1076 PHYSIOLOGY 



cause a very pronounced aggregation of leucocytes which speedily ingest and 

 destroy the micro-organism, whereas if a culture of a more virulent variety 

 of the same microbe be injected, there may be all the signs of inflammation, 

 swelling, and large effusion of fluid, but the tissues may contain very few 

 leucocytes. Under these circumstances the micro-organism rapidly pro- 

 liferates and spreads from the seat of the lesion, giving rise finally to general 

 infection. 



So far we have spoken merely of leucocytes or phagocytes, and have 

 not attempted to distinguish between the parts played by the various types 

 of leucocyte which are found in the blood and connective tissues. In the 

 higher animals there are however very many varieties of leucocytes belong- 

 ing partly to the blood, partly to the connective tissues. The following 

 Table, modified from Adami, enumerates the leucocytes which may be 

 concerned with inflammation in a mammal or man : 



Polymorphonuclear (polynuclear, finely Originating in adult mammals from the 

 granular oxyphile, neutrophile, or bone marrow, and migrating from the 

 amphophile cell). blood into the inflammatory area. 



Eosinophile (coarsely granular oxyphile, 

 macroxycyte). 



Lymphocyte ( ? of two types). Originating from lymphoid tissue and from 



Plasma cell ( ? histogenous). vascular and other endothelia respec- 



Endotheloid leucocyte (mononuclear leuco- tively; present in inflamed area either 



cyte, hyaline cell (in part), ' epithelioid by migration from blood or as result of 



cell ' (in part). local proliferation. 



Connective tissue wandering cell (includ- Originating locally as result of tissue 

 ing clasmatocyte). proliferation. 



The part played by each of these forms is still to a large extent the 

 subject of discussion. There is no doubt that, in all active inflammations, 

 the polymorphonuclear leucocyte is the form which is attracted first and 

 in largest numbers to the seat of injury. It is the characteristic cell from 

 which pus is formed, and is actively phagocytic. It has nothing to do with 

 the regeneration of the destroyed tissue. The eosinophile corpuscle is also 

 present at an early stage around the inflammatory focus, but is never present 

 in numbers at all comparable with those of the polymorphonuclear leucocyte. 

 It is especially abundant in chronic inflammations of certain tissues, such as 

 the skin. According to Kanthack and Hardy, these cells discharge their 

 granules into the surrounding fluid, rendering this fluid toxic for bacteria. 

 Although later observations have failed to confirm these views, no other 

 satisfactory explanation has been given as to the part played by these cells. 

 They are rarely seen to ingest bacteria and therefore cannot be spoken of as 

 phagocytic. The lymphocyte predominates in certain chronic inflammations, 

 especially in those caused by the tubercle bacillus. They do not ingest 

 bacteria. The histogenous wandering cells appear in the inflammatory 

 area at a later period than the polymorphonuclear and eosinophile cells. 

 They are actively phagocytic and are motile. As a rule their phagocytic 

 properties are exerted, not on bacteria, but on other cells and cell debris. 



