560 IDENTITY OF OPSONINS WITH NORMAL AGGLUTININS, 



in a better way, the reaction between the opsonin and the pro- 

 ducts of the bacterium that has been retarded by heat is complete 

 in at least 20 hours. Contact for 5 hours produced a partial 

 recovery of the reaction. A similar experiment confirmed these 

 results. 



In order to vary the experiment, serum was diluted with 

 normal saline in the proportion of 1 of the former to 4 of the 

 latter, thus making a 20 % solution of serum. It was heated for 

 15 minutes at 50°, 60°, 65° and 70°, then mixed with the suspen- 

 sion of dead bacteria, sealed in capillary tubes and heated at 37* 

 for 24 hours before being treated with the suspension of blood 

 corpuscles. The proportion of dilute serum, bacterial suspension 

 and corpuscles was the usual 3:1:3, and 30 minutes was the 

 time given for phagocytosis to take place at 37°. In enumerating 

 the bacteria ingested, it was evident that the results in some 

 cases could only be approximate, for in certain of the tests the 

 bacteria had agglutinated and many of the phagocytes had 

 gathered round the clumps. Again, polynuclear leucocytes were 

 seen over, under, or against clumps, making it impossible to tell 

 how many cells were within the phagocyte. Furthermore, as in 

 such cases, the cells were not uniformly distributed, every mobile 

 leucocyte would not have the same chance of englobing a staphy- 

 lococcus or even a small clump. When there is no clumping, the 

 numbers of bacteria ingested vary within comparatively narrow 

 limits, but when the microbes are agglutinated the variations are 

 great and there are many phagocytes noted with no bacteria. 

 Since one cannot count the bacteria within the phagocytes which 

 have gathered around a large bacterial clump, even when, as is 

 generally the case, they are gorged, it is only fair to ignore the 

 polymorphonuclear corpuscles when they contain none, one or up 

 to five cells and when they contain over fifty. The proof that 

 such a discrimination is necessary is shown in the following table 

 in the test with the diluted serum heated to 50^. The bacteria 

 were clumped and the readings were — 



Total count (50) = 7 



Omitting numbers under 6 and over 50 as above explained.... (11) = 31 



