944 VENOMS 
or colleagues, and on the other to the valuable co-operation of the 
Colonial Governments of Indo-China, the French Settlements in 
India, and Martinique, I soon received poisonous snakes and dried 
venom in abundance. 
Fig. 93.—VACCINATING A HORSE AGAINST VENOM AT THE PASTEUR INSTITUTE AT LILLE. 
After this I was not long in pushing the vaccination of a few 
horses until I made them resist, in a single injection, 2 grammes of 
dry cobra-venom, a dose about eighty times lethal; for I was able 
to satisfy myself that about 0°025 gramme of cobra-venom was 
sufficient to kill fresh horses in from twelve to twenty-four hours. 
The immunisation of horses to this very high degree of tolerance 
of venom is not obtained without difficulties; many animals suc- 
