180 MICROBES AND TOXINS 



venomous at the time of greatest activity of their reproductive 

 glands. 



The Toad (Batrachia) manufactures poison in its parotid 

 gland and the glands of the skin, but it has no other way of 

 secreting it than by contracting its skin and covering itself with 

 a viscous, nauseating slime, which is rather poisonous when 

 injected into small animals such as mice. Phisalix and 

 Bertrand have extracted two poisons from the toad, ' bufotaline ' 

 and ' bufotenincj a poison of the nervous system. At spawning 

 time the cutaneous glands of the male toad are full of venom, 

 whereas those of the female are empty; but the poison 

 accumulates in her eggs, from which it may be extracted by 

 means of chloroform. 



The Salamanders possess on their sides and tail poison 

 glands, and it is to the fluid which these secrete that they owe 

 their fame as animals capable of living in fire and even 

 of extinguishing it pure legend, of course. Their secretion 

 permits, at most, of their surviving a few seconds. 



One venomous animal exists among the mammals, the 

 Ornithorhynchus. Its poison gland is situated on its thigh, 

 and the secretion escapes by a spur or claw on the hind feet. 

 The poison resembles that of the snake Lachesis^ but is much 

 more feeble. 



Medical men have been especially attracted to the study 

 of snake-venoms. The vipers of our own country have few 

 victims, but in India the cobra kills as many as an epidemic 

 disease. In 1889, in India, 22,480 human beings and 3,793 

 domestic animals died of snake-bite. Of those bitten 25 to 30 

 per cent, die within *ten or twelve hours. The importance 

 is obvious of the researches which led to the antivenom 

 serotherapy (Calmette). 



As they issue from the glands the venoms resemble a thick, 

 oily saliva more or less yellow. Their physical properties vary 

 a good deal with the genus. The venoms of the Viperidae 

 do not dialyse through a membrane and are destroyed entirely 

 at 75 to 80 C. (Lachesis even at 65). Those of the 

 Colubridae pass slowly through vegetable membranes, with 



