74 THE PRINCIPLES OF IMMUNOLOGY 



hemorrhagin. Such sera also contain precipitins for the proteins of 

 the special venoms employed and for the serum proteins of the 

 same species of snake. These are highly but not absolutely specific. 

 The mechanism of venom-antivenin union is probably very closely 

 similar to that of toxin-antitoxin unions of other varieties, although 

 Kyes holds that the former is distinctly in the nature of the chemi- 

 cal reaction between a strong acid and a strong base. 



Scorpion poison is secreted by special glands in the abdomen. In 

 human adults the symptoms are rarely severe, except for marked 

 local reaction, but it is stated that the bite of an African scorpion 

 may kill children. As a rule, the most serious effects are from the 

 subsequent infection of the wounds. Todd was able to prepare a 

 specific immune serum for the poison of scorpions. According to 

 Houssay, scorpion venom acts pharmacologically much as veratrin ; 

 it is a smooth muscle stimulant. He states that serum therapy is 

 useful and specific. 



Spider poison is secreted by glands in the thorax. The common 

 spiders are not venomous, except the " cross spider " whose venom, 

 much weaker in the saliva than in the ovaries, closely resembles 

 snake venoms in chemical properties and agglutinin, and probably 

 contains a neurotoxin. Sachs prepared an antivenin against this 

 venom. Some of the larger spiders are extremely poisonous, par- 

 ticularly the Malmigatte of southern Russia and related species in 

 South America and Africa. Large numbers of cattle have been 

 poisoned with as high as 12 per cent, mortality, but the bite is 

 rarely fatal for man. 



The tarantula produces a poison which operates almost entirely 

 locally, and it is stated that an antitoxin can be produced against the 

 Russian tarantula. 



Centipedes. Certain centipedes secrete a poison in special glands 

 that discharge through the claws, capable of producing considerable 

 local reaction. But one case of fatal poisoning has been reported 

 from Texas, that of a child four years old. 



Bees, wasps, and hornets secrete a poison closely similar for all 

 three. Bee poison contains formic acid and in addition a poison 

 which does not give the usual protein reactions, but is destroyed 

 by proteolytic enzymes ; it resists heat to 100 C., weak acids, and 

 alkalies. The poison contains a hemolysin which operates in much 

 the same manner as does cobra hemolysin. The bite produces 

 marked local reaction, but only in cases of extreme hypersuscep- 

 tibility are there general effects or death. Part of the lack of 

 severity of bee poison is due to the small dose injected, for if col- 

 lected in large amounts and injected intravenously into dogs it can 

 produce death. The resistance of professional bee keepers to the 

 bites is probably due to the fact that repeated bites lead to de- 

 velopment of immunity, although it is possible that the doctrine of 

 the survival of the fittest may play its part. Ants probably pro- 



