370 True. — On the Influence of Sudden Changes of 
rate was thereby considerably reduced when compared with 
that made in soil or sawdust 1 . 
As pointed out by Askenasy 2 , the handling of roots inci- 
dental to measurement causes a decided disturbance of the 
growth. By quick and careful handling, it was sought to 
reduce this to a minimum. As all roots used were as nearly 
alike as was practicable to choose them, and as the method of 
handling was as nearly the same in all cases as possible, the 
results may be regarded as comparable. Because of this fact, 
and because of the relative nature of the question under dis- 
cussion, the above errors may the more easily be neglected. 
Experimental. 
Turning now to the experimental part of our subject, it 
seems well at the beginning to notice briefly the growth 
observed under normal conditions. 
In the following experiment the growth of four roots of 
Vicia Faba was observed for a period of approximately 
12 days. The temperature varied between i8° and 20° C. 
The average total length of the roots at the beginning of the 
experiment was about 20 mm. 
Table I shows a summary of the results. 
In the left column, designated £ Period,’ is indicated the 
duration of time in hours and minutes elapsing between 
measurements. In the middle column is shown the rate of 
growth in millimetres per hour , found to prevail during the 
given periods. At the right, the medium used is noted, here 
water during the entire experiment. The first line of the 
table, therefore, shows that during the period of if hours after 
the beginning of the experiment, the average growth -rate 
per hour was 0-50 mm. in water as a medium. 
The very flat curve rises irregularly to a maximum indicating 
a growth-rate of about 1 mm. per hour. By an average tem- 
perature of 19 0 C. it is attained in from 130 to 150 hours after 
1 J. Sachs, Gesammelte Abhandhungen iiber Pflanzenphysiologie, Bd. II, 
p. 796. 
2 Askenasy, loc. cit. 
