Vol,. XVI. No. 385. 



THE AGRICULTURAL NEWS. 



29 



A RELATIVE SCORE METHOD OF RECORD- 

 ING COMPARISONS OF PLANT 

 CONDITIONS AND OTHER UN- 

 MEASURED CHARACTERS. 



The following interesting method should be found 

 useful in experiment station work in comparing the 

 general effect of manuring upon individual plants, 

 relative immunity to disease, and such like characters 

 that cannot be actually measured or conveniently des- 

 cribed in words. The account which we publish is 

 taken from the International Review of the Science 

 and Practice of Agriculture (Yter VII, Xo. 2, 

 February 19H)):— 



The lack of means of expressing more or le.'s quantita- 

 tively, relations which are not strictly commensurable, results 

 in the adoption of a method of simple comparison which, 

 though not involving serious error in the case of a limited 

 number, becomes very troublesome and faulty when many 

 plants are to be considered or when non-simultaneous series 

 are to be compared. Two methods are in vogue for avoid- 

 ing these difficulties, viz.: (1) rough classification into 

 excellent, good, fair, poor etc.; (2) arranging the plants in 

 order of merit and assigning numerical values according to 

 an arbitrary scale. 



Both these methods suffer from the inherent difficulty of 

 being dependent for accuracy upon the observer retaining 

 constantly in mind the characters and condition of all plants 

 of the series at the same time. Thi.s is not only difficult but 

 practically impossible when hundreds of plants have to be 

 dealt with. 



This difficulty has been overcome by the use of a method 

 derived from that used by psychologists in the investigation 

 of affections, and which enables the formalisation and partial 

 quantitative expression of compirative judgment formed 

 upon any criterion whatsoever. 



The essence of the method consists in comparing the 

 individuals of the series in pairs, recording the result of each 

 comparison, and the subsecjuent summation of the comparisons 

 of each pair of individuals. The result is therefore a record 

 of individual comparisons of each plant with each other 

 plant, and of the judgment formed in each case. This is 

 reduced to quantitative terms by adding together the sc^ires 

 given to each plant in the course of the comparison. 



The method may be illustrated as follows, in which eight 

 plants are compared as to their general health and condition. 



b 6 



I I 



and the numbers of the first seven in the left-hand margin. 



Plant number 1 is then compared with plant number 2 as to 



their relative condition — all other plants in the series being 



neglected. 



If it is judged that plant number 1 is better, a figure 1 is 

 placed in the square corresponding to plant number 1 on the 

 left and plant number 2 on the top. Proceeding, the com- 

 parison of plant number 1 with plant number 3 leads to 

 a judgment that number 3 is better, and a number 3 is entered 

 in the corresponding square. Similar comparisons of plant 

 number 1 are made with plants numbers 4, 5, 6, 7, and 8, 

 after which a fresh series is begun by comparing plant 

 number 2 with each other plant. In this way a .series of 

 comparisons is made with each plant number. In case no 

 difference is detected a letter 'a' is entered in the square 

 thus counting as no score for either plant. Adding up the 

 score we get the table given below. 



A graph is then constructed by plotting these numbers 

 as ordinates and the numbers of the plants as abscissae. 



Small differences between individual plants can be 

 taken into account by under-scoring or over-scormg the 

 figures entered in each case, and giving each score a valuation 

 ranging from 1 to 3 or 5 according to the accuracy desired. 

 By means of this scheme the writer has been able to 

 obtain comparisons of such diverse things as chemical precipi- 

 tates, degree of Hocculation of clay suspensions, relative 

 ruggedness of mountain ranges, thickness of stand of vege- 

 tation, adhesiveness of wall-paper to different plasters, etc. 



It should be emphasized that this method is nothing more 

 than a .system of faciliating, recording, and formalizing 

 judgment, its accuracy depending upon the correctness of the 

 individual judgments. 



Sixty-four squares are ruled on a sheet of paper, the numbers 

 of the last seven plants being set dnwn in the upper margin, 



Supposed Precipitation of Reducing Sugars 

 by Basic Acetate of Lead. — In a paper in the 



Journal of Agricultut al Science for September last, William 

 A. Davis deals with the question of the supposed precipitation 

 of reducing sugars by basic acetate of lead. As the result 

 of investigations he confirms the findings of Gill, and of Watts 

 and Tempany, that reduiing sugars are not thus precipitated, 

 but that the optical rotary power of the solution is modified; 

 the normal rotation can be restored by the addition of 

 sufficient acetic acid to effect neutralization. 



When, however, a large excess of basic acetate of lead is 

 allowed to act upon laevr.lose for some considerable time, 

 particularly if the solution lie heated, laevulose is transformed 

 probably into glutose, a substance which is nearly optically 

 inactive, and which has a reducing power about one-half 

 that of dextrose. 



