GENERAL PROPERTIES AND ACTIONS OF THE VENOM. 89 



tions. All of these pigeons, excepting the one dying after the third injection, 

 had received several injections of 1 mg. of venom, and it was following the in- 

 jection of this amount of venom that they died. The two remaining pigeons 

 received eight injections; the last injection being 1.1 mg. of venom. In view of 

 the poor results obtained with the majority of pigeons we discontinued the 

 experiments. It appeared that pigeons might survive one injection of a lethal 

 dose of venom and die from the effect of a second or third injection of a like 

 quantity. 



In the experiments with rabbits we used in all 16 rabbits. The table 

 on page 88 gives the total amounts injected, the period of time over which 

 the injections extended, and the various doses of venom used. 



It will be seen from the above protocols that the experiments in immu- 

 nizing rabbits were successful in so far as the establishment of an active immu- 

 nity against the venom is concerned. We were, however, unable to push this 

 immunity to as high a degree as it appeared desirable. The rabbits would at 

 times survive the injection of a large dose of venom and eventually die from 

 the injection of an only slightly increased dose. Both the fresh venom and 

 the dry venom were tried; but because of the variation in strength of the 

 fresh venom, the dry venom was used in most cases. 



The injections were given every 5 or 7 days, provided the animal did not 

 show emaciation; if it had lost weight, no injection was given until the original 

 weight had been regained. As a further precaution in the first few injections 

 (in the experiments with rabbits Zl, Z2, Z4, and Z5), the venom was mixed 

 with a 1 per cent solution of calcium hypochlorite, a method of starting the 

 injections for purposes of immunization recommended by Calmette in his work 

 with cobra venom. At first equal quantities of venom solution and calcium- 

 hypochlorite solution were used, but gradually the quantity of hypochlorite 

 solution was diminished and the amount of venom increased. The quantity 

 of venom was increased very slowly until the amount injected was greater than 

 the lethal dose; then the quantities injected were increased somewhat more 

 rapidly. 



Only four of the animals were injected with quantities of venom larger 

 than the usual lethal dose (Rabbits XI, X2, Z4, Z5), and only two of these 

 (XI and Z4) received sufficient quantities to produce any distinct immunity; 

 these two withstood the injection of about eight times the dose lethal for ordi- 

 nary rabbits. 



It is impossible to explain the death of the animals after the injection of an 

 only slightly increased dose of venom or after the injection of a minimal lethal 

 dose of venom. That we are not dealing with a typical anaphylactic reaction 

 is evident from the special experiments in which we tested the anaphylactic 

 power of venom. It appears that the animals' resistance to venom varied from 

 time to time and that the immunity produced was not a definite and stable 

 one. It not rarely happened that abscesses developed at the place of injection, 

 notwithstanding all the precautions taken to insure a sterile procedure. It 

 mav be that after all conditions similar to the Arthus phenomenon of local 



