1903.] nil if Antidotes of Cohibrine and Viper me Venoms. 4'2l 



of those snakes against whose venoms it has the lesser degrees of action, 

 <ind those which eject a very large quantity of venom. I would suggest 

 that a more generally useful antivenin might possibly be prepared by 

 using a mixture of different Colubrine venoms in the preparation of the 

 .serum. 



Part II. THE VIPERS AND PIT-VIPERS. 



A. The J'iperida'. I. The Daboia Russellii produces intra- vascular 

 clotting in small animals, and loss of coagulability of the blood in 

 man, accompanied by haemorrhages from the bowel, etc. This latter 

 chronic form of poisoning can also be induced in smaller animals by 

 first giving small subcutaneous or intra-venous doses to produce the 

 negative phase of reduced coagulability of the blood, and then larger 

 lethal amounts. As I found that in this way quite rapid deaths with- 

 out any intra-vascular clotting could be caused by intravenous injections 

 of the venom, accompanied by remarkable primary failure of the 

 circulation, I have made a prolonged investigation of this phenomenon, 

 using the venoms of two Vipers and two Pit-vipers, with results of con- 

 siderable interest. The direct application of stronger solutions of the 

 venoms than those used in the experiments when applied directly to 

 frogs' hearts, did not stop their action, while in many of the blood- 

 pressure tracings it was evident that the heart continued to beat 

 regularly during and long after the pressure fall. When the pressure 

 fall was sufficiently rapid to stop the respirations by cutting off the 

 blood supply of the medulla, on the occurrence of respiratory convulsions 

 of asphyxial origin the blood pressure was frequently pumped up again 

 in a remarkable manner and the respirations recommenced. Further, 

 the increased excursions of the pulse during the fall of pressure, and 

 the common occurrence of marked Traube-Hering curves, pointed to a 

 relaxation of the blood-vessels of vaso-motor origin. 



In order to ascertain if the fall in pressure was due to a central vaso- 

 motor paralysis, further experiments were carried out with Daboia 

 venom. In Experiment VIII the spinal cord of a dog was cut in the 

 cervical region, and artificial respiration kept up. A subcutaneous 

 followed by an intravenous dose of the virus was injected, and no 

 sudden fall of pressure occurred, and the heart continued beating for 

 some minutes, proving that the falls previously obtained were not due 

 to direct action of the venom on the heart. In Experiment IX the 

 circulation in the omentum was observed to undergo a very marked vaso- 

 motor dilatation coincidently with the usual fall in blood pressure, while, 

 after this was complete, no further persistent fall occurred when the 

 cervical cord was cut, proving that complete paralysis of the central 

 vaso-motor centre had already taken place. Lastly, a record of the 

 portal blood volume changes, due to the amount of blood entering the 

 vessels of a large loop of small intestine placed in an oncometer. were 



