SNAKE-POiSON AND ITS ACTION. 17 



out of the water, and placed on the table before us it 

 gasps for breath and is unable to move. At last 

 respiration ceases altogether and the frog dies. 



Two problems now present themselves for solu- 

 tion, In the first place we have to account for the 

 fact of the snake- poison leaving the lower forms of 

 animal life intact and being fatal to the higher ones. 

 The symptoms we have observed in the frog point 

 unmistakably to an affection of the nervous system as 

 their cause. Now we know that the lower forms 

 which the poison does not affect have no such system, 

 and we are justified to infer that to the absence of 

 this system they owe their immunity. This infer- 

 ence leads us on to a second one equally justifiable, 

 namely, that there is a certain unaccountable attrac- 

 tion between the delicate nerve tissue and the subtle 

 ophidian poison, which renders the latter a specific 

 nerve poison. 



Our second problem is to ascertain the nature of 

 the change in the nerves, to find out, if possible, 

 whether it is merely functional or an actual interfer- 

 ence with the structure of either cells or fibres. With 

 this end in view we once more consult the microscope. 

 We make two preparations, one of nerve fibres and of 

 nerve cells of the poisoned frog, and, under the micro- 

 scope, compare them carefully with an analogous one 

 from the killed healthy frog. The result is purely 

 negative as regards structural change. Both present 

 identical and perfectly normal pictures of apparently 



