1905.] 



On Spontaneous and other Phagocytosis. 



223 



unheated serum was maintained till a 64-fold dilution was arrived at, the 

 opsonic power of two samples of serum which were heated respectively before 

 and after dilution was extinguished when in the former case a 32-fold, and in 

 the latter case a 16-fold dilution was arrived at. 



Comment. — The experiment shows that the opsonin found in heated serum 

 is destroyed by heat when the serum is sufficiently diluted.* 



Explanation of Curve No. 6. — In the experiment here in question we 

 employed a serum derived from a patient with tubercular peritonitis, who had 

 responded to infection in a characteristic manner. 



Concentration in which the serum 

 , was employed. 



S3 

 o 



S, 2 



A 















h 























\ 





k 



V 



-V 











ft 



\3 









afKr 

 heAtin 



if 



< V 



t \ 



& 











rA 



i5 













? 



















+3 



after 

 ne&tin 













Curve 6. 



Dividing it into two portions, we exposed one portion to direct sunlight for 

 a period of six to eight hours, keeping the other portion in the dark in an 

 incubator at 22° C. for the same time. 



We now measured the opsonic power of each portion of serum both in the 

 unheated condition and after exposure to 60° C. for 10 minutes. In the 

 case of the unheated samples we tested in each case not only the undiluted 

 serum but also in each case a series of progressive dilutions. In the case of 

 the samples which were heated we tested only the undiluted sera. 



It will be seen on comparing the phagocytic counts obtained with the 

 insolated and non-insolated sera respectively, that while in the case of the 

 unheated samples the serum which had been exposed to sunlight gave 

 * Further experiments bearing on this question will be found in the Appendix. 



