ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
211 
destroys a substance capable of becoming sugar, and produces an aceto- 
fermentation. This substance is glycogen. Errera had already clearly 
perceived the existence of this glycogen. He obtained a red-brown 
colour with iodine, but no success followed his attempts at isolating it. 
M. Laurent has been able to make a step further. By the aid of 
three imperfect methods, but which gave concordant results, he has 
calculated the glycogen formed. These three methods were: — (1) To 
change by means of an acid the glycogen into a reducing sugar, without 
altering the cell-walls. (2) To weigh a quantity of healthy yeast, to 
exhaust an equal weight by autophagy, and calculate the loss by sub- 
traction. (3) To estimate the quantity of alcohol produced by a given 
weight of yeast exhausted by autophagy, and then determine the quantity 
of saccharine matter consumed. 
The result of these researches showed that the quantity of accumu- 
lated glycogen might amount to 32 per cent, by weight dry. 
The accumulation of glycogen in yeast completes the history of 
the phenomena of autophagy, and explains the results formerly observed 
by Pasteur and Duclaux, that yeast loses weight when it is fermented 
with a relatively small quantity of sugar. 
Formation of Albuminoids in Plants containing Chlorophyll.^ — 
By experiments made on several different plants, Herr W. Chrapowicki 
has determined that the formation of albuminoids takes place in the 
chromatophores, and that they are not merely transferred there from 
other parts of the plant where they are first formed. In several 
instances he was able to establish that the formation of albuminoids can 
take place in the dark. 
Formation of Cane-sugar in Etiolated Seedlings.! — In seedlings of 
Lupinus luteus which had grown for six days in the dark, Herr E. Schulze 
finds small quantities of a substance agreeing with cane-sugar in its 
behaviour under the polarizing apparatus, and in its crystalline form. 
Starch was also found, neither substance being present in the seeds 
before germination. 
Fermentation.! — M. E. Bourquelot has grouped the various phe- 
nomena caused by the action of soluble and organized ferments, interest- 
ing alike to chemist, pharmacist, and mycologist. In the introduction 
the author gives an historical account of fermentation ; and the first 
part of the book is devoted to an account of fermentation produced by 
soluble ferments. These are classed in the following manner : — (1) The 
saccharification of starch (diastase) ; (2) the inversion of cane-sugar 
(invertin) ; (3) the doubling of glucosides (emulsin, myrosin) ; (4) the 
peptonization of albuminoids (pepsin, trypsin, and papaine) ; (5) the 
coagulation of casein {presure ) ; (6) the decomposition of urea (urease). 
The second part of the book treats of fermentation produced by 
organized ferments, the principal of which are the alcoholic and lactic 
fermentations, the ammoniacal fermentation of urea, butyric, sulphydric, 
acetic, and nitric fermentations. 
* Arb. St. Petersburg. Naturf. GeselL, xviii., pp. 1-27 (Russian). See Bot. 
Centralbl., xxxix. (1889) p. 352. f Ber. Deutscli. Bot. GeselL, vii. (1889) pp. 280-1. 
X ‘ Les Fermentations,’ Paris, 1889, 8vo, 170 pp. See Rev. Mycol., xi. (1889) 
p. 209. 
p 2 
