PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 195 
destroying agents, and it appeared to me advisable to ascertain 
what the amounts and tensions of the gases in the blood of animals 
poisoned by venom were. I have not made any direct quantitative 
observations on the alkalinity of the blood under such circum- 
stances, because the determination of this point presents in this 
case especial difficulties, owing to the fact that the plasma is 
invariably more or less coloured by the presence of hemaglobin 
in solution, so that the range of experimental error is considerable. 
This is not, however, a very serious omission, for the determination 
of the amount of CO, contained in the blood is after all probably 
the best indication we possess of its relative alkalinity. 
Methods of Experimenting. 
The experiments were made upon large dogs, which were pre- 
viously rendered anzsthetic by the subcutaneous injection of 
morphia. On two occasions about 30 cc. of blood was drawn ; 
once previous to, and once at an interval after the injection of 
the venom. For purposes of comparison the first sample was 
employed to determine the amount of the gases in the normal 
blood. As the blood drawn subsequent to the injection of venom 
did not clot, the coagulation of the first sample was prevented by 
drawing the blood into a suitable amount of 1% potassium oxalate 
Solution, which had been previously boiled under diminished 
Pressure. In order that the results from the two samples should 
be strictly comparable, the same course was adopted with the blood 
Withdrawn after the venom injection. 7 
The samples of blood were collected over mercury in the usual 
manner ; the connection between the blood vessel and the receiver 
_ Was filled with the oxalate solution. In most cases the samples 
_ Were taken from the external jugular vein, but occasionally from 
the carotid or femoral artery. They were then transferred from 
| the vessels into which they had been drawn, to the exhausted 
receiver of a mercury pump, containing a small quantity of a 
Solution of oxalic acid. During the exhaustion of the gases from 
_ the blood the receiver of the gas pump was maintained at 37°C. 
