314 PHYSIOLOGY: H. S. REED Proc. N. A. S. 
TABLE 2 
Growth of Shoots on Young Pear Trees 
t 
* 
XI 
0i 
X2 
02 
DAVS 
CM. 
CM. 
CM. 
CM. 
CM. 
0 
6 
8 
6 
8 
8.1 
8.1 
7 
5 
10.0 
5.0 
10.7 
5.7 
14 
11 
1 A 
D 
3.6 
15.4 
4.4 
21 
19 
20 
7 
1 
7 
21.3 
2.3 
28 
29 
28 
6 
-0.4 
28.8 
-0.2 
35 
40 
39 
2 
-0 
8 
38.1 
-1.9 
42 
48 
49 
8 
1 
8 
48.5 
0.5 
49 
59 
59 
0 
0 
54.4 
-4.6 
55 
69 
67 
6 
-1 
4 
69.0 
0. 
63 
76 
79 
1 
3 
1 
80.4 
4.4 
70 
86 
88 
2 
2 
2 
88.8 
2.8 
77 
94 
95 
5 
1 
5 
95.6 
1.6 
84 
100 
101 
5 
1 
5 
100.9 
0.9 
91 
102 
105 
5 
3 
5 
104.8 
2.8 
98 
108 
108 
5 
0 
5 
107.6 
-0.4 
105 
110 
110 
5 
0 
5 
109.6 
-0.4 
112 
111 
111 
8 
0 
8 
110.9 
-0.1 
119 
112 
112 
5 
0 
5 
111.9 
-0.1 
126 
113 
113 
0 
0 
112.6 
-0.4 
Root-mean-square deviation 2 . 38 3 . 14 
In a recent paper (Reed, 1920) I showed that the growth of shoots on 
Bartlett pear trees followed the course of an autocatalytic reaction very 
closely, except in the first few weeks of the season. During the early 
part of the growth period the calculated values were larger than those 
observed. Using the observed data I have computed values of K and c 
from the equation 
log (log n4 1 - ) = log K + c log (t - 47.4). 
Plotting the values of this equation (fig. 2) the value of log K (the intercept) 
is -1.75 (#=.0178) and c (the slope) is 1.09. 
When the size of the pear shoots is computed from the equation 
W — = .0178(f - 47. 4) 1 - 09 . 
g 114 - % 
we obtain values agreeing more closely with the observed, as shown by 
table 2, where x = observed mean length of the young shoots at successive 
intervals; %\ — length calculated from 
W = .0178(/-47.4) 1 - 09 . 
^ 114 - % 
$i = deviations of Xi from x; x 2 = length calculated from 
