from diphtheritic 
false membrane, preserved by them in a desiccated condition for five 
months, they obtained numerous colonies of the bacillus in question, 
but that the cultures. were destitute of pathogenic virulence. They 
say: 
‘Tt is then possible, by commencing with a virulent bacillus of diphtheria, 
to obtain artificially a bacillus without virulence, quite similar to the attenu- 
ated bacilli which may be obtained from a benign diphtheritic angina, or even 
from the mouth of certain persons in good health. This microbe, obtained 
artificially, resembles completely the pseudo-diphther:tic bacillus ; like it, it 
grows more abundantly at a low temperature ; it renders bouillon more rap- 
idly alkaline ; it grows with difficulty in the absence of oxygen.” 
Subcutaneous inoculations in guinea-pigs of a small quantity of a 
pure culture of the bacillus (0.1 to 0.5 cubic centimetre of a bouillon 
culture) cause death in from one to four or five days. The usual 
changes observed at the autopsy are— 
‘* An extensive local cedema, with more or less hyperzemia and ecchymo- 
sis at the site of inoculation, frequently swollen and reddened lymphatic 
glands, increased serous fluid in the peritoneum, pleura, and pericardium, 
enlarged and hemorrhagic suprarenal capsules, occasionally slightly swollen 
spleen, sometimes fatty degenerations in the liver, kidney, and myocardium. 
We have always found the Léffler bacilli at the seat of moculation most 
abundant in a grayish-white, fibrino-purulent exudate present at the point of 
inoculation, and becoming fewer at a distance from this, so that the more re- 
mote parts of the cedematous fluid do not contain any bacilli” (Welch and 
Abbott). 
The authors quoted agree with Loffler and others in stating that 
the bacillus is found only at the point of inoculation. In all cases 
