336 FUNCTIONS OF OTHER ORGANS 



cells, or, as some recent research seems to prove, from the endo- 

 thelium. 



The liver is also an important region with regard to the deposi- 

 tion of bacteria, and their subsequent destruction by phagocytosis 

 or other means, but in this case the main cells concerned are 

 Kupffer's cells. We must regard these two organs and the lungs 

 as being intercalated in the circulation with the object, amongst 

 others, of arresting bacteria and other foreign particles which gain 

 access to the circulation, and affording a region in which phagocytosis 

 can take place at leisure. It has been shown experimentally that 

 animals will resist a much larger dose of bacteria if the injection 

 be made into the portal vein than if it is thrown into one of the 

 peripheral veins. The importance of these organs is also well 

 shown from a study of the fate of inert particles, such as carbon 

 or carmine, when injected into the circulation or peritoneum. In 

 either case they make their way with great rapidity to the organs, 

 especially the liver and spleen, in which they occur in large 

 numbers within two hours of the injection. They are also found 

 within the bone-marrow, lymph glands, tonsils, and lungs, and, 

 whatever the region in which they occur, are mostly contained 

 within the leucocytes or tissue phagocytes. Here also intracellular 

 absorption may take place, though of course it is much slower 

 than is the case with bacteria, and according to Siebel the leuco- 

 cytes, with their load of unabsorbable particles, may leave the body 

 via the lung, tonsils, or lymphoid structures of the small intestine. 



The lung plays a part of great importance, but one not fully 

 understood, in the process of phagocytosis of bacteria which gain 

 access to the circulation. According to some writers, it is the only 

 internal organ in which phagocytosis by polynuclears can be 

 demonstrated, but this is certainly not correct. It is true, how- 

 ever, that soon after the injection of streptococci (Tchistovitch) or 

 cholera vibrios (Levaditi) into a rabbit, polynuclears containing 

 these organisms may be found in large numbers in the wide 

 capillaries of the lung ; this is probably the reason for the sudden 

 fall in the number of the leucocytes in the circulating blood which 

 occurs soon after injection. The reason for this collection in the 

 lungs is very far from clear : the region, remote as it is from 

 lymphoid tissue, would appear an unfavourable battle-ground 

 against the infection ; nor are the later stages of the process fully 

 understood. 



The question of the importance of the bacteriolysins in haemic 



