BACILLUS TYPHOSUS. 419 
quantitative only, and not qualitative, so far as the 
cholera spirillum and typhoid bacillus, at least, are 
concerned. They conclude, nevertheless, that these 
investigations will render valuable assistance in the 
clinical diagnosis of cholera and typhoid fever. It 
developed through further research that before the 
development of the bactericidal substances agglutina- 
tive substances usually appeared in the blood. 
Wipau Test. The first practical application of the 
use of serum, however, for the early diagnosis of 
typhoid fever on a more extensive scale was made by 
Widal, and reported with great fulness and detail in a 
communication published in June, 1896. Widal con- 
firmed the reaction as above described, proved that the 
agglutinative reaction was one of infection and usually 
occurred early, elaborated the test, and proposed a 
method by which it may be practically applied for 
diagnostic purposes. Since then the serum test for 
the diagnosis of typhoid fever has come into general 
use in bacteriological laboratories in all parts of the 
world, and though the extravagant expectations raised 
at the time when Widal first announced his method of 
applying this test have not been entirely fulfilled, it 
has, nevertheless, proved to be of great assistance in 
the diagnosis of obscure cases of the disease, and it is 
now one of the recognized tests for the differentiation 
of the typhoid bacillus. 
It should also be mentioned that to Wyatt Johnson, 
of Montreal, belongs the credit of having brought this 
test more conspicuously before the public by intro- 
ducing its use into municipal laboratories, suggesting 
that dried blood should be employed in place of blood- 
serum (Widal having previously noticed that drying 
