154 KITAJIMA. 



Alkali has a far-reaching effect upon the venom, for when an equal 

 volume of a one-tenth normal solution of sodium hydroxide' is added, 

 the toxicity falls to one-thirtieth of the original in twenty-four hours, 

 while normal alkali solution completely inhibits the action of the toxin. 

 The venom is also affected by acids. An equal volume of a one-tenth 

 normal solution of sulimuric acid reduces the toxicity to one-fifth and a 

 normal solution to one-tenth of the original strength after twenty-four 

 hours. 



The toxic character of the venom is destroyed by incubation for 

 forty-eight hours at 37° C. with 1 per cent pepsin and 0.2 per cent 

 hydrochloric acid; on the other hand there is a marked resistance to 

 trypsin, which reduces the toxicity only one-half after forty-eight hours. 

 Erepsin has been proved to have no influence over habu venom. 



Snake venom is but little subject to the various changes affecting the 

 diphtheria or tetanus toxins, it retains its toxicity unchanged for two 

 months if it is dissolved in an 0.8 per cent salt solution to which 0.5 

 per cent carbolic acid has been added; however, in the end precipitation 

 gradually sets in with a diminution of the toxicity. A solution in 50 

 per cent glycerin forms a transparent liquid showing no precipitation, 

 and no diminution of toxicity. For this reason I have adopted the 

 solution in 10 per cent glycerin as the standard and this, after dilution, 

 was used in the usual experiments. 



THE ACTION OF HABU VENOM UPON ANIMALS. 



Habu venom is one of the most powerful poisons, affecting a very wide 

 range of animals. Guinea pigs, rabbits, mice, rats, etc., which are com- 

 monly employed in ex2)eriments, die from inoculation of only a small 

 quantity of it. However, its toxicity varies with the season during which 

 it has been collected. The closes lethal after subcutaneous injection are 

 as follows: For the mouse, 0.00005 to 0.0003; guinea pig, 0.0001 to 

 0.001 ; rabbit, 0.001 to 0.006. 



The following figures are obtained according to von Behring's method 

 by expressing the strength of the venom in terms of the body weight of 

 animal killed by one gram of venom : 



1 gram = 30,000 + Ms. to 200,000 + Ms. 



1 gram = 500,000 + G. P. to 2,500,000 + G. P. 



1 gram = 300,000 + P. to 2,000,000 + R. 

 or 



1 gram = the fatal dose for 30,000 to 200,000 grams of mouse. 



1 gram = the fatal dose for 500,000 to 2,500,000 grams of guinea pig. 



1 gram = the fatal dose for 300,000 to 2,000,0.00 grams rabbit. 



The above figures show the minimum lethal doses, killing rabbits and 

 guinea pigs in twenty-four to thirty-six hours, and mice in less than 

 twenty-four hours. If the death of the experimental animal takes more 

 time than these fixed hours, it can hardly be relied upon; moreover, the 



