612 BACTERIOLOGY. 
its use will be absolutely negative in cases in which an 
amount of toxin has been produced sufficient to destroy 
life. He, therefore, insists upon the early use of the 
serum, and thus the destruction of the organism before 
it has elaborated the fatal proportion of its toxin. It 
is claimed that in thirty-one cases treated with the serum 
the mortality was only 32 per cent., whereas in South 
America, where the treatment was applied, the mortality 
of yellow fever often rises to 50 per cent. (Sanarelli). 
Since Sanarelli’s supposed discovery a number of 
investigations have been made into the causal relation of 
this organism to the disease, some of which seem to 
cast considerable doubt upon its being the specific 
cause of yellow fever, while others are in its favor. 
Novy, ina recent paper (September, 1898), comes to 
the conclusion, after an exhaustive examination into 
this subject, that the Sanarelli bacillus belongs to the 
typhoid group, and that it is not the cause of yellow 
fever, which is yet to be worked out. 
Novy’s chief objection to this bacillus rests upon 
the fact that yellow fever is stopped by a frost and that 
this bacillus is not injured by much greater cold. It is 
perfectly possible, however, that the infection is carried 
in some indirect way, as by insects, and that the 
carriers of infection are affected by the cold, and so the 
dissemination of the poison is prevented. The long 
immunity conferred by an attack and the peculiar effect 
of cold on the spread of the disease are nevertheless 
difficult to explain by means of the known character- 
istics of this bacillus. In September a report by 
Geddings and Wasdin appeared which favored the 
claims of Sanarelli, they finding the bacilli in almost 
every case of yellow fever, and not in any which were 
