Greshoff[237] has discovered an amygdalin-like glucoside in the two tropical trees Pygeum parriflorum and P. latifolium. The same author states that the leaves of Gymnema latifolium, one of the Asclepiads, yields to distillation benzaldehyde hydrocyanide. Both Lasia and Cyrtosperma, plants belonging to the natural family of the Orontads, contain in their flowers potassic cyanide. Pangium edule, according to Greshoff, contains so much potassic cyanide that he was able to prepare a considerable quantity of that salt from one sample of the plant. An Indian plant (Hydnocarpus inebrians) also contains a cyanide, and has been used for the purpose of destroying fish. Among the Tiliads, Greshoff found that Echinocarpus Sigun yielded hydrocyanic acid on distillation. Even the common linseed contains a glucoside which breaks up into sugar, prussic acid, and a ketone.
[237] M. Greshoff—Erster Bericht über die Untersuchung von Pflanzenstoffen Niederländisch-Indiens. Mittheilungen aus dem chemisch-pharmakologischen Laboratorium des botan. Gartens des Staates, vii., Batavia, 1890, Niederländisch. Dr. Greshoff’s research indicates that there are several other cyanide-yielding plants than those mentioned in the text.
The following plants, with many others, all yield, by appropriate treatment, more or less prussic acid:—Bitter almonds (Amygdalus communis); the Amygdalus persica; the cherry laurel (Prunus laurocerasus); the kernels of the plum (Prunus domestica); the bark, leaves, flowers, and fruit of the wild service-tree (Prunus padus); the kernels of the common cherry and the apple; the leaves of the Prunus capricida; the bark of the Pr. virginiana; the flowers and kernels of the Pr. spinosa; the leaves of the Cerasus acida; the bark and almost all parts of the Sorbus aucuparia, S. hybrida, and S. torminalis; the young twigs of the Cratægus oxyacantha; the leaves and partly also the flowers of the shrubby Spiræaceæ, such as Spiræa aruncus, S. sorbifolia, and S. japonica;[238] together with the roots of the bitter and sweet Cassava.
[238] The bark and green parts of the Prunus avium, L., Prunus mahaleb, L., and herbaceous Spirææ yield no prussic acid.
In only a few of these, however, has the exact amount of either prussic acid or amygdalin been determined; 1 grm. of bitter almond pulp is about equal to 21⁄2 mgrms. of anhydrous prussic acid. The kernels from the stones of the cherry, according to Geiseler, yield 3 per cent. of amygdalin; therefore, 1 grm. equals 1·7 mgrm. of HCN.
§ 254. The wild service-tree (Prunus padus) and the cherry-laurel (Prunus Laurocerasus) contain, not amygdalin but a compound of amygdalin with amygdalic acid; to this has been given the name of laurocerasin. It was formerly known as amorphous amygdalin; its formula is C40H55NO24; 933 parts are equivalent to 27 of hydric cyanide—that is, 100 parts equal to 2·89.