1826,] Proceedings of Philosophical Societies, 137 



Article XII. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



Dec. 22 (continued). — A paper was read, On the Poison of the 

 Common Toad ; by J. Davy, MD. FRS. 



The popular belief in the venomous nature of the Toad, Dr. 

 Davy states, though of great antiquity, has been rejected as a 

 vulgar prejudice by modern naturalists, decidedly so by Cuvier; 

 but hke many other long received and prevalent opinions, it is a 

 true one, and the denial ofit by philosophers has resulted from su- 

 perficial examination. Dr. D. found the venomous matter to be 

 contained in follicles, chiefly in the cutis vera, and about the head 

 and shoulders, but also distributed generally over the body, and 

 even on the extremities. On the application of pressure, this 

 fluid exudes, or even spirts out to a considerable distance, and 

 may be collected in sufficient quantity for examination. It is 

 extremely acrid when applied to the tongue, resembling the 

 extract of aconite in this respect, and it even acts upon the hands. 

 It is soluble, with a small residuum, in water and in alcohol, and 

 the solutions are not affected by those of acetate of lead and 

 corrosive sublimate. On solution in ammonia, it continues 

 acrid ; it dissolves in nitric acid, to which it imparts a purple 

 colour. By combination with potash or soda, it is rendered less 

 acrid, apparently by partial decomposition. As left by evapo- 

 ration of its aqueous or alcoholic solutions, it is highly inflam- 

 mable ; and the residuary matter that appears to give it 

 consistence seems to be albumen. Though more acrid than the 

 poison of the most venomous serpents, it produces no ill effect 

 on being introduced into the circulation ; a chicken inoculated 

 with it was not affected. 



The author conjectures that this " sweltered venom," as it is 

 correctly termed by our great Dramatist, being distributed over 

 the integuments, serves to defend the Toad from the attacks of 

 carnivorous animals: "to eat a toad" has long been held 

 as an opprobrious difficulty ; and the animal is still further 

 protected in this respect by the horny nature of its cutis, which 

 contains much phosphate of lime, &c. As the venom consists 

 in part of an inflammable substance, it is probably excrementi- 

 tious, and an auxiliary to the aption of the lungs in decarboniz- 

 ing the blood. This view of its'use is confirmed by the fact that 

 one of the two branches of the pulmonary artery supplies the 

 skin, its ramifications being most numerous, where the follicles 

 of venom are thickest. 



