ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
405 
of the summer, remain alive till the following spring or summer ; the 
other set comprises those leaves which fall and die soon after attaining 
their reddish tint. The latter class of leaves, at the time when they 
assume their autumn tints, contain more sugar and less starch than at 
midsummer. 
The red sap is formed either in the epiderm or in the palisade-cells, 
and in those which line the air-chambers of the leaf. The author 
believes the pigments to be probably of the nature of glucosides, in 
most cases compounds of tannins with sugar. In many plants they can 
be produced at any time of the year by feeding them with glucose. 
Hydrocyanic Acid in Plants.* — M. A. Hebert finds traces of hydro- 
cyanic acid in the red and black currant, and in Uibes aureum (young 
green shoots), embryo of Eriobotrya japonica (Rosacem), and Aquilegia 
vulgaris (leaves, stalks, and buds at the commencement of the period of 
vegetation) ; but not sufficient to constitute a means of defence. 
Hydrocyanic Acid in the Amygdaleae.f — Herr A. J. van de Ven 
finds the quantity of hydrocyanic acid in the branches of the cherry- 
laurel to decrease with increase of age. The root gave very little 
evidence of the presence of hydrocyanic acid. In the youngest leaves, 
just unfolded, the acid occurs only in isolated groups of cells along 
the principal veins, the proportion reaching, in the early summer, as 
much as 2*4 per cent. The amount of the acid in the leaves is 
decidedly increased by strong insolation. The author was unable to 
find any trace of hydrocyanic acid in Vicia sativa or other species of 
the genus, or in Aquilegia vulgaris , where it had been stated to exist. 
Dextrin as a Reserve-substance.}:— From an examination chiefly 
of the bulbs of the hyacinth, M. Leclerc du Sablon ascribes to dextrin 
several different functions in the life of the plant, viz. : — (1) In reserve- 
organs in the process of formation it is an intermediate substance in 
the production of starch ; (2) While the reserve-substances are under- 
going digestion, it is a product of the decomposition of starch ; 
(3) During the dormant period, it is a reserve-substance properly so- 
called independently of starch. 
(3) Structure of Tissues. 
Wood of Pome8e.§— In a further instalment, Dr. A. Burgerstein 
contrasts the histological characters of the wood of the Pomese with 
that of the Amygdalese. He finds no one general character by which 
the two can in all cases be distinguished. In both families 'special 
characters occur in some, but are absent from other species of the 
same family, or even of the same genus. 
“Bicollateral” Vascular Bundles. || — According to Prof. J. Ba- 
ranetzky, there ar^ no such things as true bicollateral vascular bundles. 
* Bull. Soc. Chim., xix. (1898) pp. 310-3. See Journ. Chem. Soe., 1899, Abstr., 
ii. p. 377. f Arch. Neerl. Sci. Ex. et Nat., ii. (1899) pp. 383-96. 
X Comptes Rendus, cxxviii. (1899) pp. 914-5. 
§ Verhandl. k. k. Zuol-bot. Ges. Wien, xlix. (1899) pp. 28-32. Cf. this Journal, 
1898, p. 641. 
|| S.B. bot. Sect. Naturf.-vers. Kiew, Aug. 26, 1898. See Bot. Centralbl., lxxvii. 
(1899) p. 106. 
1899 2 E 
