ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
301 
rated atmosphere, is effected by pumping-actions proceeding in the living 
cells of the leaves. These pumping-actions are capable of raising the 
water against an external hydrostatic pressure. In common with other 
vital actions, they are accelerated by a moderately high temperature, and 
are dependent on the supply of oxygen. The cells adjoining the terminal 
portions of the water-conduits appear to possess this activity, and in 
plants provided with water-glands the pumping-actions are not limited 
to the secreting tissues of these glands. 
(4) Chemical Changes (including Respiration and Fermentation). 
Formation of Sugar in the Turnip.* * * § — Herr M. Gonnermann has de- 
termined that the formation of sugar in the leaves of the turnip can 
take place only through the action of an enzyme. There are two enzymes 
present in the leaves, an invertase and a diastase, and these are distinct 
from the corresponding enzymes of barley. By their action starch is 
transformed by hydrolysis into products which are again changed into 
saccharose, partly in the leaves, but more completely in the parenchyme 
of the root. 
Decomposition of Glucosides by Fungi.t — Herr K. Puriewitsch 
finds that the mycele of mould-fungi ( Aspergillus niger, A. glaucus , 
Penicillium glaucum ) has the power of decomposing glucosides in just 
the same way as emulsin ; and the spores also have the same property 
when germinating. The resulting substances are glucose and benzol 
derivatives ; the former being taken up by the mycele ; the latter either 
also taken up, or retained in the solution. 
y. G-eneral. 
Biological Species and Races.:]: — Herr E. Rostrup distinguishes 
between the use of these two terms (in Fungi). In the latter, the 
capacity for one form to pass over into another has been only partially, 
while in the former it has been entirely lost. Biological races occur 
in Lophodermium Pinastri ; biological species in the genera Coleosporium 
and Melampsora. In Puccinia graminis are a number of biological 
l aces, each of which is limited to a definite host-plant ; while biological 
species also occur in the same genus. P. coronata , with secidia on 
lihamnus Frangula , and basidial fructification on Agrostis and Calama - 
grostis ; also P. coronifera, with aecidia on P. catharticus, and basidial 
Iructification on Avena and Lolium, are biological species. 
Alternation of Generations. — Prof. G. Klebs § discusses the ques- 
tion of alternation of generations in the Thallophytes, recapitulating 
the views of different authorities. He concludes that the majority of 
Algae and Fungi have two or more kinds of propagation ; but there 
is no reason, in these cases, for speaking of an alternation of genera- 
tions. Such an alternation does, however, occur in the heteroecious 
Uredineae, and in certain Diatoms, if the present theory of the cause of 
* Zeitschr. Yer. Deutsch. Zuckerind., 1898, p. 667. See Bot. Centralbl., Beih., 
viii. (1899) p. 280. 
t Ber. Deutsch. Bot. Ges.. xvi. (1898) pp. 368-77. 
t Bot. Tidskr., xx. pp. 116-25. See Bot. Centralbl., Beih., viii. (1899) p. 298. 
§ Ann. of Bot., xii. (1898) pp. 570-83. 
