364 BACTERIOLOGY. 



cess, and that often aids in recovery. Ribbert 

 asserts that this surrounding mantle of white 

 blood-corpuscles prevents nutrient material 

 and oxygen from reaching the bacteria, but 

 perhaps also the white blood-corpuscles disin- 

 tegrate, and so become chemically active in 

 the way pointed out by Hankin. In all such 

 cases, there are certain stages in which the 

 parasites in the foci are destroyed without be- 

 ing first taken up by leucocytes. Even Met- 

 schnikoff has lately admitted some such indi- 

 rect participation on the part of the leucocytes. 

 According to R. Pfeiffer, if we inject into the 

 peritoneum of a guinea-pig living cholera bac- 

 teria suspended in bouillon to which some 

 cholera serum has been added, a remarkable 

 alteration of the bacteria makes its appear- 

 ance. They become changed to spherical 

 structures, a transformation which R. Pfeiffer 

 looks upon as a kind of disintegration, and ex- 

 plains as an accompaniment of death. More 

 -accurate experiments by Metschnikoff have, 

 however, resulted in suggesting a somewhat 

 different interpretation. If we proceed accord- 

 ing to Pfeiffer's method, a disintegration of the 

 leucocytes immediately follows the injection, 

 and this disintegration takes place among 

 those uninuclear, polynuclear and eosinophil- 

 ous cells which Metschnikoff looks upon as 



