196 Chapter VII 



iu favour of this theory of two phagocytic cytases. He found that, 

 even when specific fixative is added to the extract of microphagic 

 exudations (of rabbit), the seusibilised red corpuscles are not dis- 

 solved. It must then be accepted that microcytase, so active against 

 bacteria, is entirely powerless against animal cells. 



As the microphages seize, though rarely, and digest red blood 

 corpuscles, spermatozoa and other cells of animal origin, it must be 

 admitted that they also contain a small quantity of macrocytase, or 

 that the microcytase, given time, is capable of dissolving these ele- 

 ments. On the other hand, the macrophages, in spite of their marked 

 predilection for animal cells, also ingest and digest certain bacteria. 

 This is due perhaps to the presence of a little microcytase or to the 

 power that the macrocytase has of attacking micro-organisms. These 

 questions are too subtle to be definitely resolved at present. 



The duality of the cytases does not clash with the experiments of 

 Bordet summarised above. We have only to admit that the formed 

 [207] elements, once they are impregnated with specific fixatives, become 

 capable of absorbing not only the cytase which digests them, but also 

 another which, without dissolving them, is simply fixed to them. Here 

 we should have a phenomenon analogous to the fixation by fibrin 

 of diastases, other than trypsin and pepsin, or to the fixation by silk 

 threads of all kinds of soluble ferments. 



It may be accepted, then, that the phagocytes elaborate two 

 cytases : macrocytase, active for animal cells, and microcytase, which 

 digests bacteria. This result up to a certain point has been an- 

 ticipated by Schattenfroh's 1 experiments and foreseen by Max JXeisser 

 (l.c.). 



It has already been noted that the reaction inside the phagocytes 

 is usually feebly or very feebly acid, and only rarely distinctly al- 

 kaline. On the other hand, it is well known that cytases, in serums, 

 act in an alkaline medium. It is certain therefore that these soluble 

 ferments can carry on the process of digestion under varied con- 

 ditions. Hegeler 2 , working in Buchner's laboratory, has studied 

 the influence of the alkalinity and acidity of the medium on the 

 bactericidal action of serum. He comes to the conclusion that the 

 destruction of micro-organisms can take place in a serum to which 

 has been added small quantities of alkali (carbonate of soda) and 

 also in a weakly acid serum (from the addition of small quantities 



* Arch.f. Hyg., Miinchen u. Leipzig, 1899, Bd. xxxv, S. 199. 

 2 Arch.f. Hyg., Miinchen u. Leipzig, 1901, Bd. XL, S. 375. 



