1906.] On Opsonins in Relation to Red Blood-cells. 7 



sensibilised in order to excite Phagocytosis. The Serum employed was that of 

 were those of the Guinea-pig. 



of the serum is given in brackets). 



+ + + 

 (1 in 8) 



+ + + 

 (1 in 16) 



+ + + 

 (1 in 32) 



+ + + 

 (1 in 512) 



+ + + 

 (1 in 5) 



+ 

 (1 in 10) 



+ + + 

 (1 in 100) 



i 



1-5* 



+ + + 



(1 in 128) 



+ 

 (1 in 512) 



+ + 

 (1 in 128) 



+ + + 

 (1 in 256) 



(1 in 10) 



+ + + 

 (1 in 100) 



+ + + 

 (1 in 64) 



+ 

 (1 in 256) 



+ + + 

 (1 in 64) 



+ + + 

 (1 in 128) 



(1 in 10) 



+ + 

 (1 in 100) 



+ + + 

 (1 in 32) 



+ 

 (1 in 128) 



+ + + 

 (1 in 32) 



+ + + 

 (1 in 64) 



+ 

 (1 in 10) 



+ + + 

 (1 in 100) 



+ + + 

 (1 in 100) 



+ + + 

 (1 in 16) 



+ 

 (1 in 64) 



+ + + 

 (1 in 16) 



+ + + 

 (1 in 8) 



+ + 

 (1 in 32) 



+ 

 (1 in 16) 



T> 



of Eabbit A in the proportions given. Thus, -5 = -\ 2 means that 32 parts of guinea-pig's blood and 1 part of 



chloride solution and added to the leucocytes. The sign — means that no phagocytosis was observed ; + that 

 red cells ; and + + + that the maximum degree of phagocytosis was reached (2 to 6 per cent., in one 



and are arranged vertically in Table III) as in Experiments 19 to 30. 

 In spite of the variations exhibited by individual experiments fairly definite 

 limiting values are obtainable for most of the sera. Thus in the experiments 

 with Serum A a sharp diminution of sensibilising power is seen when the 

 ratio B/S is less than 1/25, whence it is concluded that 25 parts of serum 

 after deopsination contain only as much opsonin as one part originally did, 

 that is to say, the opsonin has been reduced to 4 per cent, of the amount 

 present at the beginning of the experiment ; with B and C a distinct but less 

 marked change in the sensibilising power of the sera is seen, indicating 

 reduction of opsonin to 2 per cent, and 1 per cent, respectively of the 

 amount originally present ; the opsonin in D is obviously reduced to less than 



