SCORPIONIDEA 



209 



indicate the presence of toxins, one resembling the neurotoxin of 

 snake-venom, and another a hsemolysin, for Kyes has described a 

 typical lecithide producing haemolysis like the lecithides of cobra- 

 venom. Calmette has also shown that the venom of Buthus occi- 

 fanus is neutralized by cobra antivenene. There would, therefore, 

 appear to be some resemblance between scorpion-venom (or, at all 

 events, the venom of Buthus occitanus) and cobra-venom. It is, 

 however, impossible to make any definite statements, as the 

 condition of our knowledge with regard to this poison is most 

 unsatisfactory. 



Iwano says that the poison is a protein, of which there are two 

 kinds, one soluble in water and the other in dilute acids, and from 

 these crystalline bodies can be prepared. Lecithin and cholesterin 

 are also present in the venoms, which can be destroyed by pepsin 

 and trypsin, permanganate of potash, and calcium hypochlorite. 

 It seems to be very like snake-venom, and it is time that researches 

 on modern lines were made. 



Joyeux-Laffine thought that the venom first increased reflex 

 action, and then caused paralysis of the nervous system, and that 

 death was due to a curari-like poisoning of the end-plates of the 

 respiratory muscles; but Valentin found these were quite intact, 

 and that the muscles contracted well when their nerves were 

 stimulated by electrical or mechanical stimuli. 



As regards the action on the blood, coagulation, haemorrhage due 

 to change in the capillary walls, and haemolysis have been observed, 

 as well as agglutination of the red corpuscles, which are said to form 

 viscous masses, and thus to block the bloodvessels by embolism. 



These observations were made by Jousset de Bellesme on Lilla 

 viridis, a frog remarkable for its lack of pigment, and therefore 

 specially suitable for such a purpose. If confirmed, they would 

 show the presence of fibrin ferment, hsemorrhagins, haemolysins, 

 and agglutinins in scorpion-venom, and would make it resemble 

 very closely snake-venoms. Sanarelli, however, was not able to 

 observe any change in the red cells beyond haemolysis, which he 

 saw in the blood of fishes, amphibia, and birds. 



In conclusion, we may therefore assume the presence of a neuro- 

 toxin acting on the central nervous system, and the presence of 

 haemolysins, until further experiments give us more exact information. 



Minimum Lethal Dose. — The minimum lethal doses for dry 

 Buthus afer venom is, according to Calmette, 0-05 milli^,ramme for 

 white mice, and 0-5 milligramme for rabbits. 



That the venom must be very toxic for small animals is shown 

 by the fact that the minimum lethal dose for a guinea-pig is o-i 

 milligramme per kilogramme, which gives a toxic value of 10,000,000 

 for Buthus quinquestriatus ; but, as may be imagined, the toxicity 

 of different venoms varies considerably, and the difference may be 

 not merely quantitative, but qualitative. 



Effects of the Venom. — It must be remembered that the venom 

 is not merely a means of defence for the scorpion, but it is also the 



14 



