802 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
towards the posterior pole, which is caused by a strong galvanic current, 
is the result of chemical processes which take place at that pole. 
Curvature towards the negative pole resembles heliotropic and geotropic 
curvatures in the fact that it takes place when the galvanic current acts 
only upon the apex of the root. This may or may not be a purely 
chemical irritation dependent on the formation of hydrogen peroxide. 
(4) Chemical Chang-es (including Respiration and Fermentation). 
Digestion of Albuminoids by the leaves of Pinguicula. * — From 
a series of observations on Pinguicula vulgaris^ Herr N. Tischutkin has 
come to the conclusion that the digestive processes effected by the 
mucilaginous secretion from the glands on the leaves is not due to any 
fermentative substance contained in the fluid itself, but to the action of 
the bacteria which always accompany the putrefaction of the organic 
substance. The experiments were made both with dead flies and with 
small pieces of boiled white of egg. 
Action of Carbonic Acid on the products of Fermentation.f — 
M. Luidet’s memoir on the influence of carbonic acid on the fermentative 
process discusses the question whether alcohol exerts an inhibitive 
influence on the vegetation of yeast. We may take as an example of his 
meaning the question, when wort contains 13-15 per cent, of alcohol, 
does therefore fermentation cease? Against this the author asks 
whether the chief product of saccharine fermentation, carbonic acid, 
does not rather, after a certain point has been reached, exert a similar 
inhibitive influence on the yeast. He endeavours to answer the question 
in the following way : — In four equal sized flasks he fermented equal 
quantities of wort with like amounts of yeast, and so arranged it that 
the carbonic acid pressure should be different in each flask ; the pres- 
sure of CO 2 in the first flask being equal to 0 * 2 cm. of mercury, in the 
second to 20 cm., in the third to 43 cm., and in the fourth to 60 cm. 
The result showed that the carbonic acid pressure had no influence on 
the course or products of fermentation. The determination of the alcohol 
formed and the quantity of the yeast gave in all cases such identical 
results that the author concludes that carbonic acid development had no 
inhibitive influence on the vital activity of yeast. 
Ferment-action of Bacteria.^ — Drs. T. Lauder Brunton and A. 
Macfadyen have been making a series of experiments with Koch’s 
comma - spirillum, Finkler’s comma - spirillum, a putrefactive micro- 
coccus, scurf bacillus, and a bacillus isolated from milk by Lr. Klein. 
They come to the conclusion that the bacteria which liquefy gelatin do 
60 by means of a soluble enzyme. This enzyme can be isolated, and 
its peptonizing action demonstrated apart from the microbes which 
produce it. The most active enzyme is that formed in meat-broth, and 
its action is hindered by acidity and favoured by alkalinity. The 
bacteria which form a peptonizing enzyme on proteid soil can also 
* Ber. Deutsch. Bot. Gesell., vii. (1889) pp. 346-55. 
t Bull. Soc. Chem. Paris, ser. iii. tom. ii. No. 4, Cf. Centralbl. f. Bakteriol. u. 
Parasitenk., vii (1890) p. 62. 
X Proc. Boy. Soc., xlvi. (1890) pp. 542-53. 
