SNAKE TOXINES. 211 



the air congeals into masses. CALMETTE 1 treated these glands 

 with glycerin, with distilled water, and with a 10 per cent, 

 solution of salt, and invariably obtained extremely poisonous 

 extracts. The toxine acts most energetically when directly 

 injected into the veins, and has less effect when injected sub- 

 cutaneously or into the peritoneum and trachea ; it is absolutely 

 without action when introduced into the intestine. 



The quantity of poisonous saliva secreted was found by 

 CALMETTE (1895) to amount, on the average, to 0-135 grm., 

 corresponding to about 30 to 45 mgrms. of dry substance, 

 provided that from eight to fourteen days were allowed to 

 elapse between the separate bites. On the other hand, after 

 a lapse of two months each bite yielded about 0'22 grm. of 

 saliva. The greatest amount that he was able to extract from 

 the two poison glands of a dead snake was 1'136 grms. = 0'48 

 grm. of dry substance. Similar results were obtained in the 

 investigation of other venomous snakes. 



Thus, there is invariably a considerable increase in the amount 

 excreted, and consequently in the danger from a bite when the 

 snake has not bitten for a considerable time. The bite of 

 hibernating snakes e.g., the European vipers is thus the most 

 dangerous in the spring. 



Preparation of the Poisonous Principle. Snake toxines have 

 not been prepared in even an approximately pure state. The 

 methods of concentration are exactly the same as those employed 

 for all toxines and enzymes. 



The poisonous principle can be extracted by water, salt 

 solutions or glycerin, and purified by repeated precipitation, 

 dialysis, &c. 



MARTIN succeeded in eliminating part of the inactive sub- 

 stances present, by means of fractional coagulation, for on 

 heating a solution of holocephcdus poison in a 0*9 per cent, 

 solution of sodium chloride, a foreign substance separated at 

 85 C., while the true poison remained still active at 90 C. 



CALMETTE 2 subsequently used the following method in the 

 preparation of a stable poison relatively free from proteids : 

 The solution of 1 grm. of cobra poison in 100 c.c. of water was 

 filtered through sterilised filter paper, then heated in a hermeti- 

 cally closed glass tube for thirty minutes at 75 C., and then for 

 twenty-four hours at 80 C., after which it was filtered through 

 paper to remove the separated substances and finally dialysed. 



1 Calmette, "Etude expe"rimentale du venin de Naja tripiidians," Ann. 

 Past., vi., 160, 1892. 

 2 Calmette, " Sur le venin des serpents, &c.," Ann. Past., xii., 214, 1897. 



