328 REPTILIA 



Poisonous Reptiles. — With the exception of the beaded Lizards, 

 the Lacertilia are not poisonous. A Bornean Lizard, Lanthanotus, 

 is suspected of being poisonous. Heloderma produces painful 

 swellings in man, but its venom has no hemolytic action. 



The salivary glands of Snakes are differentiated into organs for 

 the formation of powerful poisons. In the Australian black snake 

 they act on the bloody causing intravascular clotting; some of this 

 class also contain hemolytic substances. The arterial and venous 

 walls are broken down and the blood oozes out. Gangrene may set 

 in. Cytolysins act on red cells, white cells and the endothelium of 

 the blood vessels. 



The other class, typified by the cobra, cause a paralysis of 

 respiration. According to Cushney and Yagi, the action of cobra 

 venom is like that of curare in that it paralyzes nerve endings. 

 Noguchi states that in the case of cobra venom toxic action must 

 be ascribed to neurotoxin. Poisoned animals suffer from motor 

 paralysis. 



The chief local effect produced by rattlesnake and water moc- 

 casin venom is, according to Noguchi, the escape of red blood 

 corpuscles from the vessels. Hemorrhages are not restricted to 

 the site of the injection of the venom. Animals killed with snake 

 venom decompose rapidly because of the decrease in bactericidal 

 power of the blood, caused by the venom. 



Toxicity. — According to Barbour the common laboratory stand- 

 ard of toxicity ^ is the minimal lethal dose per pigeon. The poison 

 of sea-snakes which is dangerous to man instantly kills fish. Turtles 

 are almost as susceptible to all venoms as fish. Worms, Insects 

 and Echinoderms are only slightly susceptible to snake venoms. 

 While snakes and frogs quickly succumb to cobra venom, they are 

 relatively insusceptible to the bites of rattlers and moccasins. 

 The digestive juices destroy most snake venoms, but poisons of the 

 cobra, the Old World Vipers, and the Australian black snake are 

 resistant. 



^ Philpott (Proc. Soc. for Exp. Biol, and Med., vol. 26, pp. 522-523, 1929) has 

 shown that the venom of the Texas rattlesnake {Crotalus atrox) in dilutions of 0.00025 

 gm. per cc. had an immediate lethal effect on Paramecium caudatum, Stentor coeruleus 

 and Bursaria truncatella. Action was slow in effect on Volvox spermatosphara and 

 Oxytricha fallax, and was only temporary and slight in Chilomonas Paramecium. 

 Coleps hirtus, Podophyrafixa and Dileptus gigas were unaffected. The minimum lethal 

 dose of Agkistrodon piscivorus (moccasin) for Paramecium caudatum was 0.0000014 

 gm., and for the venom of the fer-de-lance {Bothrops atrox) was 0.0000125 gm. 



