BY H. S. HALCRO WARDLAW. 



847 



clearly in the accompanying diagram (Text-fig. 1). The curves 

 are the probability or frequency curves. They show the 



relative closeness of 



grouping 



of the results about their most 



probable values. The abscissae represent the values of the 

 different quantities measured. To facilitate comparison, the 

 values are expressed as percentages of the most probable values, 

 or of the values corresponding to the maximal ordinates. Each 

 ordinate represents the percentages of the total number of results 

 within a certain range of values on either side of it. The range 

 chosen is 5% of the most probable value. 



100 60 60 '10 20 20 40 60 80 

 Percentage Deviation 



Text-fig. 1. 

 Relative variabilities of constituents of cows' milk. Frequency or pro- 

 probability curves showing percentages of total number of results 

 (ordinates) occurring within ±5% of various percentage-differences 

 from most probable values (abscisste). The curves, taken in order 

 from above downwards, represent : percentages of lactose, of solids 

 not fat, and of total solids; conductivity; percentages of ash, of 

 protein, and of fat; total weights of fat, and of milk. 



These frequency curves are the derived curves of the simply 

 obtained ogival curves of Galton. The frequency curves have 

 been drawn by taking, as their ordinates, lengths proportional to 

 the slopes of the corresponding points of the ogive. 



