108 THE VENOM OF HELODERMA. 



Furthermore, we have in a few experiments injected in one dose a large 

 quantity of venom intravenously, while the sodium-chloride solutions were 

 being infused at the usual rate. The rabbit was infused in the usual manner 

 with a 0. 85 per cent sodium-chloride solution ; after several hundred cubic centi- 

 meters of this solution had been infused, when the blood-pressure was high and 

 the diuresis markedly increased, the infusion was stopped for a few moments 

 while the venom solution was injected directly into the jugular vein. The in- 

 fusion was then continued as before, with 0.85 per cent sodium-chloride solu- 

 tion. In one experiment the rabbit was infused with venom-adrenalin-sodium- 

 chloride solution instead of sodium-chloride solution, both before and after the 

 injection of venom was given. 



As stated above, the injection was given at a time when the blood-pressure 

 was either higher than usual or nearly normal and when the diuresis was 

 marked. Immediately following the injection we observed a marked fall of 

 blood-pressure, which was 24 mm., 62 mm., and 89 mm. of mercury in the three 

 cases respectively. Following this very marked lowering of the blood-pressure 

 it rose again 10 to 18 mm. during the inflow of the next 100 c.c. of fluid. When 

 a pure sodium-chloride solution was infused both before and after the injection 

 of the venom, the blood-pressure continued from there on at about the same 

 level (still quite markedly below the normal) until the end of the experiment 

 (see figs. 22 and 23). When adrenalin- venom-sodium-chloride solution was 

 infused both before and after the sudden injection of the venom, the pressure 

 fell again after the first rebound but later rose very gradually (see fig. 24). 

 In this latter case it is probable that exhaustion prevented the blood-pressure 

 from rising as much as it did in cases in which pure sodium-chloride solution 

 was infused. 



The diuresis curve shows a very marked fall simultaneously with the fall of 

 blood-pressure. In experiments in which a pure sodium-chloride solution was 

 used in the period directly following the rapid injection of the venom, only 6 to 

 10 c.c. of urine were secreted during the infusion of the first 100 c.c. of fluid. 

 As the blood-pressure now became gradually higher, the secretion of urine also 

 increased, 20 to 60 c.c. of urine being eliminated, while 100 c.c. of fluid were 

 being infused. In the experiment in which venom-adrenalin-sodium-chloride 

 solution was infused the decrease in the diuresis, as well as in the blood-pressure, 

 was not as marked as in the experiments in which pure sodium-chloride solu- 

 tion was infused. The presence of the adrenalin in the infused fluid diminished 

 probably to some extent the fall of blood-pressure and decrease in diuresis. 



The rapid injection of venom produces a fall of blood-pressure much more 

 marked than after the continuous infusion of the dilute solution of venom. 

 Accompanying this fall of blood-pressure, the secretion of urine is very markedly 

 diminished. As the pressure gradually rises the diuresis becomes again more 

 pronounced. 



It is of interest to note that the quantity of venom injected in two cases, 

 namely, 12 mg., would be a fatal dose if injected intravenously into a rabbit 

 under normal conditions, while the 36 mg. which were injected in the other 



