under the Influence of Injuries . 525 
length, and the normal rate of growth was resumed. It 
was possible to determine approximately the degree of 
injury which had been inflicted upon these plants when they 
were removed from the earth at the end of the experiments. 
When a number of the roots were forced to grow into the 
damp chambers and were then cut away, the results were 
similar to those given in Table XII, though in most cases not 
so marked, since the injury in the latter experiments was not 
so great, and since it was necessary for the influence to act 
through a greater distance. The number of roots cut off 
Table XIII. 
Growth of a leaf after another leaf was removed. 
Series I. ( a, b, and c . — One leaf removed. 
Calla. \ d. — Control. 
Temperature, 17-21 0 . 
Series. | 
Average 
original 
length 
of leaf 
of five 
plants. 
Average 
normal 
rate of 
growth 
of leaves. 
Average 
growth 
of leaves, 
1st period 
after 
injury. 
Average 
growth 
of leaves, 
2nd period 
after 
injury. 
Average 
growth 
of leaves, 
3rd period 
after 
injury. 
Average 
growth 
of leaves, 
4th period 
after 
injury. 
Average 
growth 
of leaves, 
5th period 
after 
injury. 
Average 
total 
growth 
of leaves, 
. after 
injury. 
P. 
24 hrs. 
6 hrs. 
24 hrs. 
24 hrs. 
24 hrs. 
96 hrs. 
174 hrs. 
a. 
245 mm. 
22 mm. 
10 mm. 
32 mm. 
30 mm. 
27 mm. 
68 mm. 
167 mm. 
I. 
b. 
150 » 
*7 „ 
8 „ 
25 „ 
18 „ 
IO „ 
4° » 
IOI ,, 
c. 
211 „ 
20 ,, 
13 » 
37 „ 
45 » 
25 » 
78 „ 
00 
Os 
d. 
00 
18 „ 
4*5 „ 
19 „ 
18 „ 
17 „ 
6 4 >, 
122.5 „ 
was only about one-third as many as in the previous experi- 
ments, and the irritation had to act through nearly twice the 
distance. 
Leaves . — The growth of young leaves of Calla was found 
to be nearly uniform from day to day when the conditions 
were normal and constant. If however the plant was dis- 
turbed by the removal of one of the full-grown vigorous 
leaves, the rate of growth of the young leaves was decidedly 
N n 2 
