PHAGOCYTOSIS 249 



sequence of phenomena, but it is evident that the division of 

 labour is carried to a high pitch amongst the phagocytes, and 

 that there must be some controlling influence which regulates the 

 appearance of the cell when it is required. 



We must now turn to a discussion of the importance of these 

 facts in connection with immunity as it appeared to the patholo- 

 gists before the discovery of the antibodies. Much of this is 





v^ 



^ 



FIG. 50. FIG. 51. 



V Vifc 







FIG. 52. 



FIGS. 50 TO 52. FROM SCRAPINGS FROM THE LUNGS HALF AN HOUR, Two 

 HOURS, AND TWENTY-FOUR HOURS AFTER THE INJECTION OF POTATO 

 BACILLI INTO A BRONCHUS. (From films lent by Dr. Briscoe.) 



The bacilli, which occurred in large numbers in the alveolar cells half an hour 

 after injection, are not shown. 



mainly of historic importance, but it is of extreme interest, and it 

 is to the controversy which occurred between the cellular and 

 cellulo-humoral schools that we owe much of our knowledge of 

 the processes of inflammation and of the functions of the leuco- 

 cytes. This controversy was carried out with great skill on both 

 sides, and was the means of suggesting numerous experiments 

 of much beauty and ingenuity. To begin with, MetchnikofFs 



