SNAKE TOXINES. 219 



VALENTIN 1 found that there was a manifest want of excita- 

 bility in the muscles and nerves of a frog after five hours. 

 The central nervous system was deprived of its excitability 

 sooner than the sciatic nerve endings. 



Thus, general poisoning by snake toxines is due primarily 

 to their action upon the central nervous system, and, above 

 all, upon the motor centres of the medulla. On the other 

 hand, the peripheral nerves are not affected, at all events in 

 the case of the frog (CALMETTE). In this action the neurotoxic 

 component predominates. We shall see presently that this is 

 not the case with all snake poisons, and notably crotalus venom, 

 in which the chief effects are produced by the component pos- 

 sessing hsemorrhagic powers. The hsemolytic component in that 

 venom need not be taken into account here, and will be dealt 

 with separately. 



The fact that neurotoxine is no more active on intercerebral 

 injection than when otherwise introduced shows that it is a 

 specific poison for the central nervous system, and does not 

 combine with cells elsewhere, being monotropic, to use Ehrlich's 

 terminology. 2 



Cobra poison which was free from hsemolysine and heemor- 

 rhagine was injected into the cerebellum by FLEXNER and 

 NOGUCHI (loc. cit.), and it was found that the lethal dose was 

 not less than that required in subcutaneous injection. 



The behaviour of crotalus poison is quite different in this respect, for 

 the lethal dose was twenty times less on intercerebral injection. This 

 venom contains but little neurotoxine, and, in the main, it enters into 

 combination in another way. The great activity of crotalus poison on 

 intercerebral injection is, in fact, due solely to its hsemorrhagic function, 

 and therefore disappears on heating the solution to 75 C., at which tem- 

 perature the haemorrhagine is destroyed. An intermediate position is 

 occupied by the venoms of the mocassin snake and of the ancistrodon, 

 since they contain a large proportion of both components. 



Fresh cobra poison has a very violent action, resembling that 

 of abrine, upon the conjunctiva. The poison can be deprived 

 of this property, however, by being heated to 90 C., which does 

 not materially affect its toxicity. 



No absorption appears to take place thence, such as has been 

 observed in the case of ricine. The same result was obtained by 

 VALENTIN in his experiments with viper venom. 



1 Valentin, "Einige Beobachtungen iiber die Wirkungen des Vipern- 

 giftes," Z.f. Biol, xiii., 80, 1877. 



2 Ehrlich, "Ueb. d. Bezieh. von chemischer Konstitution, Verteilg. u. 

 pharm. Wirkg.," Festschr.f. Leyden, 1902 (reprint). 



