262 
Pearsall.—Studies in Growth. 
The results of the measurements upon these beans are given in 
Table I (Fig. 1) as rates of growth (i.e. increase in volume per two days). 
There are insufficient data for the analysis of these curves, but they show 
the characteristic depression of the rate of growth following (in the case of 
volume measurements) the appearance of secondary roots. The rate of 
root growth then increases once again, when a second factor causes a second 
drop in the growth rate, which subsequently becomes roughly constant. 
The appearance of tertiary roots was not responsible for this second depres¬ 
sion orthe growth rate and consequently some other factor is involved. 
Table I. 
Volume Increase of Bean Roots (in c.c. per two days). 
Series I ( August ). Series II ( September ). 
Days 
1 
2 
3 
4 
5 
6 
7 
8 
2 
29 R 
51 
30 R 
18 R 
R 
27 R 
18S 
10 
4 
16 
74 R 
18 
47 
70 
37 
77 
32 
6 
48 
5 
50 
IOI 
34 
78 
62 
26 S 
8 
59 
9 1 
3i 
138 
3° 
•'«' 
36 
17 
64 
10 
29 
54 
6 
59 
35 
23 
45 
12 
0 
33 
3 
57 
24 
29 
23 
21 
H 
12 
61 
0 
41 
21 
28 
38 
20 
16 
24 
27 
J 9 
8 
!9 
21 
20 
18 
18 
46 
30 
58 
30 
20 
9 
23 
20 
H 
22 
20 
27 
36 
16 
24 
37 
38 
38 
40 
26 
44 
2 
11 
27 
28 
7 
7 
13 
0 
R 
= lateral shoots 
appear. 
S = 
shoot removed. 
(These continuous volumometer readings were obtained in collaboration with Professor J. H. 
Priestley and Miss D. Armstead, to whom the author is very much indebted.) 
A second series of results by the same methods was obtained in 
September, 1920. More detailed notes on the whole plants are available, 
and it is possible to recognize the distinctive features of the rate curve more 
clearly and to correlate them with other growth factors. The results are 
also embodied in Fig. 1. 
The first measurements were taken at the time of the appearance of 
the secondary roots, except in the case of No. 5, where the roots 
developed rather earlier. The growth rate, at first therefore low, rose 
rapidly, and then in all cases again fell to a low level as in the previous 
series. The second drop in root growth was very definitely associated with 
the rapid development of the stem, which grew rapidly after the appearance 
of secondary roots, so that the depression of the root growth rate corre¬ 
sponded with the maximum production of stem and leaves. The demands 
of such a developing shoot on food supply from the cotyledons must be 
equal to or greater than those of the roots, and the rapid development of 
the shoot seems to imply, therefore, a diversion of the food supply from the 
