THE LEUCOCYTES IN IMMUNITY. 739 



be explained as a simple chemical operation between the two." 

 A similar observation is credited to Wassermann 75 in respect 

 to the bacillus pyocyaneus. Metchnikoff's statement that in 

 cxtravasated blood the leucocytes allow their "plasmane" and 

 a part of their cytases, "which/ 7 he says, "communicate to the 

 serum its hamolytic and 'bactericidal qualities/' to escape, 

 therefore, is not applicable to the living blood-stream. Indeed, 

 he emphatically asserts, as we have seen, that the cytase, the 

 trypsin-containing body, exists under normal conditions solely 

 within the leucocytes. The blood-stream, therefore, must find 

 itself deprived of trypsin: the body which we have seen plays 

 the primary role in the destruction of toxins and other toxic 

 albuminoids. Still, this statement must be qualified. 



We have seen, when the spleen and pancreas were analyzed, 

 that the internal secretion of these organs was poured into the 

 blood-stream about four hours after meals. Between-times its 

 presence could hardly be detected experimentally. Again, post- 

 prandial leucocytosis is a close companion of spleno-pancreatic 

 functions; it also appears some time after a meal. The direct 

 connection between the two is emphasized by the best possible 

 proof: the presence, within the leucocyte, of the spleno-pan- 

 creatic secretion: i.e., trypsin. The marked leucocytosis of 

 neutrophiles only as regards the blood-stream that occurs 

 after acute infections has been sufficiently emphasized. The 

 question to determine is whether this secretion, which is poured 

 into the portal vein by the splenic vein, is entirely absorbed 

 by the leucocytes that pass the splenic veins' orifice when in 

 the portal vein, or whether some is allowed to pass into the 

 blood-stream. 



The experimental evidence adduced in the preceding pages 

 clearly illustrates the baneful results of free trypsin in the 

 presence of the oxidizing substance and fibrinogen. As soon 

 as these three agents are together, their destructive effects can 

 even, we have seen, destroy red blood-corpuscles under appro- 

 priate conditions. The hepatic capillaries receive fresh arterial 

 blood through the hepatic arteries, which arterial blood is 

 mixed with the portal blood in the minute channels of the 



75 Wassermann : Zeitschrift fur Hygiene, Bd. xxii, p. 521, 1896. 



47 



