Sept, i, 1921 
Growth in Branches of Young Pear Trees 
857 
Tabus IV .—Length of mother shoots plus total length of new wood produced on them 
Mean number of buds on mother shoot. 
Treatment of mother 
shoots. 
Length of mother 
shoot plus total 
new growth. 
Root-mean- 
square devia¬ 
tion from 
mean. 
c. 
Pruned. 
Cm. 
260. o±i4. 6 
293. I ±12. 6 
276. 5± 8. 2 
288. 7 ±11. 6 
285. o±i2. 3 
283. 6± 11. 7 
307. 2 ±16. 1 
381. 7±24. 6 
366. 3 ±23. 9 
39.08 
8. 
.do. 
11.. . . .. 
.do. 
14. 
.do. 
17.. 
.do. 
20...... .. 
26.. 
.do. 
72 .... 
Mean. 
304. 7 ±8- 79 
16.i. 
Unprnned 
178. 6±io. 8 
185. 4± 6. 5 
247- 1 ±14. 9 
30.81; 
24. 
Mean. 
203. 7 ±12. 0 
The coefficient of correlation between the length of the mother shoots 
and the total amount of new growth produced by them is a more concise 
way of expressing the degree of association between the two variables. 
The values of these coefficients were found to be— 
For the unpruned shoots.. i4o±o. 074. 
For the pruned shoots. r =o.004 ±0.041. 
The first coefficient is only twice its probable error and can not be re¬ 
garded as of much significance, and the second coefficient fails to show 
any degree of association whatever. It does not appear, therefore, 
that there is any tendency in these pear trees toward stabilizing the size 
of the system, mother shoot plus new laterals. In other words, there 
is no tendency toward a “restoration of lost parts” through growth. 
The absence of such a tendency to restore lost parts is also emphasized 
by the amount of growth produced on mother shoots which received no 
pruning. Without any stimulus of that sort they produced 58 per cent 
as much new growth as their pruned neighbors. 
relations between the size and the position of laterals on the 
MOTHER SHOOTS 
The laterals growing from the buds on a mother shoot exhibit differ¬ 
ences which are so characteristic as to attract the attention of the most 
casual observer. On the pear, as well as other trees, the longest lateral 
is usually produced at the apex of an upright mother shoot, and each 
successively lower lateral is usually shorter than the one above it. We 
may proceed to a study of the quantitative relations of the laterals in this 
population. 
54131°—21 - 5 
