1 08 SCIENCE FROM AN EASY CHAIR 



often been stung become in many cases immune, and do 

 not suffer from bee-sting. Men who in France pursue 

 a business as viper-catchers, are said to become immune 

 to viper's poison in the same way Snakes and scorpions 

 are but little, if at all, affected by their own poison when 

 it is injected into them. This appears to be due to the 

 fact that the poison-producing animal is always absorb- 

 ing into its blood very minute doses of the poison which 

 it has elaborated and stored up in its poison-sac con- 

 nected with the poison-gland. This small quantity of 

 poison continually absorbed is continually converted into 

 an anti-toxin just as happens when a horse is treated 

 with doses of snake-poison to prepare the remedial anti- 

 toxin for use in cases of snake-bite, or with diphtheria- 

 poison in order to prepare the diphtheria anti-toxin now 

 so largely used. The anti-toxin is a substance very 

 closely similar in chemical constitution to the toxin by 

 the conversion of which it is formed in the blood. Its 

 action on the toxin (or essential poisonous substance of 

 the venom) appears to be a very delicate and slight 

 chemical disturbance of the constitution of that chemical 

 body. Yet it is enough to cause the injurious quality of 

 the toxin to be suddenly and completely abrogated, 

 although from the point of view of chemical composition 

 it is only, as it were, shaken or given a twist ! Such 

 great practical differences in the action on living creatures 

 of chemical bodies having themselves so subtle a differ- 

 ence of chemical structure as to almost defy our powers 

 of detection, are now well known. 



I made some experiments a few years ago on the 

 poison of scorpions, which were published by the Linnaean 

 Society. I obtained live scorpions a beautiful citron- 

 coloured kind, of large size from Biskra, in Algeria 

 (Fig. 15). The poison-gland and sac are double, and 

 contained in the last joint of the tail, which is swollen, 



