An Insect Virus 



me, a pain which this time is an intellectual 

 joy. My anticipations were correct. The 

 blood does indeed contain the venomous sub- 

 stance. It causes itching, swelling, a burning 

 sensation, an exudation of serum and, lastly, 

 a shedding of the skin. I learn more than I 

 had hoped to learn. The test is more valuable 

 than that of mere contact with the caterpillar 

 could have been. Instead of treating myself 

 with the small quantity of poison with which 

 the hairs are smeared, I have gone to the 

 source of the irritant substance and I thereby 

 gain an increase of discomfort. 



Very happy in my suffering, which sets me 

 on a safe path, I continue my enquiry by argu- 

 ing thus: the virus in the blood cannot be a 

 living substance, one that takes part in the 

 working of the organism; it is rather, like 

 urea, a form of decay, an offthrow of the vital 

 process, a waste product which is expelled as 

 and when it forms. If this be the case, I 

 ought to find it in the caterpillar's droppings, 

 which are made up of both the digestive and 

 the urinary residues. 



Let us describe the new experiment, which 

 is no less positive than the last. I leave a few 

 pinches of very dry droppings, such as are 

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