148 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
reduced to one-tenth of the original; no hemorrhagin was present. Ishizaka 
thought that this was due to the removal of hemorrhagin and that its 
remaining toxicity was due to the presence of the neurotoxin. This fact is 
interesting because of the new way of preparing hemorrhagin-free neurotoxin 
from the Viperide venom. ‘Trypsin destroys the neurotoxin, as well as all 
other active components of this venom. 
For some time controversies existed over the cause of death produced 
rapidly by the injection of daboia venom into the circulation. Brunton, 
Fayrer, and Cunningham considered it to be due to the direct action upon 
the medulla. The symptoms in such a case are restlessness and difficulty in 
preserving equilibrium, gasping, and labored respiration, followed by violent 
convulsions and sudden exitus. Lamb and Hanna! however, demonstrated 
that these symptoms are produced by the formation of extensive intravascular 
thrombosis. A direct application of the venom solution to the medulla or 
the injection of such into the spinal canal of monkey did not produce imme- 
diate symptoms. A few hours afterward the animal appeared dull, lethargic, 
and inclined to lie down. These are symptoms which are usually observed 
in chronic cases when the poison is injected subcutaneously. These symp- 
toms, however, soon passed off and the next day the monkey was all right 
and no further symptoms developed. The above experiment appears suffi- 
cient to exclude the primary neurotoxic nature of this venom in the case of 
rapid death. In the chronic poisoning local and general symptoms develop, 
but do not indicate much effect of this venom upon the nervous system, 
mainly affecting the local tissues and the blood. 
TABLE 6. 
Fresh solution. Heated solution (80° C.). 
0.00005 to 0.0001 gm. | 0.ooor gm. 
0.0004 gm. 0.0004 gm 
0.0004 gm. 0.0004 gm. 
0.0008 gm. 0.001 gm. 
0.001 gm. 0.03 tO 0.05 gm. 
0.001 gm. Did not kill by 0.5 gm. 
Lachesis lanceolatus| 0.005 to 0.006 gm. Ditto. 

Noc determined the toxicity of the venoms of different snakes before and 
after heating them and demonstrated that the venoms which owe their toxicity 
to the thermostabile neurotoxins suffer but trifling reduction in toxicity by 
heating to 80°C. He separated the coagula by centrifugalization and the 
clear fluid was used for the test. Table 6 shows the doses of various venoms 
necessary to kill a mouse within 1.5 to 2 hours. 
Briot and Massol state that the neurotoxins of cobra venom can easily be 
absorbed from the mucous membrane of the rectum, and much more easily 
than by subcutaneous injection. 

1 Lamb and Hanna. Some observations on the poison of Russell’s viper (Daboia russellii). Sci. Mem. 
Off. Med. San. Dept. Gov. Ind., 1903, No. 3. 
2 Jshizaka found that heating this venom to 73° C. for 15 minutes reduced its toxicity to one twenty- 
seventh of the original strength, 
