102 



THE VENOMS OJP CERTAIN THANATOPHIDEJ3. 



to a depressant action of the venom upon the vaso-motor centres in the medulla 

 oblongata, and slightly upon the heart. The tendency to a rise of pressure, as well 

 as the ultimate fall, must be due to some action upon the heart itself or the general 

 systemic capillaries. It seems probable that the rise of pressure in these experi- 

 ments is of capillary origin since the pulse-curves do not indicate increased heart 

 power, and we have already had reason to believe that venom exerts a decided 

 action upon the capillaries themselves to bring about the remarkable ecchymoses 

 found so commonly in cases of poisoning an instance also of peripheral irritation, 

 applicable here, is the effect of venom on the vagi peripheries in causing an in- 

 creased respiration rate. The ultimate fall of pressure seems to be cardiac in 

 origin, since there is an accompanying diminution in the force of the beats. 



SECTION II. THE ACTION OF VENOM GLOBULINS UPON THE BLOOD PRESSURE. 



The Action of Venom Globulins upon the Blood Pressure of Normal Animals. 

 Thirteen experiments were made with the globulins upon normal animals. The 

 doses usually given were those representing the amount of globulin in 0.015 

 gram of dried venom. The results of all of these experiments indicate that all 

 the globulins exert an action analogous to that of the pure venom, but that they 

 exhibit a material difference in the relative degree of their toxicity. 



Of the thirteen experiments, seven were made with the water-venom-globulin, 

 two with the copper-venom-globulin, and four with the dialysis-venom-globulin. Of 

 the first series, five were made with the globulin from the Crotalus adamanteus ; one 

 with that of the Ancistrodon piscivorus, and one with that of the Cobra. The second 

 and third series were made with globulins from the Crotalus adamanteus venom. 



The water-venom-globulin produces the most profound changes, causing a primary 

 diminution of pressure almost equalling that produced by pure venom, while 

 dialfjsis-venom-globidin comes next; the copper-venom-globulin has but little 

 effect. The actions of all of these globulins is to cause a primary fall of pressure, 

 which is followed by a rise towards the normal and more or less well marked, 

 while if the dose is sufficiently large the rise is followed by a fall to zero at death. 



In one experiment made with the globulin from 0.035 gram of dried Cobra 

 venom there was no appreciable effect. This was probably due to the very small 

 proportion of globulin in this variety of venom. 



Pressure 

 m. m. 

 110 



80 



92 



90 



84 



84 



95 



96 

 104 



REMARKS. 



Injected intravenously 0.0012 gram water-venom-globulin 

 (= 0.015 gram dried venom) from the dried venom of the 

 Crotalus adamanteus. 



