16 THE FLOATING-MATTER OF THE AIR. 



the beauty of his manipulation finding a fit correlative 

 in the clearness of his thought. 



The following quotation from Pasteur's work clearly 

 shows the relation in which his researches stand to the 

 important question on which he was engaged : 



Place (he says) the most skilful cultivator, even the most 

 expert microscopist, in presence of large cultivations which 

 present the symptoms described in our experiments ; his 

 judgment will necessarily be erroneous if he confines him- 

 self to the knowledge which preceded my researches. The 

 worms will not present to him the slightest spot of pebrine ; 

 the microscope will not reveal the existence of corpuscles ; 

 the mortality of the worms will be null or insignificant; 

 and the cocoons leave nothing to be desired. Our observer 

 would, therefore, conclude without hesitation that the eggs 

 produced will be good for incubation. The truth is, on the 

 contrary, that all the worms of these fine crops have been 

 poisoned ; that from the beginning they carried in them the 

 germ of the malady ; ready to multiply itself beyond measure 

 in the chrysalides and the moths, thence to pass into the 

 eggs and smite with stei'ility the next generation. And 

 what is the first cause of the evil concealed under so deceit- 

 ful an exterior? In our experiments we can, so to speak, 

 touch it with our fingers. It is entirely the effect of a 

 single corpusculous repast; an effect more or less prompt 

 according to the epoch of life of the worm that has eaten 

 the poisoned food. 



Pasteur describes in detail his method of securing 

 healthy eggs. It is nothing less than a mode of restor- 

 ing to France her ancient silk husbandry. The justifi- 

 cation of his wo)k is to be found in the reports 

 which reached him of the application and the suc- 

 cess of his method, while editing his researches for 

 final publication. In both France and Italy his method 

 has been pursued with the most satisfactory results. 

 But it was an up-hill fight which led to this victory. 



