ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
251 
bouillon is smeared over an agar plate, and afterwards examined for 
the bacteria which may have grown up. 
Typhoid bacteria also decolorise the bouillon, but more slowly,. 
3-4-5 days. 
Influence of Variations in Composition of Gelatin on Development 
of Water Bacteria.* — Messrs. Sedgwick and Preston found that the same 
water when examined at different laboratories gave no constant results. 
Even in the same laboratory the results were different when the com- 
position of the nutrient gelatin was different. For the purpose of ascer- 
taining the cause of these varjung results, the authors have examined 
into the constituents of the ordinary gelatin and the importance thereof 
for the growth of different water bacteria. Accordingly, the importance 
of the amount of acid, of pepton, of meat, of gelatin, and of salt for for- 
warding the growth of water bacteria was tested. It was found that 
0*2 of 1/20 normal acid per ccm. of nutrient gelatin gave the best 
results, but the amount of acid was found to be dependent on the pepton 
used. Increase in the amount of j>epton aided the development of the 
water bacteria ; on gelatin which contained 15-20 grm. pepton per litre, 
far more colonies appeared than upon the ordinary gelatin, which con- 
tained only 5 grm. If, however, salt was in excess, the growth of the 
bacteria was hindered ; and if it were omitted far more colonies ap- 
peared. The meat used was not found to exert any special influence. 
The gelatin which gave the best results was that known as hide-gelatin ; 
bone-gelatin and ordinary gelatin promoted the growth of water bacteria 
in mass. 
Demonstrating Y/ild Yeasts in Trade Yeasts and New Beer.f — Herr 
H. Will has tested Hansen’s method of examining for wild yeasts by 
cultivating in 10 per cent, saccharose, with addition of 4 per cent, tartaric 
acid. He found that the results were in accord with those of the older 
procedure, and that the time was shortened by the addition of tartaric 
acid. This method also facilitates the recognition of SaccJiaromyces 
apiculatusy which could be demonstrated in 57 per cent, of trade yeasts 
and new beers. In the sugar solution it developed with the typical 
lemon-shaped cells, which permits its easy recognition, though, if it do 
not show this characteristic shape, it may be overlooked. 
Cultivation Medium for Nitrite Ferment.} — Dr. M. W. Beyerinck 
has successfully cultivated the nitrite ferment of the ammonia salts on 
agar plates by preparing this medium in the following manner : — A not 
too thick layer of agar, previously filtered after having been dissolved 
in distilled water, is allowed to set in an Erlenmeyer’s flask. The 
surface is then covered with distilled water and the medium left to 
itself. The soluble organic substances diffuse out into the water, and 
bacteria spontaneously develope therein. After a few days the water is 
poured off' and renewed. This is repeated several times. In a week to 
14 days, according to the thickness of the layer, the soluble organic 
* American Public Health Assoc., x. (1895) p. 450. See Centralbl. f. Bakteriol. 
u. Parasitenk., l te Abt., xix. (1896) p. 222. 
t Zeitschr. f. gesammte Brauwesen, xvi. pp. 29-30. See Bot. Centralbl., lxiv. 
(1895) pp. 269-70. 
X Centralbl. f. Bakteriol. u. Parasitenk., l ,e Abt., xix. (1896) p. 258. 
