Laws of Fluctuations 731 



scale with sugar in beets and sugar-cane, with 

 starch in potatoes and in other instances. 

 These figures are also found to follow the same 

 law. 



All qualities which are seen to increase and 

 to decrease may be dealt with ia the same man- 

 ner, if a standard unit for their measure- 

 ment can be fixed. Even the colors of flowers 

 may not escape our inquiry. 



If we now compare the lines, compiled from 

 the most divergent eases, they will be found to 

 exhibit the same features in the main. Ordi- 

 narily the curve is symmetrical, the line sloping 

 down on both sides after the same manner. But 

 it is not at all rare that the inclination is 

 steep on one side and gradual on the other. This 

 is noticeably the case if the observations relate 

 to munbers, the average of which is near zero. 

 Here of course the allowance for variation is on- 

 ly small on one side, while it may increase with- 

 out distinct limits on the alternate slope. So it 

 is for instance with the numbers of ray-florets 

 in the example given on p. 729. Such divergent 

 cases, however, are to be considered as excep- 

 tions to the rule, due to some unknown cause. ' 



Heretofore we have discussed the empirical 

 side of the problem only. For the purpose 

 of experimental study of questions of hered- 

 ity this is ordinarily quite sufiScient. The in- 



