Effects of Snake Venoms on Plants

Abstract

With the exception of Mitchell 1 and Salisbury, 2 who made sporadic observations on the subject in nature, investigators have given very little attention to the effects of snake venoms on plants. In connection with phytopharmacological studies regarding the effect of various animal poisons on living seedlings, the writer made experiments with suspensions or solutions of snake venoms by dissolving small quantities of the dry scales in physiological saline. The method employed has been fully described. 3 , 4 , 5 Seeds of Lupinus albus are soaked for 24 hours in water and then planted in finely divided sphagnum moss. When seedlings have germinated and borne roots from 30 to 40 mm. long, they are carefully selected, “matched,” and placed in upright, hard-glass test tubes containing a plant-physiological solution made up of equal parts of Shive's mixture and distilled water. The average growth of roots of 10 seedlings (in the dark at 20° C. for 24 hours) is determined. Dry scales of snake venoms were rubbed up with small quantities of physiological saline and then diluted with the plant-physiological solution mentioned above in various concentrations; and the growth of the Lupinus albus seedlings in such solutions was also determined. The relative inhibition of growth of seedlings in the solutions of venom, compared with growth of the controls, is the phytotoxic index and expressed in percentages. The control experiments, as well as the experiments with solutions of venoms, were all made with seedlings from the same crop, grown under exactly the same conditions of temperature, light, weather, etc. Such sets of experiments were made repeatedly so that the conclusions were definite, as will be seen from the figures in Table I. The venoms of the Crotalus atrox, Crotalus exsul, Bothrops atrox, Ankistrodon piscivorus and Naja (cobra) were studied.∗