414 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
(4) Chemical Changes (including Respiration and Fermentation). 
Action of Diastase on Reserve-Cellulose in Germination.* — Dr. J. 
Griiss describes this process in further detail, the species specially- 
studied being the date-palm. During germination the diastatic enzyme 
passes from the cell-cavity into the thickened cell-wall, especially in 
the neighbourhood of the scutellum. This is followed by a partial 
hydrolytic solution, by which the galactan is removed from the cell- 
wall. In this manner the hyaline marginal zone is formed. The 
mannan which remains in this zone undergoes alloolysis ; the mass 
which is permeated by the enzyme passes over into the various mannin 
stages, and finally into mannose. According to the reactions a leuco- 
mannin and a cyanomannin can be distinguished. 
Alcoholic Fermentation without Yeast-Cells.f — Herr E. Buchner 
finds that the aqueous extract loses its fermentative properties when 
kept for two days at 0°, or for one day at the ordinary temperature. 
This deterioration, which is accompanied by a loss in coagulable albumen, 
is attributed to the presence of peptonic enzymes. The extract retains 
its activity much longer in the presence of strong solutions of cane- 
sugar. When the extract is mixed with its own volume of a 50 per cent, 
solution of cane-sugar, fermentation continues for 7 days at moderate 
temperature, and for 14 days at 0°. That the activity is not due to the 
presence of plasma particles in the extract, is proved by the fact that 
the activity of the solution is not destroyed by antiseptics, such as 
chloroform, benzene, sodium arsenite, &c. The extract may also be 
evaporated to dryness at 30°-35° under reduced pressure ; and an aqueous 
solution of the residue is also capable of fermenting cane-sugar. The 
dried extract may be kept for at least 20 days without losing its active 
properties. Only on one occasion was it found possible to precipitate 
the active substance, zymase, by the aid of alcohol. Well warmed yeast 
was dried at 37°; one portion was mixed with water and heated to 100°; 
plate cultures proved that all the cells had been destroyed, and yet the 
solution was capable of fermenting a sterilised cane-sugar solution. 
The second portion was heated to 140°-145° for one hour ; it was 
found to be incapable of bringing about fermentation, owing to the de- 
struction of the zymase. 
Reduction of Nitrates.* — M. P. P. Deherain made a number of 
experiments in which solutions ofjfpotassium nitrate were inoculated with 
straw, fresh manure, horse-dung, and peat manure. Nitrate-reducing 
organisms were found in straw and fresh manure, but not in peat manure. 
Horse-dung contained sufficient to reduce nitrates at 30°, but there was 
very slight reduction at the ordinary temperature. The denitrifying 
organisms develop rapidly in solutions containing starch and potassium 
nitrate, but not at all in pure nitrate solutions. The organisms will 
live in starch alone ; but in absence of nitrate the starch is only very 
slowly destroyed. Solutions exhibiting the most rapid reduction contain 
starch (0*25), potassium nitrate (0*2), and potassium phosphate (0*01 
* Bot. Central bl lxx. (1897) pp. 242-61 (2 pis.). Cf. this Journal, 1895, p. 200. 
t Ber. Deutsch. Chem. Gesell., xxx. (1897) pp. 1110-3. See Journ. Chem. Soc.,. 
lxxi. and lxxii. (1897) pp. 380-1. Cf. this Journal, ante , p. 222. 
X Ann. Agronom., xxifi. (1897) pp. 49-79. See Journ. Chem. Soc., lxxi. and 
lxxii. (1897) pp. 381-2. 
