ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 343 



tion of this law. The oil is not a result of the degeneration of the 

 protoplasm, but is formed when this substance is in its most active 

 condition. 



Hydrocyanic Acid in Plants.* — Dr. M. Soave concludes, from a 

 series of experiments on the bitter almond and on Pangium edule, that 

 cyanogen compounds are, in plants, transitional substances from which 

 they obtain their nitrogenous food-materials. At the time when the 

 seeds begin to swell, as long as the embryo is dormant, the bitter almond 

 contains no trace of hydrocyanic acid ; it makes its appearance only 

 when the seeds begin to germinate, and then only in the stem, and net 

 either in the root or in the cotyledons. Sweet almonds contain no trac e 

 of amygdalin. 



Formaldehyde in Plants.f — According to Sig. G. Pollacci, when 

 leaves which have been exposed to the light are macerated and distilled 

 with water, the first portion of the distillate contains formic aldehyde, 

 the presence of which was determined by several distinct tests employed 

 by the author. 



Myrosin and Gum in Moringa.J — M. F. Jadin finds, in various 

 organs of Moringa pterygosperma, a ferment formed in special cells, 

 identical with myrosin. The gum which the plant produces is formed 

 in lacunas in the pith of the stem and occasionally of the leaf-stalks ; it 

 is wanting in the flower-stalks and in the root. 



Presence of Molybdenum, Chromium, and Vanadium in Plants.§ — 

 By the use of spectrum analysis, M. E. Demarsay finds traces of these 

 elements in a number of plants examined. 



(3) Structure of Tissues. 



Secretion in Healing-tissue and Duramen. 1 ,! — According to Herr A. 

 Will, the product formed in the interior of the cells in healing tissue 

 is not a gum, but a substance of the nature of bassorin, formed in a 

 special bassorinogenous layer. It is produced out of the substances in 

 solution in this layer, apparently not directly out of starch. The 

 formation of the bassorinogenous layer depends on the vital activity of 

 the plant ; it is not formed in winter, but most actively when the leaves 

 are fully unfolded. The right time for cutting back trees is therefore 

 in the spring. It is not prevented, though somewhat hindered, by 

 covering up the wound with cotton-grease, &c. The black pigment of 

 the duramen of ebony is a secondary product of the secretion of the 

 alburnum. The chemical nature of the contents of the duramen may 

 differ in different forms of cell in the same species. 



Influence of Parasites on the Host-plant.lf — M. C. Sauvageau has 

 taken advantage of the property of all species of Sphacelariacese — a pro- 

 perty confined to this family among Algas — of turning black with eau- 

 de-javelle, in order to determine whether the parasite produces a change 



* Nuov. Giorn. Bot. Ital., vi. (1899) pp. 219-38. 



t Boll. Chim. Farm., xxxviii. pp. 601-3. See Journ. Chem. Soc, 1900, Abstr. ii. 

 p. 160. 



X Comptes Rendus, exxx. (1900) pp. 733-5. § Tom. cit., pp. 90-1. 



|| Arch. f. Pharmacie, cexxxvii. (1899) pp. 369-72. See Bot. Centralbl., lxxxi. 

 (1900) p. 23. \ Comptes Rendus, exxx. (1900) pp. 343-4. 



