INTRODUCTION. 



On the whole, we may conclude that the structural changes (even in the 

 brain) which we find after the administration oTvenom are not the cause of the 

 primary pathologic effects, but either accompany or folIowTHeTatter^^ Eater, 

 however, these functional disturbances may give rise to secondary structural 

 changes, a consideration which probably applies also to the changes which 

 Leopold found in the ganglia-cells of animals injected with poison of Gila 

 monster. 



The effect of the venom of Heloderma upon the cellular elements, as well 

 as upon the coagulation of the blood, is less m arked than those found by pre- 

 vious investigators in the case of the venoms of various snakes. If there exists 

 anj^ effect at all upon the coagulation of the blood, it is certainly very slight. 

 After intravenous injections of extracts of the poison gland of Helodernia,we 

 observed an insignificant retardation in the coagulation of the blood, an effect 

 frequently observed after intravenous injection of various tissue extracts in a 

 quantity too small to cause intravascular clotting. 



The ven om of Heloderma possesses no direct hemolytic action. It becomes 

 hemolytic only in combination with some activators, especially lecithin and 

 certain blood sera, and even here the dose of lecithin necessary for activation 

 is relatively great. In the case of heloderma, as well as cobra venom, the 

 hemolytic is somewhat less heat-resistant than the neurotoxic substance, 

 while the neurotoxin of the venom of Heloderma is somewhat more heat- 

 resistant than that of cobra venom; the hcmolj-sins seem to show approxi- 

 mately the same degree of heat-resistance in both cases. Even in combination 

 with activators the hemolytic property of heloderma venom is comparatively 

 weak as compared to the cobra venom. Moreover, it differs from cobra venom 

 in not being activated by that constituent of fresh serum which is apparently 

 identical with complement. Heloderma venom can be activated by certain 

 blood sera, but the latter then retain their activating power after having been 

 exposed to a temperature that destroys or somehow invalidates the comple- 

 ment. Our knowledge concerning the finer mechanism through which the 

 complement participates in various reactions, or is prevented from participat- 

 ing, is at present too indefinite to make advisable a discussion of the cause of 

 the difference in the behavior of the two venoms ; but we may mention that it 

 may possibly depend merely on a quantitative difference in the hemolytic 

 strength of both venoms. 



Blood-sera not having an activating influence upon hemolysis inhibited it 

 similarly as they inhibit hemolysis by soap or saponin. A certain specific 

 relationship seems to exist between the inhibiting serum and the blood- 

 corpuscles used; in certain cases the hemolysis of the blood-corpuscles of a cer- 

 tain species seems to be inhibited, especially by the serum of the same species. 



A similar relationship has been apparently observed by Besredka in some 

 other connection (Aimales de ITnstitut Pasteur, xv, 1901). Besredka found 

 that sheep serum, for instance, protects only sheep corpuscles against a hemo- 

 lytic rabbit serum and not the corpuscles of another species. This apparent 

 .specific relationship between serum and blood-corpuscles deserves a further 

 study. 



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