52 NATURAL INHERITANCE. [chap. 



form of M + (±D). If M = 0, or if it is subtracted 

 from every measure, the residues which are the different 

 values of ( ± D) will form a Scheme by themselves. 

 Schemes may therefore be made of Deviations as well as 

 of Measures, and one of the former is seen in the 

 upper part of Fig. 6, page 40. It is merely the upper 

 portion of the corresponding Scheme of Measures, in 

 which the axis of the curve plays the part of the base. 



A strong family likeness runs between the 1 8 different 

 Schemes of Deviations that may be respectively derived 

 from the data in the 18 lines of Table 2. If the slope 

 of the curve in one Scheme is steeper than that of 

 another, we need only to fore-shorten the steeper 

 Scheme, by inclining it away from the line of sight, in 

 order to reduce its apparent steepness and to make it 

 look almost identical with the other. Or, better still, 

 we may select appropriate vertical scales that will enable 

 all the Schemes to be drawn afresh with a uniform slope, 

 and be made strictly comparable. . 



Suppose that we have only two Schemes, A. and B., 

 that we wish to compare. Let L. a , L. 2 be the lengths of 

 the perpendiculars at two specified grades in Scheme a., 

 and K. x K. 2 the lengths of those at the same grades in 

 Scheme b. ; then if every one of the data from which 



Scheme b. was drawn be multiplied by ~ — =^, a 



IV.! IV. 2 



series of transmuted data will be obtained for drawing 

 a new Scheme b'., on such a vertical scale that its 

 general slope between the selected grades shall be the 

 same as in Scheme A. For practical convenience the 



