248 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
protection against venom and vice versa. The serums of animals naturally 
refractory to the toxins rarely possess antitoxic properties against these toxins. 
They took these facts as in favor of the vital theory. 
A little later C. J. Martin and Cherry ' demonstrated the chemical nature 
of the reaction of venom and antivenin by means of filtration. They pre- 
pared the mixture of venom and antivenin in neutral proportion and allowed 
it to stand for a certain time at 37° C., after which it was filtered through a 
porcelain bougie covered with gelatin. The filtrate was harmless, showing 
that the venom, which should have passed through, had been previously 
destroyed. 
The same authors? also showed that if the neutral mixture of venom and 
antivenin is heated within ro minutes after its mixing the venom is present 
still undestroyed by the antivenin, as the heated mixture is quite lethal. On 
the other hand, the toxic action of venom does not reappear if the mixture is 
heated after 20 minutes or later. These experiments are regarded as con- 
clusive for the chemical nature of the interaction of venom and antivenin, 
which has lately been accepted by Calmette.* 
Stephens and Myers‘ studied the effects of antivenin upon the hemolytic, 
anticoagulating, and toxic properties of cobra venom and showed that the 
neutralization of the first two biological properties of the venom can be effected 
in vitro, looking upon this phenomenon as conclusively chemical. 
REGENERATION OF VENOM AND ANTIVENIN FROM THEIR NEUTRAL 
COMBINATION. 
In 1905 and 1906 Morgenroth made some interesting observations concern- 
ing the interaction of venom and antivenin. He?’ first showed that the neutral 
mixture of cobra venom and antivenin has no power to enter combination 
with lecithin to form haemolytic lecithid, but if a small amount of the normal 
solution of hydrochloric acid is added to such mixture the lecithid is formed. 
Then he ° demonstrated another important phenomenon. If a small amount 
of hydrochloric acid is added to the neutral mixture of venom and antivenin, 
there appears after heating the whole to 100° C. for 30 minutes, in the heated 
fluid at least half of the amount of the neurotoxin originally introduced. The 
failure of total regeneration of the neurotoxin is ascribed by him to the irrep- 
arable modification of the toxin molecule under the action of its antitoxin. 
© In the first instance, hydrochloric acid modified the hemolytic amboceptor 
so as to prevent combination with antitoxin, but still permitting union with 
lecithin. Lecithid, which is formed by subsequent addition of lecithin to the 

1C. J. Martin and Cherry. The nature of the antagonism between toxins and antitoxins. Brit. Med. 
Jour., 1898, II, 1120. 
?C. J. Martin and Cherry. Proc. Roy. Soc., 1898, LXIII, 420. C. J. Martin. Relation of the toxin 
and antitoxin of snake venom. Proc. Roy. Soc., 1899, LXIV, 88. 
%Calmette. Les venins. Paris, 1907, 766. 
* Stephens and Myers. ‘Test-tube reactions between cobra toxin and its antitoxin. Brit. Med. Jour., 
1898, II, 627, and also: The action of cobra poison on the blood, a contribution to the study 
of passive immunity. Jour. of Path. and Bact., 1898, V, 270. 
° Morgenroth. Ueber die Wiedergewinnung von Toxin aus seiner Antitoxinverbindung. Berl. klin. 
Woch., 1905, XLII, 1550. 
° Morgenroth. Weitere Beitrage z. Kenntnis der Schlangengifte und ihrer Antitoxinen. Arbeiten aus 
dem patholog. Institut zu Berlin, 1906, 437. 
