262 
H. S. REED 
Growth Rates and Variations of Individual Plants 
The investigation of the characteristics of these plants was carried 
farther by extending it to the individuals instead of studying them in 
groups. The mean quartile position and its standard deviation for each 
plant in the population have been determined as a basis for this study. 
Just as in the case of the larger groups, the mean quartile position of a plant 
gives a measure of its relative size during the entire growth period A plant 
which is constitutionally inferior will have a mean quartile position near I, 
Fig. 3. Curves showing the changes in mean quartile positions for plants finishing in 
the several quartiles. 
plants finishing in first quartile. 
" " " second " 
" " " third 
. " " " fourth " 
and those which have the opposite tendency will have a mean quartile 
position near IV, but by the method of grouping none will be below I and 
none above IV. 
These values have been determined and are presented in classified form 
in table 13, where they can be studied more easily than if given for each 
plant in serial order. The class range has been taken at 0.75 quartile. 
