POISONS AND THEIR PREVENTION 183 



which an opportunity is afforded for administering 

 the anti-toxin. Before, however, passing on to 

 the investigations which have culminated in the 

 production of a specific antidote for this terrible 

 toxin, there are a few more details which Calmette 

 has furnished as to its character which are of 

 interest. Serpent venom is characterised not only 

 by its intensely virulent properties, but also by the 

 tenacity with which it retains them under diverse 

 circumstances. Thus it may be stored up for a 

 whole year, and yet at the end of that time be 

 as active as ever; and even after several years, 

 although its toxic powers are somewhat reduced, 

 it still retains them to a very appreciable extent. 



Unlike the bacterial toxins, this venom toxin can 

 stand exposure to considerable temperatures with- 

 out injury to its activity, and that of the cobra 

 only suffers after it has been submitted to 98 

 Centigrade for twenty minutes. Sensitiveness 

 to temperature varies, however, with the snake 

 from which the venom is derived. Thus the venom 

 of the so-called " tiger-snake " of Australia will 

 stand being exposed for ten minutes to from 100 

 to 102 degrees Centigrade, and its virulence only 

 disappears when this temperature has been applied 

 for twenty minutes. The venom of the "black 

 snake," another Australian variety, loses its toxicity 

 at a temperature of between 99 and 100 Centi- 



