166 PASTEUR : THE HISTORY OF A MIND 



the corpuscle appear in the midst of all the tissues of the 

 diseased worm, he is confirmed naturally in his idea 

 that the disease is constitutional and that the corpuscle 

 indicates only one of the stages of it, that in which it 

 becomes apparent under the microscope. 



It is a singular thing, that while his spirit marched in 

 these pathways and would not be turned aside, his 

 assistants (preparateurs), to whom he said nothing of 

 what he thought, were persuaded that he was firmly 

 attached to the idea of the corpuscle as a cause. They 

 were astonished that he did not make the crucial experi- 

 ment, and endeavor to give to healthy worms by means 

 of corpuscular food, not the disease with a rapid evolution 

 of which we have just spoken and which did not re- 

 semble the corpuscular disease, but that same disease 

 with its slow evolution and concomitant development of 

 the parasites. Relying on the interpretation he had 

 given to his first experiment, Pasteur did not hasten to 

 begin a second. When that appeared useful to him it 

 was too late. He was in Paris. His associate, M. 

 Peligot, could, nevertheless, give him some worms of a 

 culture which was delayed. With these the inoculation 

 gave results quite other than at Alais; the worms had not, 

 apparently, suffered from the contaminated food, and 

 Pasteur was very much embarrassed until he learned 

 that Gernez had at Valenciennes semi-annual Japanese 

 "graine," that is to say, eggs which would hatch the same 

 year they were laid, and give a second culture of worms. 

 Moreover, these eggs were healthy, the parents not being 

 corpuscular. He, therefore, asked Gernez to do over the 

 experiment which had been made at Alais with worms ob- 

 tained from Peligot, and observe whether the difference 

 in results obtained in Gard and in Paris was not related to 

 the age at which the worms had been subjected to the 

 contagion of the disease. For him it was always the 



