P AT HOGE. VESIS 315 



injected animal leads to a curious result. If a fresh animal, and one 

 previously injected, be given the fatal dose of crepitine, as crepitine 

 only kills in from ten to twenty days, and a first dose never produces 

 immediate effects, the fresh animal is not affected by the injection ; it 

 remains bright, alert, and does not seem to have received the least 

 trace of a toxic substance. But the anaphylactised dog is extremely 

 ill ; it passes bloody motions, and suffers from vomiting, ataxy, and 

 mind-blindness, so much so that it appears to be dying. But fre- 

 quently it recovers, and the next day appears in almost as good con- 

 dition as the other dog. After ten or twelve days the latter becomes 

 cachetic, paralysed, and wretched, and dies ; the anaphylactised and 

 not immunised dog in the meantime gains perfect health. 



This experiment, although apparently paradoxical, is absolutely 

 beyond doubt, and I have repeated it a great number of times. (See 

 Physiological Lab. Rep., 1902, v. p. 514.) 



Thus we see not much more than that (normally) a fatal 

 dose is fatal, which is not exactly "paradoxical," although 

 (abnormally) the anaphylactised dog "frequently" recovers. 

 Where it does "recover," this proves that through being 

 previously given an opportunity of meeting a particular poison, 

 it is able by dint of an adequate incubation period, and in 

 virtue of a sufficient fund of vitality, eventually to cope with 

 even a stronger dose of poison. The second dose now stimulates 

 it to a supreme, and somewhat prepared, symbiotic effort at 

 elimination. But, as good economists, we must not omit to 

 count the cost, nor forget the fact that we have here a patho- 

 genetic process which goes on at the expense of vitality and of 

 survival-capacity. 



What about the dogs that do not "recover"? We must 

 assume that for some reason or other their vitality failed them 

 during the supreme test. 



The non-anaphylactised dog, not being a quick-change 

 artist, being taken by surprise as it were, cannot meet the 

 poison even by a pathogenetic change and dies always a con- 

 venient way out of sudden difficulties. 



The dog which has successfully weathered its anaphylactic 

 shock has also, it appears, got rid of its "immunity" a 

 result on which it is to be congratulated, seeing that 



