DERMAL SECRETION. 31 



howling and rubbing its foaming mouth on the grass. 

 After a few minutes the dog was seized with convul- 

 sions, and had to be carried home exhausted. On the 

 next day it had a swollen mouth and burning nose. It 

 did not completely recover until the following day. 



That the toad's poison does not protect it against 

 snakes is well known, — our common Tropidonotus, for 

 instance, not feeling any more repulsion for it than for 

 a frog, although it will not eat Bombinator. It is the 

 experience of those who have handled freshly caught 

 specimens of the latter that the secretion of these 

 Batrachians acts as a sternutatory, and causes irritation 

 of the mucous membrane of the nose and conjunctiva, 

 the effect being comparable to the early stages of a 

 cold in the head. German violinists, it is said, when 

 suffering from moist hands, are accustomed to check 

 the perspiration by handling live toads. Many col- 

 lectors of Batrachians have learned, to their discom- 

 fiture, how the introduction of examples of certain 

 species in the bag containing the spoil of their excur- 

 sion may cause the death of the other prisoners, and 

 common tree-frogs are stated to have died from the 

 contact, in the same small terrarium, of examples of an 

 American species, Hyla versicolor, which, owing to its 

 warty skin, is often designated as a " tree-toad ; " for 

 although the poison has no effect on the skin of 

 individuals of the species which produces it, frogs of 

 different species, however closely allied, may poison 

 each other by mere contact. When ingurgitated or 

 inoculated the poison acts even on the individual by 

 which it has been secreted, as has been proved by 

 various experiments, but death is only produced by 

 using a stronger dose than is required for killing 

 individuals of another species. 



The poison of Batrachians, unlike that of snakes, 

 is not a septic, but acts upon the heart and the central 

 nervous system. That of the common toad has beeu 

 compared, as regards its effects, to Digitalis and 

 Erythrophlaeum. For a long time authorities disagreed 



