492 



Dr. L. Eogers. On the Physiological 



[Mar. 31, 



such a marked degree that, when the venom is administered intra- 

 venously, death results from intravascular clotting, as in the Viperine 

 snakes, while if minimal lethal doses are given subcutaneously death 

 results through paralysis of the respiratory centres. Next we come to 

 the Cobra, another Colubrine snake, and here we find the nerve 

 symptoms quite predominate, although some considerable effect on 

 the blood in the form of reduction of coagulability and dissolution of 

 the red corpuscles still survives, although it now takes quite a second- 

 ary position to the effect on the nervous system. Lastly, we have the 

 Hydrophida?, which, morphologically considered, are but colubrines 

 modified for an aquatic existence, and here we find a practically pure 

 nervous poison, although there still persists a trace of action on the 

 blood if strong solutions of the venom are employed, although it can 

 have no actively poisonous effect. The very slight action found, 

 however, may be of some value to the snake in the following way. 

 We have seen that a l-in-200 solution of the Enhydrina poison has a 

 slight retarding effect on the clotting power of the blood, which would 

 doubtless be more marked in still more concentrated solutions, so that 

 it is highly probable that the pure poison would have the effect of 

 preventing the clotting of the blood at the point of injection of the 

 poison, and so allow of its more ready absorption into the circulatory 

 system through the patent vessels severed by the fang. This will 

 account for the extreme rapidity of the absorption of the poison of 

 the Cobra, for Fayrer showed long ago that if immediately after a dog 

 has been bitten by this snake the fold of skin punctured is raised and 

 freely excised, still the animal dies of the poison. The survival of 

 some degree of action on the blood in the case of the Cobra and the 

 Hydrophida?, although not in itself an important element in directly 

 causing the death of the animal, may nevertheless be of service in 

 causing the venom to be more rapidly absorbed in the way just 

 pointed out. 



Action of the Poison on the Pulse and Respiration. 



We have already seen that in slow poisoning the respirations become 

 more and more laboured until convulsions set in and they quickly 

 cease, while the heart continues to beat for a short time. For the 

 accurate study of the exact effects on the respiratory and circulatory 

 svstems, proper recording apparatus is necessary, but as these were 

 not available, I had to content myself with a record of the rate of the 

 pulse and respiration after the intravascular injection of a large and 

 rapidly fatal dose of the poison into rabbits under the influence of 

 chloroform, with the following results. A dose of 1 milligramme per 

 kilo, weight, or at least twenty times a minimal lethal dose was used, 

 and death resulted in from six to eight minutes, taking the time up to 



