— 13 - 



From the analyses of the plaice samples, once with regard to length, and once 

 with regard to the number of individuals, or total weight, for each length, we in- 

 variably obtain series of figures progressing from a minimum to a maximum — or 

 several — and falling again to a minimum. Drawn as a graph, these series form 

 curves with one or more highest points. These series or curves, whether representing 



cm. n 16 IÖ 20 22 i» 26 2d 30 32 M 30 38 -iO 'l2 « i6 m 50 52 5^ 56 56 60 6'2 ô'/ 

 de qu. C. Qu ÜC. Vy. 



66 60 70 cirx,. 



Kig. I. Analysis by lengths of all the market-samples which have been measured in the English ports of 

 Grimsby, Lowestoft, Ramsgate and Boston, during the period from October 1905 to the end of September 1908; 



altogether 4,925,698 plaice. Percentage curve. 

 D Mode or greatest density, C Median, A Arithmetic average. Qu, De, Vg quartiles, deciles and vigintiles. 



the actual absolute numbers, or given in relative (percentual) figures, might for our purposes 

 be advantageously made the subject of mathematical discussion, from which we could 

 learn something more about their properties, and thus employ them further in our 

 calculations. With this end in view, we mark off upon such curves a number of cha- 

 racteristic points, the positions of which represent certain important figure-values Such 



