ANIMAL POISONS. 539 



and indicate the gummy nature of this poisonous substance. 

 Fontana made a set of experiments on the dry poison of the vi- 

 per, and a similar set on gum arabic, and obtained the same re- 

 sults. 



From the observations of Dr Russel, there is reason to believe 

 that the poisonous juices of the other serpents are similar in their 

 properties to those of the viper. 



This striking resemblance between gums and the poison of the 

 viper, two substances of so opposite a nature in their effects upon 

 the living body, is a humiliating proof of the small progress we 

 have made in the chemical knowledge of these intricate sub- 

 stances. The poison of the viper, and of serpents in general, is 

 most hurtful when mixed with the blood. Taken into the sto- 

 mach it kills if the quantity be considerable. Fontana has as- 

 certained that its fatal effects are proportional to its quantity, 

 compared with the quantity of the blood. Hence the danger di- 

 minishes as the size of the animal increases. Small birds and 

 quadrupeds die immediately when they are bitten by a viper ; 

 but to a full -sized man the bite seldom proves fatal. 



Ammonia has been proposed as an antidote to the bite of the 

 viper. It was introduced in consequence of the theory of Dr 

 Mead, that the poison was of an acid nature. The numerous 

 trials of that medicine by Fontana robbed it of all its celebrity ; 

 but it has been lately revived and recommended by Dr Ramsay 

 as a certain cure for the bite of the rattlesnake.* 



2. The common toad (Rana bufo) has been considered as poi- 

 sonous by the common people in all ages. But the opinion was 

 rejected by naturalists as a vulgar prejudice till the subject was 

 investigated by Dr Davy.f 



This poisonous liquid is seated chiefly in the integuments, in 

 follicles, in the cutis vera beneath the cuticle, and the coloured 

 rete mucosum. These follicles are largest and most numerous 

 near the shoulders and about the neck of the animal ; yet they 

 are pretty generally distributed, and even on the extremities. 

 Pressure being applied to the skin a yellowish thick fluid exudes, 



* Phil. Mag. xvii. 125. The reader will find an interesting dissertation on 

 the different remedies applied to the cure of the rattlesnake in the Amer. Trans. 

 Vol, iii. p. 100, by Dr Smith Barton. The observations of Fontana in his trea- 

 tise on poisons deserve particular attention. 



t Phil. Trans. 1826, p. 227. 



