1901] MICROSCOPICAL JOURNAL. 183 
that all the test objects receiving the abundant inocula- 
tions of the virulent pure cultures were sterile. In other 
words, not only were cultures of the bacillus used that 
were accustomed to a saprophytic existence, but these 
cultures were placed upon sterile test objects and protect 
ed against contamination, so that they were relieved from 
that microbial symbiosis which, in the economy of nature, 
plays so important a part in the suppression of patho- 
genic micro-organisms. It is known that in organic mix- 
tures the hardier saprophytes tend to overpower the ba- 
cillus pestis. 
PLAGUE AND Foop.—Our experiments show that food 
products may harbor the infective principle of plague, 
but according to experience food products are not much 
to be feared as far as their probability of carrying the in- 
fection is concerned. This latter statement does not ap- 
ply to milk and its products, for milk is a good culture 
medium for the bacillus pestis ; and we kept it alive sev- 
enteen days in cheese and seventy-two daysin butter. On 
the surface of food products it usually died very quickly. 
It did not live twenty-four hours on orange peel. We had 
similar results with figs and raisins and a large quantity 
of Chinese food products, such as smoked and dried ducks, 
dried oysters, dried cuttle fish, dried ducks’ gizzards, 
ducks’ gizzards dried and placed in oil, smoked and dried 
pork, and duck eggs preserved in a mixture of mud and 
rice chaff, all of which were infected with the bacillus 
pestis andkeptat 37° C. Inrice wefound it alive eighteen 
days after inoculating. | 
These results correspond with all our other experiments, 
which plainly prove that the bacillus cannot live long on 
the surface of objects, when dry, at temperatures above 
30° C. In one case we kept it alive one hundred and six- 
teen days, and in another ninety-six days, in water pre- 
served at low temperatures, 17° to 19° C. Under the same 
conditions the organism lived only six days at 37° C, 
