Histoi'ical sketch on Immunity 611 



liave undergone spontaneous cure. This is how Pasteur^ expressed 

 himself on this point : " the muscle which has been much affected [634] 

 has, even after healing and repair, become in some way incapable 

 of supporting the growth of the micro-organism, as if the latter, by 



t previous culture, had eliminated from the muscle some principle 

 at life does not bring back and whose absence prevents the 

 velopment of the small organism. There is no doubt that this 

 planation, to which the plainest facts at the moment lead us, will 

 come general and applicable to all the virulent diseases." 

 This explanation appeared to be a reasonable one to several 

 observers, amongst whom I may cite Chauveau^, the distinguished 

 author of important works on viruses. "In all probability this 

 seductive theory," says Chauveau, "based on one of the most inter- 

 esting of those clear and decisive experiments for which Pasteur is 

 famous, applies to the majority of cases of immunity acquired by 

 protective inoculation." But Chauveau thinks that it does not 

 explain natural immunity, especially that of the Algerian sheep, 

 against anthrax, an example that he had studied on several occasions. 

 When he inoculated into these animals large quantities of anthrax 

 bacilli, not going beyond certain limits, the sheep resisted perfectly ; 

 but injections of enormous doses were nearly always capable of 

 overcoming this natural immunity of the Algerian sheep and of 

 inducing in them a fatal anthrax. Chauveau thinks that this fact 

 is best explained by the presence of an inhibitory substance in the 

 blood plasma, whose action becomes exhausted when distributed 

 over a very large number of bacilli. This opinion was not, however, 

 shared by Pasteur^, who raises the objection that natuml immunity 

 can really be produced and maintained without the presence of this 

 inhibitory substance from the fact that fowls, which exhibit such 

 marked resistance against anthrax, readily contract the disease when 

 the temperature of their bodies is lowered. Under these conditions 

 it is unimaginable that an inhibitory substance has disappeared under 

 the influence of cold. 



The controversy existent from the birth of theories on immunity 

 shows us that from the very commencement the problem was found 

 to be a very complex one, and that to attack it in a satisfactory way 

 we must as far as possible multiply and deepen our study of the 

 phenomena wliich accompany the resistance of the animal against 



1 Compt. rend. Acad. d. sc, Paris, 1880, t. xc, p. 247. 



2 Compt. rend. Acad. d. sc, Paris, 1880, t. xc, p. 1526. 



3 Compt. rend. Acad. d. sc, Paris, 1880, t xcr, p. 536. 



