116 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
products, but is an expression of the vitality of the living milk, and is 
instantly extinguished when milk is heated to 100° C. Exposure to the 
action of steam for 3 hours or more does not affect the germicidal power 
of milk, and this is to be ascribed to the increased acidity resulting from 
the action of steam. But an exposure to steam for less than 1J hours 
renders milk a good cultivation medium. In a few days’ time a reversal 
ensues, and this is probably the result of the growth of the bacilli, the 
formation of acid, and the coagulation of the casein. Yet even in acid 
and clotted milk viable cholera bacilli will be found at the expiration of 
a week. The practical outcome of these observations is that raw cow’s 
milk is less suspicious than boiled as regards cholera bacilli. 
Effect of Bile, Urea, and Borax on Cholera Bacilli.* — Herren H. 
Leo and R. Sondermann have studied the effect of bile, urea, and borax 
on the growth of cholera bacilli. Fresh ox-gall was discontinuously 
sterilized by heating it for several days to 60° C. The urea and borax 
were dissolved in water and then steam sterilized. When the medium 
(gelatin) contained 50 per cent, of bile, its influence was favourable to 
the growth of the comma bacilli ; if considerably more it became un- 
favourable but never fatal. This promotion of growth was probably due 
to the increased alkalinity imparted to the medium through the bile, 
though increased fluidity probably had some influence, as experiments 
made by adding water showed. These two factors, increased alkalinity 
and fluidity, overcame the inhibitory effect of the bile acids. Hence in 
the organism the bile can have no inhibitory effect, as the intestine 
rarely contains 50 per cent. The addition of 1*45 per cent, of urea had 
an evidently restraining effect, and this increased with increase of the 
amount of urea, though more than 4*5 per cent, could not be added 
without affecting the solidification of the gelatin. A 10 per cent, 
solution of urea was found to kill cholera bacilli in 20 hours. 
With regard to borax it was found that 1 : 1000 exerted an inhibitory 
action, but none was observable when the proportions were 1 : 500ft. A 
half per cent, borax solution possessed bactericidal powers, while a 
5 per cent, solution killed cholera bacilli in 17 hours. 
Hew Diagnostic Criterion of the Bacillus of Typhoid Fever.f — 
Though Bacillus typhosus and Bacterium coli commune may usually be 
distinguished by their behaviour in sterile milk, in saccharated media,, 
and in pepton water, a further criterion is sometimes desirable. This, 
says Sig. C. Gorini, may be found by adding 2 per cent, of urea to a 
gelatin cultivation of typhoid. On the first two days the organism grows 
in the usual way, but on the third or fourth the gelatin, which was 
rendered cloudy by the urea, clears up, and fine white granules, appa- 
rently crystals of carbonate of ammonium, which are disseminated 
throughout very regularly, appear in the medium. Bacterium coli also 
forms crystals, but these only accumulate in little heaps along the inocu- 
lation track. Besides this numerous gas-bubbles can be seen, and these 
are apparently due to the splitting up of the urea into carbonic acid and 
ammonia. 
* Zeitschr. f. Hygiene, xvi. p. 505. See Centralbl. f. Bakteriol. u. Parasitenk., 
xvi. (1894) pp. 198-9. 
t Giornale d. Reale Soc. Ital. d’ Igiene, 1894, No. 7. See Centralbl. f. Bakteriol. 
u. Parasitenk., xvi. (1894) p. 713. 
