70 EXPERIMENT STATION. [Jan. 



In plain language, it appears that the few vines bearing an 

 abnormally large number of pods bear also an abnormally large 

 number of peas to the pod. These would certainly be the vines 

 which the pea grower would select in improving his stock 

 toward greater prolificacy. 



If the whole number of vines is studied in one view, without 

 arbitrary division into classes, by the method of compound 

 series, the correlation coefficient is found to be — 0. 017(5, x a 

 number so small as to be entirely negligible. 



While the results involved are of less practical interest, it 

 may be worth while to give the results of other correlation 

 studies with this same material. For instance, we may study 

 the correlation existing between the length of vine and the 

 number of peas per vine. 



Of course we would expect the taller vines to bear the largest 

 number of pods and of peas; and, in fact, the mathematical 

 computation shows a correlation coefficient of — j— . < > < 1 8 2 when 

 it is understood that a coefficient of +1.0 shows the highest 

 correlation that can exist, and indicates two characters abso- 

 lutely dependent on one another, it will be seen that -(-0.668 

 indicates very close relationship between length of vine and 

 number of peas borne. 



If we compute in a similar manner the relation existing be- 

 tween the number of pods per vine and the total number of 

 peas per vine, we find a correlation coefficient of -j-0.897. 3 



These peas will be made the basis of further breeding experi- 

 ments, and a comparison of future generations with the crop of 

 1 1)07 may be expected to develop new points of interest. 



i Standard deviation, pods per vine, 2. (14; peas per pod, 1.14. 

 - Standard deviation, length of vine, 10.5; peas per vine, 10.3. 

 s Standard deviation, pods per vine, 2.64; peas per vine, In.;',. 



