62 The Philippine Journal of Science 1920 
larger amounts of the sera are necessary to produce the same 
result. 
Lastly, the venom of Naja philippinensis hemolyzes equally 
the defibrinated and the washed red blood cells of monkeys. 
PREPARATION OF SERUM 
Following the procedure of Calmette, we used horse for the 
preparation of antivenom serum. According to this investigator 
the fatal dose of cobra venom in twenty-four hours for this 
animal is 0.025 gram. The immunization was begun with a 
dose amounting to one thousandth part of the fatal dose for the 
horse. 
The injections were made subcutaneously at intervals of from 
five to seven days, increasing the dose each time. We used the 
desiccated venom dissolved in salt solution. 
Altogether, the horse was under treatment for a period of 
about ten months, after which time the injections had to be 
discontinued on account of lack of venom due to the death of 
our cobras. 
We started injecting the horse on May 23, 1918, and by 
September 11 it was receiving 0.1 milligram of the venom in 
each injection. On September 12, 10 cubic centimeters of blood 
were withdrawn from the animal for the purpose of determining 
the antitoxic power of the serum. In the experiment four 
guinea pigs weighing from 250 to 450 grams were used. 
Varying quantities of serum were used (0.2 to 1 cubic centi- 
meter) with a double lethal dose. The result was negative in 
that all the guinea pigs died within twenty-four hours. 
By November 20 of the same year, the horse reached the 
dose of 2 centigrams of the venom, and six days later another 
10 cubic centimeters of blood was taken and the serum again 
tried on the guinea pigs. The results were again unsatisfactory, 
since both protected and control animals died, though protected 
guinea pigs survived the controls by three days. 
On January 13, 1919, the horse reached the dose of 12 centi- 
grams of the venom in one injection. The following week blood 
was obtained and the serum tested on guinea pigs as before. 
The results this time were satisfactory. The animal that re- 
ceived 2 cubic centimeters of the antivenom serum survived 
the two control animals. 
On April 7, 1919, the horse reached the highest dose of the 
venom, that is, 0.1555 gram. A few days later, the animal was 
bled 5 liters of blood. The serum thus obtained was tested for 
its preventive neutralizing and curative value. 
