BACTERIOLYSIS AND ALLIED PHENOMENA 167 



ferments allied to pepsin or trypsin, which had evidently been 

 formed to digest the ingested food material. He then showed 

 the importance of this process in the absorption of cells, etc., in 

 the tissues of higher animals, and demonstrated that the two 

 processes are altogether similar. Hence his views on the nature 

 of the cytolysins arise easily and naturally. He holds that com- 

 plement, or, as he calls it, cytase, is the digestive secretion of 

 the leucocytes, and that, under ordinary circumstances, it is 

 retained within the leucocytes ; it is only set free when leucocytes 

 are dissolved (phagolysis), either as the result of an injection of a 

 foreign substance or in the process of clotting (this theory, as we 

 shall show, is held by many other authorities). Thus in Pfeiffer's 

 phenomenon the first result of the injection is phagolysis, and the 

 ferments set free in the process immediately attack the cholera 

 vibrios. Metchnikoff has proved clearly that the injection of 

 almost anything into the peritoneal cavity leads to a diminution in 

 the number of leucocytes, but the proof of the existence of 

 phagolysis under these circumstances is less convincing. Cytase, 

 therefore, is a digestive ferment adapted to deal with large masses 

 of food substance rather than with molecules, as Ehrlich supposes, 

 and is normally intracellular, being formed especially for intra- 

 cellular digestion. 



Metchnikoff sees in amboceptor, or fixator, a substance alto- 

 gether analogous to enterokinase, and acting, like it, as an 

 accessory digestive ferment, which has for its object the linking 

 of the more potent ferment to the food to be digested. He 

 regards it also as being formed in the leucocytes, and for this 

 reason (amongst others, which will be enumerated subsequently) : 

 He states that the amount of fixator or amboceptor produced 

 is proportional to the amount of phagocytosis which occurs during 

 the absorption of the antigen. For example, he states that when 

 defibrinated goose blood is injected into the guinea-pig sub- 

 cutaneously there is but little phagocytosis, the blood being 

 dissolved extracellularly, and but little immune body is produced ; 

 but when the injection is made into the peritoneum there is much 

 phagocytosis and much development of antibody. There is cer- 

 tainly a remarkable difference between the various tissues as 

 origins of antibodies, and, as a rule, the subcutaneous and con- 

 nective tissues are most potent in this respect, the peritoneum 

 next, and the circulating blood worst ; but there is no sufficient 

 evidence to show that this depends on the amount of phagocytosis 



