164 



THE VENOM OF HELODERMA. 



The inhibitory action of rabbit serum was also tested with sodium oleate 

 as an activator. In this experiment, in which guinea-pig corpuscles were used, 

 no inhibitory action was observed. 



We tested not only fresh rabbit sera but also rabbit serum on the second 

 as well as the third day after the blood had been withdrawn. 



Two sera, which on the first day showed no inhibitory action with horse 

 and guinea-pig corpuscles, were markedly inhibitory on the second day. Two 

 other sera, which on the first day showed slight inhibitory power, remained 

 unchanged in their action on the second day. All rabbit sera, whatever their 

 action may have been on the first day, however, showed distinct inhibitory 

 action on the second day. 



On the third day all the sera tested again showed inhibitory action, but 

 while in no case was there an increase, in several cases there appears to have 

 been a decrease of the inhibitory power. The action of such a serum, when 

 tested on three successive days with horse corpuscles, is shown in the following- 

 table. In this experiment the same horse corpuscles as well as fresh horse 

 corpuscles were used, the results being the same with the various corpuscles. 



Mixture of 0.05 mg. lecithin and 0.01 c.c. venom and 2 c.c. of a 5 per cent 

 suspension of horse corpuscles. 



In certain cases the rabbit serum was reheated on the second and third 

 days, and, in order to determine whether such repeated heating of the serum 

 might influence the inhibitory action, we made parallel experiments with serum 

 which was reheated on the second day and a portion of the same serum only 

 heated on the first day. An experiment was also made with serum reheated 

 on the third day and a portion of the same serum which was not reheated. The 

 results in the two parallel series were similar: the reheated serum, and the 

 serum which was not reheated, acted quantitatively and qualitatively in the 

 same manner, so that it is apparent that the reheating had no influence on the 

 inhibitory power of the rabbit serum. 



We may therefore conclude that rabbit serum varies in its inhibitory 

 power ; some sera possess no protective power for horse and guinea-pig corpus- 

 cles, others show this power slightly, but all show some protective power for 

 rabbit corpuscles. After standing 24 hours all rabbit sera develop protective 

 power for horse and guinea-pig as well as rabbit corpuscles, and after standing 

 24 hours longer this power may be diminished or remain unchanged. 



The serum of a rabbit which had been immunized against heloderma 

 venom was added to mixtures of venom, lecithin, and rabbit corpuscles. We 



