CHAPTER XII 



THE PRODUCTION OF POISON IN PLANTS 



THE USE AND ACTION OF POISONS ON PLANTS 



An extraordinarily large number of poisonous substances belonging to the 

 alkaloids, glucosides, saponins, and toxins, occur in the vegetable kingdom- In 

 addition there is a larger number of substances not strongly poisonous which 

 are curative in their nature. These substances so widespread in the vegetable 

 kingdom are the products of metabolism and probably in some cases, waste 

 products, although according to Weevers, may act as reserve food substances. 

 Treub x states that the hydrocyanic acid in the Pangium edule is of importance 

 in the metabolism of the plant. It occurs not only in certain parts of the fibro- 

 vascular bundle but in the cells from the leaf and certain specialized cells of 

 the epidermis, occurring both in a free and in an unstable combination. His con- 

 clusion is that the hydrocyanic acid is the first recognizable product of nitrogen 

 assimilation. It is certainly true that in some cases the poisonous products 

 formed in the plant do not undergo any further change. Undoubtedly the sub- 

 stances serve as a protection to the plant and it may be interesting to note that 

 large quantities of these substances may be excreted and occur in an insoluble 

 form in the cell sap and do no injury to the plant- Digitalin, morphin, atropin, 

 eserin, muscarin, and veratrin, seem to exert little or no poisonous action on 

 most plants ; while strychnin may act as a strong poison. 2 There are also other 

 alkaloids that when applied to the plant are poisonous to the plants from which 

 they have been obtained. Morphin is said to poison the poppy, and the motile 

 spores are speedily killed by the same substance according to Strasburger. Too 

 little, however, is known about this subject to make any extended remarks. It 

 is interesting, however, to observe in this connection that as in the case of man 

 and other animals, plants can be gradually accustomed to doses which would 

 probably prove fatal in many cases. The Blue Mould (Penicillium glaucum) and 

 some species of Aspergillus can accommodate themselves to strong solutions of 

 copper and formalin. There are some reasons for believing that the proto- 

 plasm of different plants is not a uniform substance but varies, and that one 

 substance may be toxic to the plant while harmless to another and even act as 

 a stimulant- 



DISTRIBUTION OF POISONOUS SUBSTANCES IN PLANTS 



The seed may contain a toxic substance and upon the germination the 

 poisonous material may occur not only in its juvenile stage but at maturity. 

 In some cases the seed and the juvenile form may be non-poisonous, but as 

 the plant becomes older the poisonous substance is elaborated as in the latex 

 of some plants that contain narcotic principles. In some cases the seed is 

 poisonous and the young plants apparently do not contain a toxic material; the 



1 Ann. du Jardin Bot. de Buitenzorg 13. Pharm. Review. 14:278. 



2 Pfeffer, Physiology of Plants. English Translation. 2:260; Schwarz, WIrkungen von 

 Alkaloiden auf Pflanzen, Erlanger Dissertation. 1897. 



