246 Chapter VIII 



These microphages seize the free streptococci that have struggled 

 so victoriously against the macrophages ; this second phagocytic 

 phase is final. The streptococci still remain alive inside the micro- 

 phages for some days, but ultimately are killed and digested by 

 the phagocytes. At a period when, 5 or 6 days after injection, 

 insignificant or isolated traces of streptococci are to be found in 

 the microphages, the exudation when sown in nutritive media still 

 gives abundant cultures. The incidents of this struggle between the 

 streptococcus and the animal organism demonstrate the important 

 part played by the phagocytes. The fact that the macrophages 

 perish and allow the cocci to escape, clearly proves that these cocci 

 have been ingested alive and virulent, and consequently that the 

 fluid of the exudation was incapable of destroying or even of 

 attenuating them. The macrophages, also, were powerless to bring 

 [259] about this result and the intervention of the microphages was 

 necessary to cause the disappearance of the cocci. It is, however, 

 always the phagocytes which ensure the final resistance of the 

 animal. 



In presence of these very precise results obtained from the work 

 of Salimbeni, a work which I followed very closely, the previous 

 researches by Denys and Leclef (l.c.) made under less favourable 

 conditions on vaccinated rabbits are deprived of their importance. 

 These observers wished to get an idea of the difference between the 

 reactions of the animal organism (a) after the injection of streptococci 

 into the pleural cavity of immunised rabbits, and (b) after injection 

 into that of normal susceptible rabbits. They killed the inoculated 

 animals and found a very marked diminution of micro-organisms in 

 the pleuritic exudation of the former. This diminution could not be 

 attributed to a lysis of the streptococci by the body fluids, because 

 there were never any signs of such destruction. Nor could the 

 phagocytosis, very feeble at first, be considered as the cause of the 

 disappearance of a large number of the streptococci. Denys and 

 Leclef put forward a third hypothesis, which attributed this dis- 

 appearance to the rapid resorption by the lymph stream of the 

 injected fluid containing the organisms. Going over the record of 

 their experiments it will be seen that in vaccinated rabbits the 

 quantity of pleuritic exudation was always very much less than in 

 normal rabbits. In presence of this feature there is reason to ask 

 whether, in the case of the streptococci, a large number of these 

 organisms were not fixed, along with the leucocytes, on the walls of 



