1010 RECORD OF CURRENT RESEARCHES RELATING TO 



vaccinated individuals were uninjured, none of them dying; while 

 those not vaccinated succumbed to the poison, both when this was 

 directly introduced into the blood and when it was introduced by the 

 alimentary canal. 



Experience shows that there are individual fowls which are 

 proof from their birth against the poison, being protected by their con- 

 stitution against taking the disease. Therefore it must be assumed 

 in their case that they are devoid of the substance which forms the 

 nutriment of the microbion,just in the same way as the liquor of beer- 

 yeast is absolutely unfitted to nourish the same parasite, while other 

 microscopic organisms thrive very well in this liquid. 



" The explanation to which the facts lead us," says M. Pasteur, 

 " both with regard to the innate resistance which certain individuals 

 manifest, and to the immunity which is induced by repeated vaccina- 

 tions, appears very natural when one remembers that in general every 

 process of cultivation alters the medium in which it takes place : the 

 soil is altered when it comes in contact with ordinary plants ; plants and 

 animals are altered when they meet with their parasites, and our culti- 

 vating liquids are altered when they meet with Mucedinefe, Vibriones, 

 or ferments. These modifications are both betrayed and characterized 

 by the circumstance that fresh growth of the same species in these media 

 is impossible or very difiicult. If we sow fowls' broth with the cholera 

 microbion and filter the liquid after three or four days to remove every 

 trace of it, and sow the filtered liquid afresh with the parasite, this 

 shows itself entirely incapable of undergoing the slightest development. 

 If the liquid is entirely clear after the filtering, it preserves this clear- 

 ness intact. 



Must not the thought occur to us, that by the cultivation of the 

 weakened poison in the fowl, its body is put into the position of the 

 filtered liquid, which cannot support the microbion. The comparison 

 may be followed out further, for if the solution is filtered while the 

 cultivation of the microbion is in full activity — not on the fourth, but 

 on the second day of growth — then the filtered liquid will still be in 

 a condition to grow the microbion afresh, though less energetically 

 than at first. We see therefore that after cultivation of the weakened 

 microbion in the fowl's body we have not been able to exhaust its 

 nutriment in all parts of the body. Thus that which is left behind 

 will allow of a fresh growth, but again to a more limited extent. This 

 is the action of the first vaccination. Subsequent inoculations will 

 gradually remove all the material for the cultivation of the parasite. 

 Through the action of the circulation a moment must come, at which 

 any fresh growth in the fowl remains unfruitful. Then the disease 

 can no longer recur, and the individual is fully vaccinated. It may 

 be wondered that a first growth of the mitigated poison should remain 

 inactive, before the materials for nourishing the microbion are 

 exhausted. But we should not forget that as the microbion is a gas- 

 needing being, it exists by no means under the same conditions in the 

 body of the animal as in an artificial medium for growth. Here there 

 is no obstacle to its increase. In the body, on the contrary, it is 

 incessantly in conflict with the cells of the organs, which are in like 



