114 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
suitable for the filtration of waters which have not undergone sufficient 
natural filtration, and that it does not deliver a germ-free water. 
Testing the Pasteur-Chamberland Filter * — Drs. T. Smith and 
Y. A. Moore show how, by a very simple contrivance, it can be demon- 
strated that the pores in the porcelain bougie are bigger than most 
bacteria. A bougie of the usual shape is put inside a long, pretty 
narrow test-tube, and the latter plugged at the top with cotton-wool. 
The combination is then dry- sterilized. 
To show how the bacteria pass through, a flask of bouillon is inoculated 
with a pure cultivation of a species of bacterium, and having been incu- 
bated for some hours, is run into the filter by means of a sterilized 
pipette. The flask is then connected with an air-pump, and some of the 
fluid drawn through the filter until the latter is surrounded up to a 
certain height with a layer of fluid. The whole apparatus is then 
incubated. In a few days the bouillon becomes turbid. 
The experiment may be reversed ; that is, the fluid may be sucked 
up into the filter from without, but the details of the process are more 
complicated, and much less satisfactory. 
Method for Differentiating between Bacilli of Typhoid Fever and 
Water Bacteria closely resembling them.j — Dr. J. Weyland examined 
some drinking water suspected of giving rise to enteric fever, and 
isolated therefrom a species of bacterium the morphological and cultiva- 
tion characteristics of which were not to be certainly distinguished from 
those of true typhoid bacilli. The negative indol reaction served to 
increase the suspicion of their identity. 
The author first set about comparing the vitality of these bacilli 
with those of real typhoid, but no notable differences were shown, and 
recourse was had to chemistry. As the bouillon cultivation of both 
kinds had an acid reaction, the amount of acid formed in 10 ccm. of milk 
serum was first ascertained. For this Petruschsky’s method was adopted, 
but phenolphtalein was substituted for litmus as indicator. After 
having been incubated for three days, it was found that the serum 
inoculated with the real typhoid required 8-9*1 ccm. of 1/100 alkali 
solution to neutralize it, while the pseudo-typhoid took 12 *9-15 *4 ccm. 
The amount of carbonic acid formed by the two kinds of bacteria was 
then determined by Pettenkofer’s method ; this consists in forcing the 
carbonic acid formed by the bacteria into tubes filled with baryta water, 
and estimating the diminution of alkalinity by titration with oxalic 
acid. 
The only caution to be observed is that the fermentation bulbs must 
be kept at similar temperatures, as the slightest difference in heat has an 
important influence on the production of carbonic acid. This part of 
the experiment lasted 10 days, and the result of it was that the pseudo- 
typhoid bacilli were found to have produced about five times as much 
carbonic acid as the true typhoid bacilli. A repetition of the experiment 
gave a similar result. It was accordingly determined that the water 
bacteria in question were not typhoid bacilli. 
* Centralbl. f. Bakteriol. u. Parasitenk., pp. 628-9 (1 fig.), 
f Archiv f. Hygiene, xiv. p. 374. See Centralbl. f. Bakteriol. u. Parasitenk., 
xii. (1892) pp. 338-9. 
