Summary 553 



is prevented, the macrophages remaining intact do not allow their [577] 

 macrocytase to escape and the solution of the red corpuscles takes 

 place almost exclusively inside the phagocytes. 



In certain animals the blood serum arrests the movements of their 

 own spermatozoa at once, whilst these remain quite motile in the animal 

 itself. This is due to the fact that the immobilising macrocytase 

 is contained within the macrophages and does not escape from them 

 so long as these cells remain intact. When, in such animals, their 

 own spermatozoa are introduced into the subcutaneous tissue, they 

 remain motile for a long time; when, on the contrary, the sperma- 

 tozoa are injected into the peritoneal cavity, where the leucocytes 

 have not been prepared, phagolysis is produced at once and the 

 spermatozoa become motionless immediately. 



As all these data agree in demonstrating that the uninjured 

 phagocytes retain the cytases — which remain within them, and are 

 not found in the surrounding fluids, — we can readily understand the 

 reason for the differences between the phenomena of immunity and 

 the bactericidal power of the body fluids. The rat's serum is capable 

 of destroying a large number of anthrax bacilli, although these 

 rodents are certainly susceptible to anthrax. The reason for this 

 is that in the serum of the rat the bacilli are destroyed by the 

 microcytase which is set at liberty, whilst in the body of the animal 

 it remains enclosed within the bodies of the living microphages. 

 So long as these cells exhibit a negative chemiotaxis against the 

 anthrax bacillus, the micro-organism remains in the plasma, where 

 it is not interfered with. Thanks to this, multiplication of the bacilli 

 goes on in the body of the animal, the micro-organism killing it after 

 becoming generalised in the blood and in the organs. The suscepti- 

 bility of the leucocytes is, then, the cause of the death of the rats 

 from anthrax, the organism of these rodents being unable to take 

 advantage of its richness in bactericidal microcytase. 



Another paradoxical fact is met with in guinea-pigs immunised 

 against Gamaleia's vibrio {Vibiio metchnikovi). As demonstrated by 

 von Behring and Nissen, the blood serum of these guinea-pigs is 

 very bactericidal for the vibrio in question. A contact of less than 

 an hour is quite sufficient to destroy large numbers of the micro- 

 organisms. Nevertheless, when a small dose of a culture is injected 

 subcutaneously into these hypervaccinated guinea-pigs, the vibrios 

 remain alive for several days, up — indeed, to the moment when they 

 are ingested and destroyed by the leucocytes which come up in large 



