STUDIES OF 1868, 1869, 1870 183 



The discovery of the common character of the germs 

 of flacherie obliges us now to turn back and ask our- 

 selves a question. Why, if this germ is everywhere, 

 does it not develop always and everywhere? This is 

 clearly a general question, like those which precede, 

 and may be asked regarding a multitude of human 

 diseases. The germ of tuberculosis is widely dissemi- 

 nated, we could say to-day. There is not one of 

 us who has not inhaled it. We are exposed to it every 

 day and everywhere ! Why are not all of us tuberculous ? 

 To this question, not yet solved, Pasteur had made, 

 concerning flacherie, a double response. 



This intermittent and localized development of germs 

 universally distributed can take place, he said, whenever 

 external conditions, of which the grower is not always 

 the master, favor the multiplication of the microbes, or 

 enfeeble the digestive power of the worm. The animal 

 is constantly taking in, with the leaves which it eats, 

 germs which would develop in a flask and which do not 

 develop in its digestive tract, arrested as they are by 

 physiological influences. But imagine that they are 

 more numerous for some reason, that the leaf is heated 

 by fermentation before being served to the worm; or 

 again that the number of germs remains the same, but 

 that the worms have been weakened by a stormy period 

 or by a stifling heat when no air is in circulation, or by 

 the fact that the worm-nursery is too warm or poorly 

 ventilated, or by the result of some other accident, and 

 then the germs take advantage of the lowered resistance 

 to multiply and the malady breaks out! 



Finally, to this idea add the fact that the weakening 

 of the digestive tract may be constitutional, organic, 

 may result from the fact that the worms which were the 

 larval ancestors of these eggs, were themselves sick at 

 the time of their pupation or before, with the disease of 



