520 Townsend. — The Correlation of Growth 
In Table VII, in which the shoots were split along one 
side, a retardation in the growth of the shoots was appreciable 
during the first twenty-four hours. This was followed by 
a period of acceleration which continued for five days, at 
the end of which time the growth-rate had again become 
normal. 
When the roots were split, no variation was noticeable in 
either root or leaf during the first period of twenty-four 
Table VII. 
Growth of shoot after the shoot was split on one side. 
Series I. i a.— Shoot split io mm. on one side near the base. 
Helianthus. ( b . — Control. 
Temperature, 2 2° (constant). 
Series. 
Average 
original 
length 
of shoot 
of nine 
seedlings. 
Average 
normal 
rate of 
growth 
of shoot. 
Average 
growth 
of shoot, 
1 st period 
after 
injury. 
Average 
growth 
of shoot, 
2nd period 
_ after 
injury. 
Average 
growth 
of shoot, 
3rd period 
_ after 
inj ury. 
Average 
growth 
of shoot, 
4th period 
after 
injury. 
Average 
total 
growth 
of shoot 
# after 
injury. 
P. 
24 hrs. 
24 hrs. 
48 hrs. 
96 hrs. 
96 hrs. 
264 hrs. 
I. 
a. 
29 mm. 
13 mm. 
15 mm. 
35 mm - 
27 mm. 
19 mm. 
96 mm. 
b. 
30 „ 
12 ,, 
22 „ 
26 ,, 
18 „ 
18 „ 
84 » 
hours ; but after the first twenty-four hours acceleration 
began, and continued for five days in both root and leaf, 
as shown in the last two columns in Table VIII. The 
secondary roots were longer and more numerous in the 
injured than in the uninjured plants 1 . 
A closer study of secondary roots showed that their growth 
was first retarded and afterwards strongly accelerated under 
the influence of injury as seen in Table IX. Experiment b 
shows that the splitting of the roots caused acceleration in the 
growth of shoots as well as of main and secondary roots. 
The number of secondary roots was also increased if too 
much of the main root had not been removed, or if the main 
root was split (3, Table IX). 
1 Pfeffer, Druck und Arbeitsleistung, p. 343, 1893. 
