124 INFLAMMATION. 



tion is a physiological process which we find excessive here, because there 

 are structural alterations in the walls of the vessels which permit a freer 

 exit of the cells, and because there are also present new and active 

 chemical agents which, just as in normal conditions though in exagger- 

 ated fashion, excite and control the movement and direction of the leu- 

 cocytes. The healing processes, complex as they seeni to be, are actually 

 but a rehearsal under unusual and often difficult conditions of cell and 

 tissue formation, which is characteristic of the normal period of develop- 

 ment. Phagocytosis is a factor of the greatest importance in the normal 

 as well as in these abnormal performances of the body cells. 



The degenerative phenomena, among which must be reckoned the 

 formation of fibrin, are, as we have seen, incidental rather than primary 

 factors in inflammation. 



Thus in all the manifold manifestations of abnormal cell performance 

 in inflammation we find no new functions, no new cell capacities. 



We are now brought face to face with the final question : What does 

 inflammation mean ? 



In those phases which involve the repair of wounds and the regener- 

 ation of lost tissues it is not difficult to recognize conservative and bene- 

 ficial processes. But how is it with those phases of inflammation in 

 which the blood-vessels are largely involved and exudates formed 

 serum, fibrin, and pus? Are we to be contented here with a simple sum- 

 mary of the phenomena and with the recognition that these are the results 

 of exaggerated or physiological cell and tissue performances in the face 

 of injury? Or, on the other hand, is there reason for the belief that 

 these abnormal manifestations of cell life in the presence of an unusual 

 and deleterious environment may, after all, be in the main conservative 

 in their nature, and, even as normal cell functions do, tend within the 

 limitations of an emergency to the welfare of the individual ? 



In the hope of gaining some light upon this question let us look a 

 little more closely at the part which the exudates play in exudative inflam- 

 mation ; and first at the leucocytes. 



'It was through the painstaking and brilliant studies of Metschnikoff ' 

 that attention was directed to the importance in this connection of com- 

 parative studies upon the comportment of lower forms of life in response 

 to injury. 



It was found that amoeba, one of the simplest of organisms, when cut 

 in two may undergo complete restitution of the part containing the nu- 

 cleus, provided the latter be uninjured. The remaining portion may 

 live for a time, but ultimately dies. Furthermore, it was found that 

 amoeba and other lowly forms of living beings are capable, by the use of 

 their simple digestive processes, of destroying micro-organisms which are 

 taken into their interior and which might otherwise damage or kill them. 

 Thus it was established that the digestive mechanism may become pro- 

 tective in lowly organized cells. 



Rising in the scale of living beings, it is found that in forms in which 

 1 Metschnikoff, "Comparative Pathology of Inflammation," English translation, 1893. 



