SNAKE-BITES AND POISONOUS FISHES. 115 



the poison glands so that the venom is forced down the duct into the tooth 

 and injected into the wound. The firmer the hold obtained, the greater the 

 quantity of venom injected, and the greater the danger. 



Non-poisonous snakes also have rudiments of this gland, which secretes » 

 poison not in sufficient quantities to be harmful, but sufficient to render them 

 resistant to the toxic effects of other poisonous snakes when bitten. (Fraser.) 



In 1890 Prof, Fraser asserted that the serum of poisonous snakes 

 possesses antitoxic powers, and presumes, that this was acquired by the 

 snake swallowing its own venom. Cunningham later disproved this, showing 

 that the natural immunity of the snake is quite distinct from the artificial 

 immunity, which is established in other animals as the result of continued 

 cumulative treatment by cobra venom, and that it is unconnected with any 

 material of the nature of an antitoxin. He found that cobra serum had no 

 antidotal effect on Daboia venom ; he does not therefore believe that the 

 immunity of snakes is due to the swallowing of their own venom. 



The fact, however, remains, that most reptiles and amphibians possess a 

 high degree of resistance as a natural property, quite independent of any 

 process of self-prctection. One of Cunningham's snakes readily resisted an 

 amount of cobra venom enough to kill one hundred fowls, yet its serum had 

 no protective power ; its blood indeed was highly toxic for one week after, 

 enough to rapidly kill a fowl when injected. 



The immunity of snakes to venom of other and the same species is not 

 absolute though general, for I have seen a Daboia russelli in captivity attack 

 a second in the same cage, which was found dead soon after. Also any one 

 who has seen a fight between a hamadryad and a rat snake " Dhamin '' of 

 equal or larger size will remember the gradual poisoning of the latter, which 

 nevertheless meanwhile inflicts much local injury on the less powerfully 

 toothed but successful adversary. A species of Bungarus or " krait " of 

 Scinde will kill and swallow the very venomous " f ursa " or Echis 

 carinata. Cunningham further believes that the degrees of susceptibility to 

 some extent run parallel with the respiratory acquirements, the slow-breath- 

 ing, hybernating reptiles and lizards having the greatest resisting power. 

 The mongoose is remarkably resistant to cobra poison, requiring from 10 to. 

 25 times as much venom per kilo as a rabbit to produce lethal effects. Elliot 

 believes that the success of this animal fighting cobras depends on (1) its 

 great agility, (2) its habit of " setting up " its fur, thus deluding the snake 

 as to the vulnerable part. Its immunity is due to the habit it has of seizing 

 the snake by the head, and often by so doing incising the gland with its 

 sharp teeth, causing the venom to escape and be swallowed by the mongoose ; 

 this would also reduce the possible amount to be injected down the fang. 

 Then there is the inoculation of minute quantities of venom from repeated, 

 but ineffectual, scratch -bites. In these ways a partial immunity, which is 

 hereditary, is established, becoming lost in time if the animals be removed: 

 to countries where cobras do not exist. 



