SNAKE POISON. 3 



cal side of the question, and shown that whereas in some 

 cases the poisons produced by the growth of micro-organ- 

 isms are alkaloidal in nature, in by far the greater number 

 the toxic product is a proteid. The one which is best 

 known, or at least attracted most attention, is the toxalbu- 

 mose contained in Koch's tuberculin. 



The foregoing list is far from complete, but one cannot 

 conclude it without mentioning another class of proteid poi- 

 sons : these are the nucleo-albumins obtainable by suit- 

 able methods from most of the cellular organs of the body. 

 Originally discovered by Wooldridge they were named by 

 him tissue-fibrinogens, because they possess the remarkable 

 power of producing coagulation of the blood within the 

 blood vessels of a living animal. A very small dose will 

 kill a rabbit or a dog, and death is as a rule produced by 

 extensive clotting within the vessels, especially in the veins. 

 Under certain conditions, however, especially in the dog, 

 they produce the opposite result, namely a loss of coagula- 

 bility similar to that produced by peptone. Wooldridge 

 termed this the " negative phase of coagulation ". 



A practical outcome of all this work is the discovery of 

 alexines or protective proteids. These appear to belong to the 

 nucleo-albumin class also. In small doses they confer im- 

 munity on animals to larger doses of similar poisons, and 

 thus the long-hidden secret of the modus operandi of vac- 

 cination and other forms of protective inoculation is at last 

 beginning to be unravelled. 



The limits of the present article would, however, be far 

 exceeded if one were to take up fully all the points hitherto 

 alluded to, and follow them into the various scientific and 

 practical channels into which they have led. I therefore 

 propose in the remainder of this paper to consider in detail 

 one class only of the poisonous proteids : this is one which 

 to the Englishman is of theoretical interest only, but to 

 many thousands of our fellow-creatures it possesses a deep 

 practical importance also : the poisons in question are those 

 which are secreted by snakes. 



In so doing I shall allude chiefly to the most recent 

 work on the subject by Dr. C. J. Martin and Mr. J. M'G. 



