IMMUNITY. 365 



primarily " devouring cells." On the basis 

 of my own observations, I should refer this 

 " phagolysis," this disintegration of the leuco- 

 cytes, to the action of the foreign active 

 proteids contained in the serum, since I have 

 obtained a similar result with enzymes. The 

 peritoneal fluid is by this means converted 

 into a fluid over-rich in active proteid, and poor 

 in phagocytes. Now when the bacteria are 

 transferred from their bouillon into such a 

 differently constituted fluid they attempt, as at 

 all times when some injurious influence threat- 

 ens the species, to withdraw themselves from 

 the danger by passing into the resting-stage, 

 and they consequently form arthrospores. 

 Metschnikoff indeed regards these spherules 

 in this light, and they do indeed appear like 

 true arthrospores (Fig. 196, p. 36), and not 

 like comma bacilli which have undergone de- 

 generation (Fig. 9, p. 19) or granular disin- 

 tegration (Fig. 10, p. 20). To be sure, many 

 of these spherules die, but very many also sur- 

 vive and really preserve the existence of the 

 species, as Metschnikoff proved through ob- 

 taining cultures which yielded an abundant 

 growth, a result which, if we adopted Pfeiffer's 

 view, would not be expected to occur. Later 

 the fluid again becomes normal, these sphe- 

 rules are taken up by leucocytes and only then 



