INFECTION AND RESISTANCE 



or leprosy bacilli which are injected into an animal may be at first 

 taken up by polynuclear leukocytes or microphages, by which they 

 may even be carried into the lymph channels and distributed, per- 

 haps to the detriment of the host. But these cells, probably because 

 they lack a lipolytic ferment by means of which the waxes of the 

 acid-fast organisms can be digested, cannot destroy the bacteria, 

 which are then attacked by other cellular elements at the site of their 

 final deposit. 



In many such cases the further resolution of the foreign sub- 

 stance is accomplished by an important type of phagocytosis which 

 is characterized by the formation of the so-called giant cells. These 

 cells are of varying appearance in different conditions and locations. 

 Thus the giant cells which form about foreign bodies, such as the 



small cotton fibers occa- 

 sionally left in wounds, or 

 injected particles of paraf- 

 fin or iron splinters, etc., 

 are quite characteristic and 

 distinct from the giant cells 

 of tuberculous foci, or of 

 rhinoscleroma, glanders, or 

 leprosy. They are all large 

 cells, containing often nu- 

 merous nuclei which form 

 either by the fusion of sev- 

 eral cells, as claimed by 

 Borrell, 18 Hektoen, 19 and 

 others, or by the cleavage 

 of the nuclei alone, with- 

 out coincident divisions of 

 the cytoplasm. 



Although it is, of 

 D r . course, impossible to decide 

 definitely upon purely 

 morphological grounds, the 



researches of Hektoen especially would lead one strongly to favor 

 the former view. It is equally difficult to decide the origin of giant 

 cells, and endothelial, connective tissue, and even leukocytic origin 

 has been claimed for them. Yet in no case has it thus far been possi- 

 ble to actually observe their formation by a method which could posi- 

 tively decide this point. 



In order to gain a clear conception of the participation of phago- 

 cytes in the response of the body to injury or invasion, it will be 

 useful to follow out the process of inflammation as it occurs in the 



18 Borrell. Ann. de I'Inst. Past., 7, 1893. 



19 Hektoen. Jour. Exp. Med., 3, 1898, p. 21. 



FOREIGN BODY OF GIANT CELL. SECTION OF 

 CORNEA AFTER EXPERIMENTAL INJECTION 

 OF PARAFFIN. 



After preparation kindly furnished 

 W. C. Clarke. 



