SCIENTIFIC SUMMARY. 
97 
to be deposited and take root in a favourable soil ; of this Mr. Hogg gave 
many illustrations, and showed that although yeast, penicillium , aspergillus , 
and some other well-known fungi, had been separately classed, that never- 
theless they could be made to pass through the same changes, and produce 
ferments that could not be recognized one from the other ; and, therefore, 
difference of form he believed to be entirely due to the soil or nourishment 
supplied, and dependent on such circumstances as whether the growth of 
the fungi takes place in a sickly plant, a saccharine solution, or an animal 
tissue. 
The Function of Leaves. — M. Boussingault has contributed some very 
valuable essays upon the physiological office of the leaves of plants. His 
first series of experiments enabled him to conclude that vegetable essential 
oils exert no deleterious influence on leaves, except oil of turpentine, which 
diminishes the carbonic acid decomposing power of oleander leaves. His 
second series of observations shows us the action of mercurial vapour. When 
leaves are placed under a glass bell with their peduncles immersed in mercury, 
it would appear that they are completely deprived of their power of decompo- 
sing carbonic acid ; but when the leaves are not directly in contact with mer- 
cury, but still exposed to the metallic vapour, the decomposing power is lessened, 
but not completely destroyed. The foregoing experiments were conducted in 
the light ; but the author has proved that leaves kept in the dark in contact 
with mercury transform quite as much oxygen into carbonic acid as a leaf 
similarly placed in confined air will when not in contact with mercury. 
M. Boussingault next describes how he collected the gases evolved 
from the branch of an oleander still attached to the plant. The gas 
escaped from the branch at the rate of 3*3 c.c. per hour, and in twenty- 
three hours there were collected 76*93 c.c. of a mixture having the following 
percentage composition : — Nitrogen, 88*01 ; oxygen, 6*64 ; carbonic acid, 
5*35. This gas, the author says, is similar in composition to that confined 
in strongly manured soil. On reaching the leaves with the sap, it only brings 
carbon to the vegetable organism, or, as the author said at the commencement 
of his memoir, carbonic oxide, hydrogen resulting from the simultaneous 
decomposition of carbonic acid and water. — Vide Comptes Bendus , Oct. 23rd. 
Spiral Vessels. — According to the inquiries of M. Lestiboudois, air, or even 
fluids capable of solidification may be present in the tracheal tubes : in one 
instance he found one of the vessels in the centre of the fibres of Calamus 
Botang filled with a peculiar white substance, arranged in a cylindrical 
manner, and which, when placed in water, became converted into granules, 
which exhibited rapid movement. 
A n International Botanical Congress will be held -in London next May, 
under the presidency of M. de Candolle. Papers intended to be read should 
be sent in before March next to Dr. Seemann, 57, Windsor Road, N., who is 
the Honorary Secretary. The congress will be restricted to two morning 
meetings, and the papers will be accompanied by translations. 
An Australian Poison Plant. — In one of the numbers of the “Proceedings 
of the Royal Society of Victoria,” Mr. F. Muller gives an account of this 
plant, the Gastrolobium grandiflorum. This plant, which has proved so 
detrimental to herds and flocks, is a bush several feet high, bearing orange- 
VOL. V. — NO. XVIII. H 
