1905.] On the Opsonic Action of the Blood Serum. 381 



the phagocytic power of different bloods is compared ? For many 

 years Metchnikoff has taught that the leucocyte is the dominant factor 

 in phagocytosis. He has also emphasised the training of the leucocyte 

 as the essential thing in immunity. The experiments we have made 

 confirm the results already obtained by Wright and point to the 

 conclusion that the leucocyte is indifferent, the variable in a series 

 of bloods being the serum. In a first series of experiments the leucocytes 

 derived from seven different persons were tested with respect to their 

 phagocytic power, one and the same staphylococcic emulsion and one 

 and the same serum (rabbit's) being used in each case. 



In a second series the sera of the seven individuals whose corpuscles 

 had been used in the above experiment were tested in respect of their 

 opsonic power, one and the same suspension of cocci, and one and the 

 same variety of leucocytes (derived from one of ourselves, "W. B.) being 

 employed throughout. 



Experiment I. Rabbit's serum mixed with emulsion of staphylococci 

 and human leucocytes (from seven persons) in the proportion of 3 : 1 : 3. 

 Phagocytic count obtained by counting the number of cocci in thirty- 

 five polynuclear leucocytes and then calculating the number per 



leucocyte. 



Cocci per 

 leucocyte. 



1. Rabbit's serum + cocci + corpuscles (of W. B., a normal male) = 9 *8 



2. + (ofF.T., ) = 9-3 



3. + + (ofO.G., ) =97 



4. + + (of B.D., ) = 9-6 



5. + + (of C. H., ) = 9 



6. + + (of H. M., an ansemic = 9 '9 



female) 



7. + + (of S. M., male, facial acne) =9 



Experiment II. Various human sera + cocci + one kind of leucocytes 



from a normal male individual. 



Cocci per 

 leucocyte. 



1. Serum of W. B. + cocci + corpuscles of W. B. = 21 '3 



2. F. T. + , + = 20-3 



3. O. G-.+ + 



4. E. D.+ + 



5. C. H.+ + 



6. H.M.+ + 



7. S. M.+ + 



= 21-1 

 = 20 

 = 19'8 

 = 15-5 

 = 14 



The possible objection that the human leucocytes would be injured 

 in contact with rabbit's serum is disposed of by an experiment in 

 which the phagocytic power of one serum, either human or rabbit's, 

 was determined with both human and rabbit's leucocytes. Even in this 

 case the leucocyte is largely an indifferent factor. 



