56 PHYSICAL BASIS OF CIVILIZATION 



stings a particular kind of caterpillar in nine definite 

 places, just where the nine principal ganglia of the 

 creature are situated, and then deposits its eggs in 

 the body of the animal, is of this sort. The stinging 

 of the nine ganglia completely paralyzes the cat- 

 erpillar, but does not kill it. The grubs, develop- 

 ing from the eggs deposited in the body, feed on 

 the living flesh of their host, and are thus enabled 

 to survive. These caterpillars live in hot countries. 

 If, instead of being paralyzed, they were stung dead, 

 then their flesh would rapidly putrefy, and the 

 young wasp grubs, instead of being nourished by 

 wholesome food, would be poisoned. That kind of 

 wasp would become extinct. 



Undoubtedly myriads of varieties of wasps died out, 

 because they did not sting in the exact places where 

 the nine ganglia are located. At last one kind was 

 born with nerve structures so precisely adjusted 

 that the nine stings were performed in the exact 

 localities where the nine ganglia are situated. That 

 kind of wasp has survived. Thus nature works out 

 these wonders in infinite time, with infinite variety, 

 through infinite waste, by natural selection. 



Can reason supply any explanation of so wonder- 

 ful an instinct? Indeed, the explanation seems 

 obvious. There must exist a natural attractive 

 affinity (chemical or otherwise) between the sub- 

 stance in the wasp's sting and the substance in the 

 caterpillar's ganglia. 1 This affinity, ordinarily inac- 



1 Although the author believes that in future so-called at- 



