180 PASTEUR : THE HISTORY OF A MIND 



subject had not ceased to haunt his mind. In this 

 year, 1878, there was held in Paris a Congress on 

 silk husbandry, where the subject of flacherie was much 

 discussed, and where Pasteur often found himself moved 

 to speak. From his discourses and conversations we 

 gather the following resume of his ideas on a question 

 to which he never again returned. 



We have described the external signs of the disease 

 and we know also that the mortality may be considerable 

 within a few days, which gives it a distinctly epidemic 

 character. One might call it the cholera or the typhoid 

 of the silkworm. But these are only words; let us 

 endeavor to get at the facts, and at the causes. 



The simplest examination shows that, as in the case 

 oi typhoid or of cholera, it is the digestive organs which 

 are diseased. Sometimes their contents are all foamy, 

 and in full process of fermentation. Sometimes, on the 

 contrary, the fecal substances are in compact masses, 

 hard, and of the same aspect from one end to the other 

 of the intestinal tract, which seems to hava become an 

 inert receptacle. In all cases there is nothing resembling 

 regular, normal digestion, the solid product of which 

 is molded and separated into bits by the muscles of the 

 anus, with the regularity of a machine for making Italian 

 pastes. 



On examining microscopically these normal excre- 

 ments, we find therein debris of leaves but no microbes, 

 or almost none. There is not, so to speak, any place for 

 them in the powerful mechanism of the nutritive system 

 in this animal, which seems made only to eat. It is 

 (juite otherwise in the diseased worms. Their digestive 

 tract is full of microbes; these are bacilli, more or less 

 plump, some of them spore-bearing, and micrococci in 

 pairs and in chains. 



This being the state of affairs, the question arises at 



