48 



and moths contained many corpuscles. From these 

 facts, viewed in the light of his theory that the 

 corpuscles were indeed the cause of the disease, 

 he inferred that the disease had its chief develop- 

 ment in the chrysalid and the moth. If the moths 

 were heavily infected, next year's worms would 

 early show signs of the disease : if the moths were 

 slightly infected, next year's worms would only 

 some of them show signs of the disease, and that 

 late, not early. He compared it to the children of 

 phthisical parents : some of the children will suffer 

 slightly and late, others will suffer heavily and 

 early. 



In February, 1866, he returned from Paris to 

 Alais, with two assistants : they took a house at 

 Pont Gisquet, fitted up a laboratory, and worked 

 incessantly. In June, he writes to his friend Duruy, 

 the Minister of Public Instruction, telling him of 

 the little Cecile's death 



" Here I am, back again, heart and soul, at 

 my work, the one thing which takes me off such 

 a sorrow as mine. ... I shall be in a posi- 

 tion, when I come back, to propose to the Com- 

 mission on Silk-culture a practical way of fighting 

 the evil, and of making it disappear in a few years. 

 . . . My observations show that it develops prin- 

 cipally in the chrysalid, and, above all, in the 

 mature chrysalid, that is, at the moment of the 

 formation of the moth, on the verge of the function 



