168 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



center in the medulla oblongata. Myers caUed the first cobralysin and the 

 second cobranervin. The reasons for their independent existence were first 

 furnished by the experiments of Mitchell and Reichert/ who found that 

 the haemolytic principles are precipitated and destroyed by heat before the 

 nerve poison is affected. The second reason is deduced from the fact that 

 the fataUy acting principles are set free in a considerable amount when 

 multiple doses of cobralysin are completely neutralized by antivenin.^ It is 

 only for the minimal lethal dose, or a little over (using guinea-pigs as test 

 animals), that the neutralizations of the two effects run hand in hand. The 

 third reason is that the susceptibility, in vitro, of the red corpuscles of 

 various animals bears no relation to the susceptibility of those animals to 

 subcutaneous inoculation of the venom. 



In this series of study Myers adopted Ehrhch's^ famous fractionated satura- 

 tion method* for diphtheria toxin-antitoxin to analyze the combining prop- 

 erty of cobralysin for anticobralysin. The selection of suitable blood for 

 estimating the haemolytic power of cobra was by no means an easy task, for 

 the corpuscles of the most susceptible animals (namely, guinea-pig and dog) 

 were often haemolyzed by the horse serum alone, rendering the determina- 

 tion of the true action of the venom extremely difficult. The corpuscles of 

 rabbit were more resistant than these two specimens, but much more venom 

 was necessary to obtain enough reaction, and this again made it inconvenient, 

 as the antihsemolytic power of the antivenin he had in hand was so weak 

 that it required i to 2 c.c. to counteract the haemolytic effect produced by 

 o.ooi gm. Myers finally came to use human blood, which, when suspended 

 in I c.c. of isotonic (0.8 per cent) saline solution, was haemolyzed by 0.000003 

 to 0.000005 S^- i^ 2 hours at 1 5° C. It was found that the haemolytic action 

 of 0.00 1 gm. of dried venom was neutrahzed by 1.3 c.c. of the antivenin. 

 Theoretically the addition of one-thirteenth of this amount of the serum 

 should neutrahze ^^ gm., and the second fraction again another ^^gm. and 

 so forth. But, in reality this was found not to be the case. The first frac- 

 tion, instead of neutralizing the theoretical portion of the venom -^ gm., 

 neutralized o.ooi X 0.8, leaving only o.ooi X 0.2 gm. stiU in the fluid 

 unneutrahzed. Speaking of the haemolytic units, o.ooi gm. contained 2,000 

 units, but after the addition of o.i c.c. of the antivenin only 400 units were 

 found to be present in the mixture, whereas it should, theoretically, neutralize 

 only ^ = 153 units by this fraction. The addition of 0.2 c.c. of the anti- 

 venin left 200 units, 0.4 c.c. 125 units, 0.6 c.c. 58.8 units, 0.8 c.c. 20 units, 

 etc. Finally 1.3 c.c. left a dose less than i unit of cobralysin. 



These paradoxical phenomena, first seen by Ehrlich and then by Madsen 

 with other toxins, led Myers to assume that cobralysin consists of a set of 

 substances whose toxic effect can not be observed, but have an antitoxin- 



1 Weir Mitchell and Reichert. Smithsonian Contrib. Knowl., Washington, 1886. 

 * Stephens and Myers. Jour, of Pathol, and Bacteriol., 1898, V, 279. 



3 Ehrlich. Die Wertbestimmung des Diphtherieheilserums. Klin. Jahrb., 1897, VII. 299;andUeber 



die Constitution des Diphtheriegiftes. Deut. med. Wochenschr., 1898, XXXVIII, 597. 



4 Madsen. La constitution du poison diphtherique. Ann. Inst. Pasteur, 1899, XIII, 568. 



