116 DR. ELIAS METSCHNIKOPP. 



ducts, but always an accumulation of phagocytes : so that the 

 so-called serous exudation must be regarded as a secondary 

 result of inflammation, the original result being simply an 

 accumulation of phagocytes. 



My whole series of observations, on Vertebrates and Inverte- 

 brates together, is hardly compatible with the current theory, 

 which regards inflammation as primarily due to a morbid condi- 

 tion of the walls of the blood-vessels. I rather believe that the 

 essence of the whole process is a struggle between the phago- 

 cytes and the septic material, whether the latter be a dead or 

 dying cell, or a fungus, or other foreign body. In Invertebrates, 

 where phagocytes are plentiful, the reaction occurs without the 

 participation of the vascular system — which only comes into 

 play among Vertebrates, where the extra-vascular phagocytes 

 are insufficient. The attraction of the white blood-corpuscles is 

 eff'ected, I believe, by the connective-tissue cells and by the cells 

 of the vascular endothelium, which are known to possess a 

 certain amount of mobility. The first eff'ect of irritation is 

 on the connective-tissue cells, which, as has been shown, are not 

 merely passive during inflammation ; and the changes resulting 

 in these may be easily conceived capable of influencing the 

 living cells of the capillary walls, and of inducing such a con- 

 dition as to favour not only the active transit of the white, 

 but the passive diapedesis of the red corpuscles. We may, there- 

 fore, assume the existence of a living chain between the point of 

 irritation and the blood-vessels, which renders possible the 

 intervention of the htemophagocytes even when, as in keratitis, 

 the inflamed spot is far from a blood-vessel. The links of this 

 chain are (1) connective-tissue phagocytes -, (2) endothelial 

 cells of the blood-vessels ; and (3) white blood-corpuscles. 



If the view here advanced were false, and if the theory, 

 which regards the immediate cause of inflammation as a lesion 

 of the capillary walls, were true, then we should expect to find 

 that in cases where the irritant body occurs in the blood 

 itself, the exudation would not be discontinued, but that 

 the white corpuscles would wander away from the irritant. 

 Such a case is aff'orded by those diseases which are due to 



