620 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
especially when stored up in the testa of the seeds, it serves to protect 
the part against the attacks of animals, and also as an antiseptic agent. 
The immense quantities in which it is stored up in the rhizome of Iris 
jpseudacorus and sibirica, and especially in the spots where adventitious 
roots are about to be formed, appears to indicate that it is, at least in 
these cases, something more than a mere product of excretion, and is 
used up again in the process of metastasis. 
Anthocyanin.* * * § — Prof. D. Levi-Morenos has investigated the antlio- 
cyanin which is the colouring matter of the dark dots on the leaves of 
certain species of Sedum , e. g. S. album , especially in the epidermal 
cells in the neighbourhood of the stomates. The function of this 
colouring matter appears to be protective, in preventing the too powerful 
action of the rays of light. 
Localization of the Principles of Hydrocyanic Acid-t — M. L. 
Guignard refers to the production by certain plants of hydrocyanic acid, 
due to the action of emulsin or synaptase on amygdalin in the presence 
of water. He now describes the localization of the principles of hydro- 
cyanic acid in the almond and cherry-laurel. Emulsin is found in the 
almond in the pericycle, and in the vascular bundles of the cotyledons ; 
while in the cherry-laurel, the pericycle being sclerotized, it is found 
in the endodermal sheath. The presence of emulsin may be determined 
by Millon’s reagent, or by sulphate of copper ; with the former a red 
coloration is obtained, and with the latter a violet. 
Distribution of Chemical Substances in Plants.^ — Herr E. Schar 
gives an exhaustive summary of what is known with regard to the dis- 
tribution of the various chemical substances in the vegetable kingdom. 
These he treats under the head of — I. Generally distributed substances, 
such as the inorganic constituents, carbohydrates, acids, and pigments. 
II. Specific vegetable substances ; the latter being again classified under 
the following seven heads: — (1) Alkaloids; (2) fatty acids; (3) acids 
of the aromatic series; (4) phenols, chinones, and ketones (benzol, 
naphthalen, and anthracen series); (5) essential oils; (6) specific pig- 
ments ; (7) glucosides (such as digitalin and santalin) and bitter sub- 
stances. He points out the remarkable fact of the complete absence or 
great rarity of alkaloids in very large sections of the vegetable kingdom, 
such as the Vascular Cryptogams, the Gymnosperms, the Monocotyledons, 
and the orders Composite and Labiatae. 
(3) Structure of Tissues. 
Transformation of Epiderm.§ — Herr E. Heinricher describes a 
peculiar development of the inner layer of the epiderm of the capsule 
in Adlumia cirrhosa (Fumariaceae). It becomes converted, as the fruit 
ripens, into a layer of mechanical fibre-cells, with narrow or transversely 
oval dots ; they broaden out at their apex, and their walls are uniformly 
* Nuov. Giorn. Bot. Ital., xxii. (1890) pp. 79-80. 
t Journ. de Bot. (Morot), iv. (1890) pp. 3-12, 21-7 (4 figs.), and Comptes 
Bendus, cx. (1890) pp. 477-80. 
X Vierteljahrsckr. Naturf. Gesell. Zurich, 1888 (1890) pp. 323-78. 
§ SB. Akad. Wiss. WieD, xcix. (1890) 15 pp. and 1 pi. See Bot. Centralbl., xlii. 
(1890) p. 345. 
