238 BOTANICAL GAZETTE [MARCH 
extract. It is here that the author finds a function for catalase. The extract 
is rich in catalase, and sincé no other function for this enzyme is known, he 
makes it the active agent in the first step of fermentation according to the 
scheme. Nor is this view reached without apparent experimental evidence. 
Extracts of yeast rich in catalase were allowed to act for various lengths of 
time on 10 per cent glucose solutions. The solutions were found to contain 
lactic acid, which was identified by its zinc and calcium salts and by other 
tests. Unfortunately the experiments are not entirely convincing, since the 
only precaution to insure sterility was the addition of thymol to the flasks. 
It is not recorded that cultures were made from the flasks at the end of the 
experiments to demonstrate their sterility. The finding of oxalic acid in the 
flasks would seem to add to the doubtfulness of the experiments. 
Kusserow;' believing that no description of the mechanism of fermenta- 
tion has been given, propounds a new theory of alcoholic fermentation. This _ 
theory is that the demand of the yeast cell for oxygen results in the reduction 
of glucose to sorbite, a molecule of water being involved in the reaction. The 
sorbite breaks up directly into alcohol, carbon dioxid, and hydrogen. The 
hydrogen reduces a further molecule of glucose, and so the process goes on. 
The view is scarcely supported by evidence, nor would the dearth of theories 
alone seem to warrant it, for several have been proposed.—H. HasSELBRING. 
Vegetative reproduction in Metzgeria.—Evans? has described the gemmae 
of 12 species of Metzgeria. They fall into three groups, depending upon their 
position on the thallus. The first group (5 spp.) has the gemmae marginal; 
the second (6 spp.) has them on the antical surface of the wings; and in the 
third group (x sp.) they are indefinite in position. When a gemma is to be 
produced, a marginal cell projects beyond its neighbors and its outer wall is 
ruptured. The protruding protoplast is not naked, however, but is covered 
by a thick layer of transparent gelatinous substance, which EVANS thinks 15 
a modification of the inner portion of the original wall. Upon the inner SUT 
face of this gelatinous substance a very thin new wall soon appears. : 
projecting cell divides by a periclinal wall; the outer of these two cells is con- 
sidered to be the mother cell of the gemma. A second wall meets the first, 
obliquely cutting off a wedge-shaped apical cell, which proceeds to cut 
Segments right and left. The original gelatinous substance becomes stretched 
by the growth of the gemma until it finally disappears. The gemma 8 SM 
rated from the plant by the splitting of the original periclinal wall. Along 
the margin of the young gemma hooked hairs appear. As it becomes older, 
new hairs appear, which function as rhizoids. The young gemma shows no 
sign of dorsiventrality, 
* Kusserow, R., Centralbl. Bakt. II. 26:184-187. 1910. f 
9 Evans, ALEXANDER W., Vegetative reproduction in Metzgeria- Annals 0 
Botany 24:272-303. figs. 16. 1910. 
