74 



THE BACTERICIDAL SUBSTANCES OF THE BLOOD 



A. Determination of the Strength of the Bacterial Emulsion which 

 Serves as a Basis of the Experiment. The emulsion in question is 

 diluted in the proportion of 1 to 100,000 and 5 c.c. of the resultant 

 dilution distributed over the surface of plates. The number of 

 developing colonies is then counted. The result shows the following: 



Type. 

 Cholera vibrios . 



Typhoid bacilli . 



Average 25.5 organisms 510,000 organisms 



B. Estimation of the Bactericidal Strength of the Serum. Equal 

 quantities ( 1 c.c.) of the undiluted serum and of various dilutions 

 of the original emulsion are mixed and after twenty-four hours' 

 exposure plated out, when the number of developing colonies is 

 counted. 



Type. 

 Cholera 



Typhoid 



1 c.c. of serum thus kills: 



About 410,000 organisms 



About 5100 organisms 



A good idea of the progress of bacteriolysis, and the gradual gain 

 of reproduction over destruction, when the amount of serum was 

 insufficient at the start to kill all the organisms, as also of the differ- 

 ing resistance which different strains of organisms offer to the destruc- 

 tive forces of the serum, may be had from the study of the following 

 table (taken from Trommsdorff). The figures in general represent the 

 variations noted in different tests; those of the a series were obtained 

 with a typhoid strain that had been freshly cultivated from a patient, 

 while the b series has reference to a common laboratory strain. 



