380 



Dr. W. Bulloch and Mr. E. E. Atkin. [Jan. 10, 



Effect of Heat upon Serum containing Opsonin. Serum ceases to exert an 

 opsonic effect upon bacteria after it has been heated in the water bath 

 at 60 to 65 for 10 to 15'. In most cases the opsonic effect is totally 

 abolished at this temperature, in a few cases, however, some slight 

 effect can be witnessed, but this is mainly, if not entirely, due to traces 

 of serum left attached to the leucocytes where these have been 

 incompletely washed in normal salt solution. 



Experiment. Normal rabbit's serum (three parts), mixed with staphylo- 

 coccus emulsion (one part), and washed human blood corpuscles 

 (three parts). A portion of this was tested, the serum being unheated. 

 Other portions were heated to 60 C. for varying periods. In each 

 case a phagocytic count was made by numbering the cocci in fifty 

 leucocytes and then striking the average per leucocyte. 



Cocci per 

 leucocyte. 



1 (Control). Normal serum + cocci + corpuscles = 14 



2. Serum heated to 60 C. f or 3' + + =0 





6' + 



9' + 



12' + 



15' + 



= 



= 



= 



= 



The opsonin can, however, be destroyed at even lower temperatures 

 if the heat is prolonged. 



Experiment. Here the conditions of the Experiment were the same, 

 with the exception that the serum was heated to 55 and 50 respec- 

 tively instead of at 60 C. 



Cocci per 

 leucocyte. 

 1 (Control). Unheated serum + cocci + leucocytes = 10 '9 



2. Serum heated to 55 C. for 30' + + = '3 



3. 60'+ + =0 

 1. (Control). Unheated serum + cocci + corpuscles = 13 



(1) 



(2) 



2. Serum heated to 50 C. for 



3. 15' + 

 4- 20' + 



5. 25' + 



6. 30' + 



= 3-4 



= 2-4 



= 2 



= 1 



= 1 



Effect of Cold upon Opsonin. Cold exerts 1 ttle effect upon the opsonic 

 power of the serum ; even when immersed in ice water for 24 hours 

 the opsonic value sinks about one-third. At ordinary temperatures 

 the opsonin is remarkably stable, showing practically no diminution 

 for 24 hours. 



Effects of Exposure to Light. In ordinary diffused daylight the opsonic 

 power of the serum remains unaltered for many hours, but when 

 exposed to bright sunlight for 3 hours a serum was seen to become less 

 opsonic in the proportion of 10 : 7. 



Are the opsonins, or are the leucocytes, the variable factors when 



