CELLULAR RESISTANCE 167 



since the work of Mueller and Jochmann, who placed the leucocytes 

 of animals upon plates similar to those used for bacterial cultivation. 

 At incubator temperature, the leucocytes exhibit distinct proteolytic 

 power. Recent studies by Van Calcar would appear to indicate that 

 the organs of the body which secrete digestive ferments have some 

 influence over the ferments existing within the leucocytes. He found, 

 for example, that after the removal of the stomach the leucocytes of 

 the animal were unable to act as peptic digesters. Similarly the 

 removal of the pancreas destroys the ability of the leucocytes to act 

 as tryptic digesters. In summary it is necessary, in order to accom- 

 plish destruction and digestion, to sensitize the organisms and to have 

 present active living leucocytes. Opsonization will not in itself kill or 

 digest the organisms; therefore, the phagocyte must furnish some 

 substance which either completes the action of the opsonin or of itself 

 can kill and digest the organisms. The fact that phagocytosis in all 

 its stages may occur in slight degree independently of opsonin would 

 indicate that the phagocyte is the important element in death and diges- 

 tion of the phagocyted object. Recent work by Bachmann would indicate 

 that the leucocytes of normal and immune animals have a different 

 capacity for protecting against disease. Sixty times more leucocytes 

 from a normal animal were needed to save a guinea-pig against typhoid 

 infection than the number required from an immune animal. In the 

 case of anthrax the leucocytes from immune animals were eighty times 

 more active than those from normal animals. That these studies can 

 be interpreted as indicating a variation in the actual phagocytic power 

 of leucocytes is open to considerable question. 



It is probable that the affinity of the phagocyte and phagocytable 

 object is, in large part if not entirely, a physical chemical phenomenon 

 entered into on the one hand by the cytoplasm of the leucocyte and 

 other cells and, on the other hand, the opsonized organisms or other 

 object. The ingestion, death and digestion are dependent upon the life 

 function of the phagocyte, which is capable of liberating a microbicidal 

 and microbilytic substance capable of combining with the microorgan- 

 ism to bring about its death and destruction. 



OTHER MANIFESTATIONS OF CELLULAR RESISTANCE 



Introduction. rStudies of inflammation and of other cellular activ- 

 ities have made it clear that body cells play an important part in resist- 

 ance to disease that is not entirely explained by the phagocytic capacity 

 of certain of the cells. As has been indicated, cells other than the 

 polymorphonuclear leucocyte and the large mononuclear cell possess 

 the property of phagocytosis, but this is occasional and presumably 

 not of great importance. It seems desirable, however, to discuss the 

 mechanisms of resistance as influenced by properties of the leucocytes 

 other than phagocytosis, by activities of the lymphocytes and by the 

 cells and fluids which play a part in inflammation. 



Bactericidal Extracts of Leucocytes. The destruction of bacteria 

 within the phagocyte so impressed Metchnikoff that he assumed that 



