400 
J. ARTHUR HARRIS 
MEAN fl, 
MEAN fps 
PLUS CORRELATIONS 
ZERO BAR 
MINUS CORRELATIONS 
Diagram i. Magnitudes of correlations rpo and rps in 32 series of garden beans. 
The series are arranged in order of magnitude of rpo'. rpo = solid lines and dots; 
rps = broken lines and circles; rpo = solid bar; rps = broken bar. 
lidity of r as a measure of interdependence. It is of interest and import- 
ance biologically, since it shows whether the rate of modification of an 
associated character changes from one end to the other of the range of 
variation of the independent variable. 
The labor involved in testing graphically the agreement of theoreti- 
cal and empirical means for all of the series is prohibitive. Other 
methods of dealing with the problem are, as will be clear in a moment, 
unfavorable. I have, therefore, contented myself with the graphical 
treatment of a few illustrative cases (table II and diagrams 2 and 3). 
In the graphs the means for the full range of variation in number of 
pods per plant has not been shown.^ This arises from the fact that 
^ The observed range of variation in number of pods per plant is indicated in 
the table. Limitations of space preclude the drawing of a scale for the means of 
ovules and seeds for each line, but it is the same for all and may be estimated fairly- 
well by the reader from the end points of the lines as given in the table. 
