148 PHYTOTOXINS AND ZOOTOXINS 



venom contains no coniplonient, the neurotoxin has first to be supplied 

 with complement by the victim's blood or tissues before it can harm 

 the cells. The venoms are not only toxic for mammalian cells, but 

 also for simple unicellular organisms, including; bacteria; tadpoles 

 are paralj'zed in solutions containing one part of cobra venom per 

 million. ^'^ 



The pronounced hemorrhage-producing property of serums, par- 

 ticularly that of the rattlesnake, was also found to be due to a specific 

 toxin acting on the endothelium of the capillaries and small veins, 

 and not to the changes in the blood itself, as had formerly been thought. 

 This endotheliotoxin, which Flexner and Noguchi call "hemorrhagin," 

 is quite distinct from the other toxic substances, being destroyed at 

 75°, a temperature that leaves the neurotoxin and hemolysin unin- 

 jured. Its endotheliolytic action is show in the glomerular capil- 

 laries, where it causes hemorrhage and hematuria (Pearce).^^ 



Variations in Venoms. — In distribution among the various poi- 

 sonous reptiles these toxins seem also quite distinct from one another, 

 which explains the difference in the effects of bites of snakes of various 

 kinds. Cobra venom contains chiefly neurotoxin, hence the symp- 

 toms of cobra bite are largely of nervous origin, with but little local 

 tissue change. Rattlesnake venom owes its effects chiefly to hemor- 

 rhagin, hence the marked local necrosis and extravasations of the 

 blood, and the generalized hemorrhages; the nervous effects following- 

 viper bite are probably, in part, due to hemorrhages in the nervous 

 tissue. Cobra venom produces great hemolysis and little agglutina- 

 tion. Rattlesnake venom has relatively little agglutinative or hemo- 

 lytic power. Water moccasin and copperhead venoms are more 

 agglutinative than either, and intermediate in heniolytic strength; 

 they cause much local tissue destruction. 



The exact action of cobra venom on various centers and organs has been 

 studied by ElUot.^" It raises blood pressure when in dihition of 1:10.000,000. 

 by contractinfi; vessels and stiinulatint;; the heart; low lethal doses kill by i)ara- 

 lyzing the respiratory center. 



Krait (Bungarus coeridues) venom acts similarly, but loss {xiwerfully, and 

 cannot be neutralized by Calmette's antivenin.'^i 



Sea-snake venoms are by far the most poisonous of all. For Enhi/drina valaLd- 

 dieu the lethal dose for rabbits is O.OOOOti ^ram per kilo body weight. It acts by 

 vagus stimulation and paralysis of respiratory- centers ami oi motor nerve- 

 endings.''-' 



Hussell's viper {Ddhtda Hussrllii) owes its effects chiefly to intravascular dot- 

 ting, according to Laiiil) and llauMa,'"' and conlnins no neurotoxin. It is not 

 neutralized by Calmette's antivenin. 'I'iie dots are ilue to agglutination anil con- 

 tain no fibrin (Flexner). 



••* Bang and Overton, (Biochem. Zeit., 1911(31), 243) state that corpuscles can 

 take up the Mcurotoxin, wliicli is s()lul)le in fats and lipoitls. 



^».)()ur. Mxpcr. iMcd., l'.U)'.> (11), .'):VJ. 



"Lancet, l!»Ot (i), 715. 



"'Elliot, Siljjir, and ('ariiiidi:iel, b:iiicft, I'.KM (ii), IfJ. 



'- Fraser and J<:ili()t, Lancet, 1004 (ii), 141; a'so Rogers, .lour, of Phy.siol., 

 1903 (;}0), iv. 'I'lie al)ove are also given completdv in the Philosophical 'hans- 

 actions of the iloyal Societv, 1904-,'), vol. 1S7. 



'•'.Jour, of I'a'tli. and liact., 1902 (S), 1. 



