534 GENERAL CHARACTERS OP REPTILES. 



destined. These glands (0, Fig. 311) are placed under the 

 temporal muscles, so as to be compressed by their contrac- 

 tion ; and this tooth, which is 

 larger than the others, is some- 

 times pierced by a canal, and 

 sometimes only channelled by 

 a furrow ; but in both cases, 

 the canal which it presents is 

 in communication with the 

 s excretory duct of the poison- 



FIO, 3ii. POISON APPARATUS OF RATTLE- gland, and serves to convey the 



v, poison gland, th^e duct terminates in Ven0m to the bott m f the 

 the large movable tooth, c , m, muscles wound which is made by the 

 which elevate the lower jaw, and serve also , . . ,. 



to compress the gland ; s, salivary glands ; tooth itselt. IhlS venom IS one 



n, nostrils. O f the most violent of poisons. 



It is neither acrid nor burning ; it only produces on the tongue 

 a sensation analogous to that occasioned by a fatty matter, and 

 may be swallowed with impunity ; but, introduced in sufficient 

 quantity into a wound, it produces death with frightful rapidity. 

 Its power varies with the species, and according to the circum- 

 stances in which the Serpent is found. The same species appears 

 to be more dangerous in warm, than in cold or temperate coun- 

 tries ; and the results produced by its bite are much more severe, 

 in proportion as the poison flows more abundantly into the 

 wound. Further, these animals are much more formidable, 

 when they have fasted some time, and when their venom is 

 collected in a considerable quantity in the glands in which it is 

 secreted ; than when they have bitten several times, and there 

 can only remain a small quantity of this liquid. It has also 

 been remarked, that their bite does not act in the same manner 

 upon all animals. It appears that to Leeches, Slugs, the Asp, 

 the Common Snake, the Slow-worm, &c., the venom of the 

 Viper is not a poison ; whilst it produces death with great rapi- 

 dity in all warm-blooded animals, Lizards, and the Viper itself. 

 In general the quantity of venom necessary to produce death is, 

 other things being equal, in proportion to the size of the animal 

 wounded ; thus whilst a hundredth of a grain of the venom of 



