378 True , — On the Influence of Sudden Changes of 
made, and no permanent injury is to be seen. After 8 hours 
in water, the normal growth-rate is re-established, and re- 
covery is complete. Indeed, the maximum rate is greater 
than that of the average control-experiment in water. 
Table VI shows the course of the growth of the four Vicia 
Faba roots during and after an exposure of 19 hours in the 
usual solution. 
A comparison with Table V shows that in both cases the 
course of the growth-curve offers no essential difference from 
the preceding. The growth of the average control is here 
again exceeded at the maximum period. 
TABLE VII. 
Period. 
Growth 
per hr. 
Medium. 
Temperature. 
11 ours. 
I 
Min. 
OO 
o-oo mm. 
1 % KN 0 3 
18-7° C. 
30 
+0.30 
Water. 
I 9 , ° » 
3 
OO 
0.26 
>> 
19.8 „ 
2 
30 
0-48 
19.8 „ 
17 
30 
0.70 
l8-6 „ 
27 
OO 
o-68 
20-8 ,, 
20 
00 
o-8i 
>> 
£ 
19.0 „ 
t Estimated average elongation. 
In order to obtain an idea of the minimum period of 
exposure sufficient to produce a retardation of the growth- 
rate following the sudden return to water, experiments were 
made in which the roots were placed in the saltpetre solution 
for a short period. 
A series of roots of Vicia Faba was placed in a 1 per cent, 
solution one hour, then suddenly transferred to water. No 
manifest retardation was observed. When, however, a con- 
centration of 1-5 per cent, was used for the same length of 
time, a decidedly reduced growth-rate was seen to follow the 
transfer to water. Only after several hours was the normal 
growth-rate restored. 
