Summary 551 



unfavourable conditions of existence to cause them to throw it out 

 from their bodies. The leucocytes, when removed from the animal, [575] 

 undergo a deterioration which soon leads to the deposition around 

 them of filaments of fibrin. 



The cytases must also be grouped with the soluble ferments which 

 are not thrown off by the phagocytes so long as these remain intact. 

 Immediately these cells are injured, however, they allow a part of 

 their cytases to escape. In the blood, withdrawn from the animal, 

 the white corpuscles allow the plasmase to pass into the fluid, where 

 it sets up the coagulation of the fibrin and the formation of a clot. 

 At the same time these cells give up some of their cytases which 

 communicate to the serum its haemolytic and bactericidal properties. 

 This fact is of the highest importance in connection with the question 

 of immunity. The best demonstration of this has been furnished 

 by a comparison of the bactericidal power in the different parts of 

 the body and in the body fluids extracted from the animal. 



When micro-organisms are introduced into those situations in the 

 refractory animal which contain pre-existent leucocytes, the leuco- 

 cytes, under the influence of the shock, undergo serious lesions, 

 accompanied by the throwing out of the cytases. Under these con- 

 ditions the least resistant micro-organisms (such as the cholera vibrio) 

 exhibit undeniable signs of deterioration : they become transformed 

 into granules and may even die in greater or less numbers. When, 

 however, the leucocytes are well protected and withstand the in- 

 jection of the micro-organisms without being profoundly altered, the 

 extracellular destruction of the. micro-organisms does not take place. 

 On the contrary, a very rapid phagocytosis is produced which brings 

 about the death and intracellular digestion of these micro-organisms. 

 Under these conditions vibrios are also transformed into granules 

 and perish, but only within the leucocytes. The phenomena I have 

 just mentioned are brought about in the peritoneal cavity and in 

 the blood vessels of refractory animals, that is to say, in situations 

 rich in leucocytes. 



In the subcutaneous tissue, in the fluids of oedemas and in the 

 anterior chamber of the eye of these same refractory animals, the 

 phenomena are very different. As in these situations there are no 

 pre-existing leucocytes or their number is insignificant, the micro- 

 organisms introduced do not suffer serious injury; they continue to 

 live up to the moment when the leucocytes, having come up as the 

 result of the inflammatory reaction, seize them alive, kill them, 



