An Insect Virus 



The swelling diminishes; the redness persists 

 and is still very marked. The effect of the 

 infernal paper lasts a long time. At the end 

 of a month, I still feel an itching, a burning 

 irritation, which is intensified by the warmth 

 of the bed-clothes. At last, a fortnight later, 

 all has disappeared but the redness, of which 

 I shall retain the marks for a long time yet, 

 though it grows gradually fainter and fainter. 

 It will take three months or more to vanish 

 altogether. 



We now have some light on the problem : 

 the Processionary's virus is certainly an off- 

 throw of the organic factory, a waste product 

 of the living edifice. The caterpillar discards 

 it with his excrement. But the material of 

 the droppings has a twofold origin: the 

 greater part represents the digestive residuum ; 

 the rest, in a much smaller proportion, is com- 

 posed of the urinary products. To which of 

 the two does the virus belong? Before going 

 farther, let us permit ourselves a digression 

 which will assist us in our subsequent en- 

 quiries. Let us ask what advantages the Pro- 

 cessionary derives from his urticating product. 



I already hear the answer: 



"It is a means of protection, of defence. 

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