X, B, 2 Schobl: Diagnosis of Asiatic Cholera 148 
spreading, colonies. Although the inhibition of growth by Dieu- 
donné’s medium is evident in some cases, they do not grow on 
alkaline ox-blood agar (Tables II, VII, XI, XIJ, XIII). Bacteria 
of this class do not acidify lactose and are evidently dangerous 
competitors of the cholera vibrio during the enrichment process 
(Table II). 
The number of examinations in which peptone solution of 
+1, +0.5, —0.5, and —1 reaction was used being about the same, 
the results allow a fair comparison. When +1 peptone was 
used, the cholera vibrio was recovered in 11 per cent; from 
peptone +0.5, reaction in 61 per cent; from —0.5 peptone solu- 
tion, in 88.2 per cent; and peptone of —1 reaction gave 94.2 
per cent positive results. 
As to the bile medium the results were very unsatisfactory. 
It failed three times out of five. In our experiments the bile 
medium was prepared according to Ottolenghi’s prescription, 
with the exception that dry bile was used instead of fresh, the 
latter not being available. Whether the low percentage of pos- 
itive results was due to that fact or not I am not in a position 
to say. In this connection it may be of interest to mention 
that of the 20 strains of vibrios planted in human bile 2 strains © 
of true cholera and 1 choleralike vibrio refused to grow in 
the bile. 
Much better results were obtained with Kraus’s medium. 
It was noticed that this medium eliminated the bacteria of the 
coli group more thoroughly than peptone solution, but the bac- 
teria which prefer alkaline reaction thrive in it. Owing to the 
fact that the surface of the medium is of the least degree of 
alkalinity, they frequently form a pellicle, thus subduing the 
growth of the cholera vibrio. As the degree of alkaline re- 
action decreases with the age of the medium, more concen- 
trated solutions of alkaline ox blood in meat broth are necessary 
in order to achieve the same selective effect. 
All considered, Kraus’s medium has a decided advantage 
over the peptone solution. The use of this medium will be 
particularly indicated in searching for carriers. In a laboratory 
like that of the Bureau of Science, where daily examinations 
of stools for cholera are being conducted all the year round, 
it is necessary that a sufficient amount of ox blood always be 
kept on hand, as Dieudonné’s plates are indispensable in our 
work. This being the case, Kraus’s medium can be easily 
prepared. 
Combinations of peptone solution and selective enriching me- 
dium suggest themselves. The fact that the peptone solution 
