ACTION ON THE CELLULAR ELEMENTS OF THE BLOOD. 185 



SUMMARY. 



The subcutaneous injection of solutions of heloderma venom in quantities 

 varying from 5 to 27.5 mg. into a series of 16 non-immunized, apparently 

 healthy rabbits of an average weight of 1,500 grains, led in many cases to a rise 

 in the number of leucocytes within the 24 hours following the injection. This 

 rise in the number of leucocytes was frequently preceded by a slight fall. This 

 rise in the number of leucocytes was not noticeable in all cases; it was absent in 

 several cases, in which relatively large quantities of venom had been injected. 

 It was also absent in three cases in which the animals died a few hours after the 

 injection. In one of these rabbits the injection was followed by a marked fall 

 in the number of leucocytes. 



In two healthy, non-immunized dogs, non-lethal doses of venom admin- 

 istered partly or entirely intravenously were followed by a leucocytosis that 

 was noticeable as early as 2 hours after the injection and persisted at least a day. 

 The increase in the number of leucocytes was in all cases due to an increase in 

 the polymorphonuclear neutrophiles or pseudoeosinophiles. In contradistinc- 

 tion to ordinary rabbits, a rabbit that had gained a certain degree of active 

 immunity through frequently repeated injections of gradually increasing doses 

 of venom showed a very marked leucocytosis following the successive injections 

 of 55 and 60 mg. respectively of the venom. In this animal there seems to 

 been a slight but constant increase in the number of leucocytes. After the 

 injection of 55 mg., an increase in the number of leucocytes appeared 2 hours 

 30 minutes after the injection, 4 hours 45 minutes after the injection the increase 

 was greater, and was very high 22 hours after the injection. After administra- 

 tion of 60 mg. of venom, the leucocytosis was observed a day after the injection 

 and seemed to persist about 24 hours. On two later occasions, when large 

 doses of the venom (70 and 80 mg. respectively) were given, repeated examina- 

 tions of the blood during the succeeding 4 days did not show the presence of a 

 leucocytosis. There can be little doubt that the injection of large doses of 

 venom during the process of immunization increased very markedly the leuco- 

 cytosis following the administration of venom. 



Whether this leucocytosis depends on an actual increase in the number of 

 leucocytes or on an unequal distribution of leucocytes in the various regions of 

 the body must at present be left undecided. 



Injection of venom into rabbits or dogs has no marked effect on the num- 

 ber of erythrocytes or quantity of hemoglobin in the circulating blood. 



