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 which 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 hæmolyses 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 Comptes rendus de l Académie 
des Sciences, November 6, 1882. 
2 «“ Ueber die Giftwirkung des Nordafrikanischen Skorpiones,” Zeitschrift für 
Biologie, Bd. xii., p. 170, 1876. 
3 Comptes rendus de la Société de Biologie, 1885, p. 574. 
4 Berliner klinische Wochenschrift, 1903, Nos. 42, 42. 
5 Annales de l'Institut Pasteur, 1895, p. 232. 
