20 QUATERCENTENARY STUDIES IN PATHOLOGY 



Effect of Temperature. — If the serum of a normal healthy individual 

 be exposed to a temperature of 55 to 60° C. it loses its opsonic power 

 almost entirely ; never, however, completely, for even after heating to 

 60° for one hour there is always a small irreducible minimum left. 



Cocci per 

 leucocyte. 

 Normal serum + Normal corpuscles -f Cocci 18*2 



Normal serum, heated to 60" for 2 mins. + n +11 15 "3 



II + M 13*2 



II 4- M 107 



+ " 5*5 



" + " 5*3 



II + M 37 



+ M 3-5 



II + M 3*3 



M + II 3*1 



II + II 2'9 



Heating to 60° for 60 minutes destroys 83 per cent, of the opsonin 

 contained in the serum, and therefore the opsonin in the serum of normal 

 individuals may be regarded as thermolabile. 



That the irreducible minimum after heating normal serum is still 

 opsonin is shown by an experiment in which a large quantity of cocci 

 are passed through the heated serum and afterwards removed by the 

 centrifuge. 



A quantity of normal serum is heated for 30 minutes in the water- 

 bath at 60° C. A thick emulsion of cocci is added, and the mixture 

 allowed to digest for 15 minutes. The cocci are then removed by 

 centrifugalising for two hours. Result : — 



Cocci per 

 leucocyte. 

 Normal serum - - 15-3 



Normal serum heated to 60° for 30 mins. - - - 2*4 



Serum after treatment as above - - - - - 0*14 



The substance has evidently combined with the cocci, and is thus also 

 opsonin. 



The role of the Leucocyte. — The comparative indifference of the 

 behaviour of the leucocyte in phagocytic phenomena was shown by the 

 early experiments of Wright, and later by Bulloch and Atkin (3°). In a 

 comparison of normal serum and that of a lupus patient, Bulloch and 



(384) 



