514 On the Distribution of the Means of Samples 
BO- 
ZO - 
60- 
50- 
Gbaph 4. Curve of 400 Samples of 50. 
The figures below the abscissa represent opsonic indices in terms of the mean of 
the whole series. That is to say, each group unit was translated back into physical 
terms and then divided by the mean number of bacilli per sample for the whole 
count. For instance, in Graph 3, the abscissa "9 was really 5 in statistical units 
corresponding to 39'5 (the origin) + 5x8 bacilli per 25 cells. The mean is 92'04, 
therefore the opsonic index in terms of the mean corresponding to this abscissa 
* The indices as plotted are only given to the nearest first decimal. 
