sept, i, i 9 2i Growth in Branches of Young Pear Trees 
863 
the length of the distal laterals and the number of buds possessed by 
the mother shoots upon which each was produced. The number of 
buds is thought to be of greater biological significance in this case than 
the actual length of the mother shoot. The value of this coefficient for 
the pruned shoots is r= —0.266±0.038, and for the unpruned — 0.196± 
0.088. The negative coefficients are in harmony with the relations 
already observed between mother shoots and their distal laterals.* The 
coefficient expressing the negative correlation between the length of 
the pruned mother shoots and their distal laterals is statistically signifi¬ 
cant and indicates that the more severely the mother shoots were pruned 
k 
1 
§ 
1 
i 
— --—... . 
/ 
1-1 
/ ° 
° / 
A 
- 
/ 
/ 
/ 
' A 
o / 
A / 
/ 
/ * 
/ 
- = 
N. O 
O ON. 
m 
- fv 0V i/U 
M&MLEMOTH OF DISTAL LATERALS'/NCENTtMETERQ 
F ^t~i R T eSSl0 ^ ° f m T length of distal Uterals on mcan number ° f buds per mother shoot. Circles 
niW,I f° b ?7 ed i mC£m k '" etd ° f Iaterals oa Pruned mother shoots; the solid line, the curve of means cal- 
^th^shLl. a.n” K rU , n , 10 ° tS: the triangles, the observed mean length of laterals on unpruned 
mother shoots; and the broken line, the curve of means calculated for laterals on unpruned mother shoots. 
the longer were their distal laterals. For the unpruned mother shoots 
the correlation coefficient is likewise negative, but statistically less reliable 
because of the relatively large probable error accompanying it. Had the 
calculations been based upon a larger population, this coefficient might 
have been closer to that for the other class of shoots. 
The regression of the means in the two cases is shown in figure 6. 
The calculated values were obtained from the formula 
where * is the mean value of the x’s, y of the y’s, and r is the correlation 
coefficient. 
