STUDIES OF 1865 157 



inspired it was replaced by a true idea. For the cor- 

 puscle becoming, as it is really, the sole cause and not 

 simply the effect, or the witness, of the disease, its elimi- 

 nation was all the more profitable, and it is thus that 

 error sometimes leads to the truth. But let us not trust 

 too much to this example. 



However this may be, Pasteur found himself led by 

 his manner of seeing things, to the same method of 

 egg-selection as Osimo, and it is curious to note with 

 what firmness, after 15 days only of sojourn in the places, 

 he indicates to the Agricultural Committee of Alais,^ 

 the 26th of June, 1865, and repeats the 25th of September 

 following, before the Academy, the conditions of a good 

 method of egg-selection. "This means will consist in 

 isolating, at the moment of egg-laying, each couple, 

 male and female. After the mating, the female, set 

 apart, will lay her eggs; then one will open her, as well 

 as the male, in order to search therein for the corpuscles. 

 If they are absent both from male and female, he will 

 number this laying which shall be preserved as eggs 

 absolutely pure, and bred the following year with par- 

 ticular care. There will be eggs diseased in various 

 degrees according to the greater or less abundance of 

 the corpuscles in the male and female individuals which 

 have furnished them."- 



It is, on the whole, a return to the procedure of Osimo, 

 tried and judged worthless by Cantoni, as we have just 

 said. Why had it miscarried when it ought to have 

 succeeded? Perhaps because it had not been tried with 

 confidence, with the necessary faith, perhaps because 

 Cantoni had not sufficiently protected his worms from a 

 new contagion, the effects of which he had confounded 

 with those of heredity. When one follows an idea in 



1 Etudes sur la maladie des vers a soie, t. II. p. 159. 

 ^ Comptes rendus de I'Academie des Sciences, t. LXI, 25 Sept. 1S65. 

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