251 PATHOLOGY OF THE BLOOD AND CIRCULATION. 



"It is apparent that the inflammation of vertebrates, in 

 which the defending phagocytes emigrate from the vessels to 

 proceed against offending bodies, is distinguished only quanti- 

 tatively from the analogous phenomena in invertebrates, and 

 must, therefore, be regarded as a reaction of the organism 

 against deleterious agents. We must conclude that the essen- 

 tial factor, the primum movens of inflammation, consists in a 

 phagocytic reaction on the part of the animal organism. All 

 other phenomena are merely accessory, and may be regarded 

 as a means to facilitate the access of phagocytes to the injured 



part The morbid phenomena, properly speaking, 



such as the primary lesion or necrosis, as well as the processes 

 of repair, do not form part of the inflammation, and must not 

 be confounded with it." 



Function and fate of the cellular exudate : The phagocytic 

 power of leukocytes is well recognized, though all varieties 

 do not possess this function to the same degree; it devolving 

 mainly upon the mononuclear and poly nuclear forms, espe- 

 cially the neutrophiles. The lymphocytes are too young and 

 have too little extranuclear protoplasm ; nor are the eosino- 

 philes, the protoplasm of which seems to be undergoing pos- 

 sibly a retrogressive change, ever seen to englobe red blood- 

 cells, micro-organisms, or other foreign bodies. Young con- 

 nective-tissue cells fibroblasts and endothelial cells of 

 bloodvessels and perhaps of lymphatics, especially when 

 rapidly proliferating, possess this function to a marked de- 

 gree. Giant-cells are also occasionally phagocytic. 



In acute inflammations the neutrophiles are the most active 

 phagocytes, while in chronic inflammation the large mono- 

 nuclear leukocytes are the most active. Besides this function 

 as phagocytes at the site of inflammation, the migrated leuko- 

 cytes undoubtedly aid in the restoration of the tissue. Ziegler 

 has long maintained that they develop into connective-tissue 

 cells, and Metschnikoff states that in the wounded tail of a 

 batrachian tadpole, if watched for several days, he has seen 

 the polynuclear cells converted by fusion of their nuclei first 

 into mononuclear cells and then into typical branched con- 

 nective-tissue cells. Also in rabbits all the transitional stages 

 in the conversion of mononuclear leukocytes into epithelioid 

 and giant-cells have been noted. 



