204 Chapter VII 



agglutination of micro-organisms and to those of natural immunity 

 in general. 



Amongst the properties of humours, there exists one which might 

 play a part in natural immunity against micro-organisms. I mean the 

 [215] power possessed by the blood and certain other fluids of the animal 

 body to neutralise the action of microbial poisons. Perhaps, it may 

 be suggested, the phagocytes are not capable of commencing to do 

 their work except after a previous action of antitoxins. After 

 the neutralisation of the principal means possessed by the micro- 

 organisms to injure the organism, these parasites, having been ren- 

 dered innocuous, might be readily destroyed by the phagocytic cells. 

 We have already had occasion to treat this fundamental question. 

 Thus, we have insisted in the preceding chapters on the absence of 

 any parallelism between immunity against micro-organisms and that 

 against their toxins, taking as our examples anaerobic bacteria (tet- 

 anus bacillus, septic vibrio, bacillus of symptomatic anthrax) in con- 

 nection with which phagocytosis takes place without any help from 

 the antitoxic function. 



We must now pass directly to the examination of the question 

 of antitoxins in the fluids of animals naturally refractory to the 

 micro-organisms and of the ultimate part played by them in this 

 immunity. 



Examples of the presence of antitoxic serum in normal animals 

 are very rare. It might be supposed that animals endowed with 

 natural immunity against micro-organisms and at the same time 

 against their toxins, present an appreciable natural antitoxic power. 

 Let us examine some of the more typical examples. The fowl enjoys 

 a very marked immunity against the tetanus bacillus and its toxin ; 

 its blood and its serum, however, as demonstrated by Vaillard^ 

 exhibit no antitoxic power ; this observation has been confirmed 

 by several other workers. The rat is very refractory to diphtheria ; 

 it resists subcutaneous inoculation of a large quantity of diphtheria 

 bacilli and vigorously withstands diphtheria toxin when injected any- 

 where but into the brain. It has been demonstrated by Kuprianow^ 

 in an investigation carried out under Loeffler's direction, that the 

 blood serum and the emulsion of the organs of the grey rat (Mus 

 decumanus) possess no antitoxic property. This fact has been con- 



^ Compt. rend. Soc. de biol., Paris, 1891, p. 464. 



2 Centralbl./. Bakteriol. u. Parasitenk.^ Jena, 1894, Bd. xvi, S. 415. 



