THE CLASSES OJf 



J X i-<J.b 



. of 

 variateg 



Classes.., 



1 



6 



3 



2345 

 FIG. 24. 

 Distribution of frequency in glands of swine. 



, polygon of observed frequency. 



, polygon of theoretical frequency (Type I). 



- - - -, normal frequency polygou. 



10 



