1904.] Staphylococcus pyogenes by Human Blood, etc. 149 



phagocytic effect which is obtained with the blood of successfully 

 immunised persons is attributable not to any modification induced in 

 the leucocytes, but to an increased opsonic power in the blood fluids. 

 Conclusive evidence of this was obtained by separating, in the case of 

 two bloods of conspicuously different phagocytic power in each case, 

 the blood fluids from the corpuscular elements and then effecting an 

 interchange of the blood fluids. The leucocytes of the successfully 

 immunised patient exhibited under these circumstances the smaller 

 phagocytic action characteristic of the blood of the normal individual 

 who served as a control, while the leucocytes of the normal individual 

 exhibited the increased phagocytic action characteristic of the blood of 

 the successfully immunised patient. 



The witness of the experiment just referred to, and of a previous 

 experiment incorporated in our first paper, is confirmed by similar 

 results obtained in connection with the tubercle bacillus. See 

 pp. 164165. 



Agglutinating Action. Normal human serum does not exert any 

 characteristic agglutinating action upon the staphylococcus. Such 

 agglutination as is obtained is not very sensibly increased under the 

 influence of staphylococcus inoculations. 



(2) Comparison of the Phagocytic Power of the Subjects of Staphylococcus 

 Invasion with the Phagocytic Power of Normal Persons. 



It is clear from what has been said above that the essential change 

 which takes place in human blood, as a result of the inoculation of 

 staphylococcus cultures, is an increase in the phagocytic power, 

 dependent upon an increase of the opsonic elements in the blood. 



Further evidence of the essential importance of the phagocytic and 

 opsonic power in connection with resistance to staphylococcus invasions 

 is obtained by contrasting the phagocytic power of the subjects of 

 staphylococcus invasion with that of normal individuals. 



Our observations on this subject were made in some instances by 

 comparing the phagocytic power of the decalcified blood of the patient 

 with the phagocytic power of the decalcified blood of a normal person. 

 More frequently we employed in our experiments respectively, the 

 patient's serum arid the serum of a normal person in each case in 

 association with the washed corpuscles derived from a normal man. 



The results of our observations are tabulated below : 



M 2 



