302 SYMBIOGENESIS 



sturm." It is to be called up as a last resource, when every- 

 thing 1 else is in danger of collapse and other defensive forces 

 are already in a state of exhaustion. Similar defensive 

 preparations exist in the polity of an organism, and they are 

 called up to a " storm " (an eliminative crisis, a last symbiotic 

 " elan ") when an enemy threatens the penetralia of communal 

 existence, i.e., when such safeguards as digestive and 

 symbiotic momenta are avoided or put " hors de combat." 



But frequently the outburst of nervous symptoms is so sudden and 

 BO violent that the colic and diarrhoea never appear. Ataxia rapidly 

 supervenes ; the animal staggers as if it were intoxicated ; it becomes 

 paraplegic, drags the hinder part of its body, and does not raise the toes 

 of its fore-paws, thus resembling those animals whose Rolandic convo- 

 lutions have been destroyed. The pupils dilate and the eyes are dulled, 

 while the animal passes urine and ffeces, becomes exhausted and insen- 

 sible, and fails to respond to any reflex stimulations, and assumes a 

 state of complete mind-blindness. Respiration is quickened and 

 dyspnoeic ; the arterial pressure is very low, scarcely 4 to 5 c.m. of 

 mercury. The heart hurries its beats, which are so weak that sometimes 

 they can scarcely be counted. Faecal matter, fluid, diarrhoeic, and 

 blood-stained, pours from the rectum without the animal perceiving it. 

 Breathing soon becomes so harassed that death from asphyxia seems 

 impending. The general condition is serious enough to believe death 

 imminent, but in reality death in less than two hours is extremely rare 

 in the dog. Eesredka has rightly called this sudden alteration of the 

 nervous system anaphylactic shock. 



Here we have a vivid description of a kind of physiological 

 "Land-sturm " in operation. Evidently the whole of the 

 body's symbiotic powers have been called into action. It is a 

 supreme test of, but also a severe tax on, vitality. 



We are also justified now in drawing a parallel between 

 this "anaphylactic" endeavour of the body to eliminate 

 impurities and Mendelian segregation. The symptoms of 

 incubation in anaphylaxis and of " immunisation " with the 

 formation of an "alloy" are comparable to those of 

 Mendelian hybridisation when, say, a diseased strain is crossed 

 with a (more or less) healthy one, as a result of which the 

 formation of a genetic " alloy," i.e., of a damaged F 1 genera- 

 tion ensues. As soon as a second opportunity is provided for 



