THEORIES OF IMMUNITY. 



precipitates of various kinds. (Ernst and Robey. 

 Trans. Triennial Congress of Physicians and 

 Surgeons, Vol. V., p. 28, 1900.) 



If one favors the idea that phagocytosis is the 

 active factor in disposing of bacteria in the oc- 

 currence of immunity from infection, the phe- 

 nomenon of chemiotaxis must be accounted for, 

 both positive and negative. Metchnikotf does 

 this by the supposition that there exist sub- 

 stances in the immune serum which stimulate the 

 chemiotactic power of the phagocytes toward 

 the invading bacteria. These " stimulines " are 

 supposed by Metchnikotf to" exist along with the 

 " cytases," or else to be these bodies themselves, 

 possessing the stimulating property along with 

 the others that have been ascribed to them. 



Xot enough attention has been paid to the 

 condition of phagocytosis in the phagocyte pro- 

 ducing tissues, after the acute stage has passed 

 away, and on this point there is much to be 

 said. Recently the condition of these tissues 

 has been studied by Roger (Les Maladies Tnfec- 

 tieuses, Paris, 1902, p. 680 et seq.), and Muir 

 (Journal of Pathology, Vol. VII., p. 161, quoted 



88 



