278 VENOMS 



and, with a lever-like movement, drives the sting into its body. 

 The victim immediately becomes paralysed and motionless.^ 



The poison-glands of a Scorpio occitanus from the South of 

 France contain about 1 to 10 centigrammes of a toxic liquid, 

 capable of furnishing 10 to 15 per cent, of dry extract. This liquid 

 is decidedly acid ; it reddens litmus paper and is miscible with 

 water. 



Its physiological effects are especially intense in the case of the 

 arthropods upon v/hich the scorpion habitually feeds, and in that 

 of vertebrates in general. Batrachians, fishes, birds, and mammals 

 are extremely susceptible to this poison. Half a milligramme of 

 dry extract injected subcutaneously is sufficient to kill a guinea- 

 pig, and 1 milligramme is lethal to the rabbit. 



In poisoned animals there is first observed a period of violent 

 excitement, accompanied by very acute pains ; these are followed 

 by muscular contractions, and finally by paralysis of the respiratory 

 muscles, as in the case of intoxication by cobra-venom. 



The effects of scorpion-poison, which clearly indicate the 

 presence of a neurotoxin, have been very well described by Valentin, - 

 Paul Bert^ and Joyeux-Laffuie. Kyes' has prepared a lecithide 

 from scorpion-venom, which haemolyses red corpuscles as do the 

 lecithides of cobra-venom, and I myself'^ have established the fact 

 that the antivenomous serum of a horse vaccinated against cobra- 

 venom effectively protects mice and guinea-pigs against intoxication 

 by the venom of Scorpio occitanus; this has been verified by 

 Metchnikoff. There is, therefore, a close affinity between this 

 venom and that of Colubrine snakes. 



^ Joyeux-Laffuie, " Appareil venimeux et venin de scorpion " (Thesis for the 

 degree of Doctor of Science), Paris, 1883 ; and ComiJtes i^endus de VAcademie 

 des Sciences, November 6, 1882. 



- " Ueber die Giftwirkung des Nordafrikanischen Skorpiones," Zeitsclirift filr 

 Biologie, Bd. xii., p. 170, 1876. 



* Comities rendus de la Societe de Biologie, 1885, p. 574. 



^ Berliner Jclinische Wochenschrift, 1903, Nos. 42, 43. 



^ Annales de Vlnstihit Pasteur, 1895, p. 232. 



