42 L ; Dr. L. Rogers. On the Physiological Action [Nov. 19,. 



recorded simultaneously with the general blood pressure in the carotid 

 artery, and marked vaso-motor dilatation was observed to take place 

 coincidently with the fall in the general blood pressure, instead of 

 a passive diminution in its volume, which should have taken place if 

 the circulatory failure had been due to a direct action on the heart 

 itself. 



That the vaso-motor affection was central, and not peripheral, was- 

 shown by the fact that both a small dose of Daboia venom (and also a 

 large one of Cobra) produced contraction of the vessels of the limbs 

 through which blood was transfused after separation from the influence 

 of the central nervous system, while adrenal extract and nicotine 

 caused marked elevation of the blood pressure of a temporary nature 

 after complete paralysis of the central vaso-motor centre, as shown by 

 a stimulation of the central end of the sciatic nerve failing to produce 

 any rise of the general blood pressure. 



II. The African Puff-adder. This venom (for which I am indebted 

 to Dr. J. W. W. Stephens) produces intra- vascular clotting like Daboia 

 venom in small animals, but it is much easier to produce the negative 

 phase of lost coagulability, and thus produce death without ny 

 clotting with it, than with Daboia venom itself. The blood-pressure 

 and respiratory curves in such cases resemble in every important 

 essential those of Daboia venom without clotting. Adrenal extract 

 has the same effect in raising the fallen pressure, as does nicotine,, 

 which was suggested to me by Sir Lauder Brunton. Further, a very 

 marked vaso-dilatation of the portal circulation in a loop of the small 

 intestine, coincidently with the fall in the general blood pressure, was 

 recorded. The Puff-adder venom also had a very marked effect in- 

 producing petechial haemorrhages in the peri- and endo-cardium, and in. 

 the mesentery and omentum in particular, which is not at all an. 

 important feature of Daboia poisoning. 



B. Crotalicla'. I. Crotahi-s hwridus, or Rattlesnake : I am indebted to 

 Dr. J. Brunton Blaikie for this venom, the haemorrhagic symptoms 

 produced by which are well known. Blood-pressure and respiratory 

 tracings of the action of this venom showed that the same primary 

 failure of the circulation, as in the former instances, is produced by it,, 

 but without any intra-vascular clotting, except rarely at the seat 

 of injection. The failure of the respiration appears to be secondary to 

 that of the circulation, while the very feeble action of strong solutions 

 of the venom directly on the heart will not account for the facts 

 observed, including the pumping-up of the blood pressure with the 

 occurrence of respiratory convulsions and well-marked and persistent 

 Traube-Hering curves, as with the other Viperine venoms. In this 

 case, again, the dilatation of the vessels of the portal circulation,, 

 coincidently with the general fall of blood pressure, has been both 

 observed under the microscope and demonstrated with the oncometer. 



