704 Journal oj Agricultural Research voi. 52, no. 9, May 1, i936 



where Kis the factor for the number of circular fields per 1-cm^ area, 

 N is the number of circular fields counted, X is the actual mean num- 

 ber of spores per field, 100 is the factor that gives the number of spores 

 per cubic centimeter from 0.01 cc of the suspension, and D is the dilu- 

 tion. The mean number of spores of Bacillus larvae per field counted 

 in 60 fields of stained smears made from the sediments obtained 

 by centrifuging 5-cc quantities of honey contaiuing approximately 

 known numbers of spores have been determined by this method. 



The mean actual spore count per field was determined for a series 

 of samples of honey prepared to contaia approximately 1,000,000, 

 800,000, 500,000, 300,000, and 50,000 spores per cubic centimeter. 

 The mean theoretical spore count per field that should have been 

 recovered was determined by use of the formula 



y_ Number of spores per cubic centimeter 

 32,884 



The actual mean numbers of spores per field were similar in trend 

 to the calculated theoretical means but were from 10.88 to 15.60 per- 

 cent smaller. A statistical analysis of the data to determine the 

 accuracy of the method showed that the calculated probable errors 

 and standard deviations were small. The coefficient of correlation 

 between the actual and the theoretical mean number of spores per 

 field for each sample was found to be 0.9999±0.0001. 



_The relation between the actual mean number of spores per field 

 (F) and the corresponding most probable values that should have been 

 recovered, estimated from the theoretical mean number of spores per 

 field (X), was determiaed by means of the regression equation 

 F=0.8905Z'— 0.1791. These most probable estimated values were 

 found to be in excellent agreement with the actual values obtained, 

 well within the customary limits of ±3 times the standard error of 

 estimate, which was found to be ±0.1298 spore. 



_The most probable theoretical mean number of spores per field 

 (X) was estimated by means of the regression equation X=1.1228F+ 

 0.2034. These values were found to be in excellent agreement with 

 the original calculated values for the theoretical mean, weU within ±3 

 times the standard error of estimate, ±0.1458 spore. 



The statistical analysis of the data therefore indicates that the 

 method used is sufficiently accurate for determining the spore content 

 of unknown samples of honey. For this purpose the following formulas 

 are used: 



X=1.1228F+0.2034±0.4374 



where F=the actual mean number of spores per field counted from 

 60 fields, and 



Number of spores per cubic centimeter=32,884X 



O 



