2° The Philippine Journal of Science 1915 
of neutral or nearly neutral filtrate (not more than 0.5 per cent normal 
acid) the local reaction is comparatively mild. 
The toxin obtained by this method will usually be such that 
0.0001 (1/10,000) cubic centimeter when injected under the 
skin of a 300-gram guinea pig will prove fatal within five days. 
Toxin of which 0.00005 (1/20,000) cubic centimeter killed the 
guinea pig within five days has frequently been obtained, and 
in one instance the filtrate was such that 0.00002 (1/50,000) 
cubic centimeter killed a 300-gram guinea pig within five days. 
Recently good toxin has been obtained by the method de- 
scribed by Ivan Hall. His method is as follows: 
1:7 ivMiedastilled watery.) ..2 5 seen eee at i aeviney i 1,000 c.c. 
IN@Clln (CRP Sie wa ee Ree et ee ee 5 gr. 
Peptony (Wachee ee a ee eee 10 gr. 
Beef Extract (Armour’s soluble beef) ...........-..--. 5 gr. 
Dextrose \(GCommerciall) Wa ees ee ce ee eee 10 gr. 
MgCoO; (finely powdered commercial) ...........-........------------- 5 er: 
2. Determine gross weight. 
8. Dissolve by boiling and stirring. 
4, Restore the original weight with distilled water. 
5. Cool overnight to precipitate the phosphates. 
6. Filter through coarse paper. Reaction should now be found 
faintly alkaline to phenolphthalein. 
Add 2 gm. MgCO; and mix thoroughly. 
Pour into Florence flasks to shoulder. 
9. Cover to a depth of 2 em. with hydrocarbon oil (Langley & 
Michaels, San Francisco). 
10. Sterilize in the Arnold 3 successive days, 40 minutes each time. 
On the following pages are reported the methods of immu- 
nization and the results obtained from 8 horses at the Bureau 
of Science, Manila, P. I. 
pons 
HORSE 1 
Horse 1 in this series was given about 1,000 units of tetanus 
antitoxin* on June 4, 1911, and another dose of about 1,000 
units on June 23, 1911. Tetanus toxin was given at short 
intervals, and the quantity was rapidly increased. 
During the first three months 26 injections were given, and 
at the last injection the horse received 600 cubic centimeters of 
toxic filtrate. It became evident that the injections were being 
pushed too rapidly, so the horse was allowed to recuperate. On 
*Univ. Calif. Publ. Path. (1918), 2, 98. 
“Unit of tetanus antitoxin refers to the standard unit of the United 
States of America. The quantity of antitetanic serum which neutralizes 
the test dose (approximately 100 minimal lethal doses) contains 0.01 of a 
unit of antitoxin, hence a unit may be said to neutralize 1,000 minimal 
lethal doses of toxin tested on guinea pigs weighing 350 grams each, 
