DAILY RHYTHMS IN CERTAIN ROOTS 
the curves are plotted on an equal basis with respect to time after initiation 
of activity. Thus in general, in table 2, maxima occur at 2-6 P.M., 8-12 
P.M., and 4-6 (10) A.M. in the wrinkled-seeded variety; and at 5-7 P.M., 
II P.M.-i A.M., and 5-7 A.M. in the smooth-seeded variety; while 
the minima occur at 10 A.M.-2 P.M., 6-8 P.M., and 2-4 (6) A.M.; and 
1-3 P.M., 9 P.M., and 3-5 A.M. respectively. It will be seen that the 
general character of the curves is the same for both wrinkled-seeded and 
smooth-seeded varieties. Both exhibit three waves of elongation in the 
24-hour period, though the precise time of maxima and minima is usually 
slightly later in the smooth-seeded than in the wrinkled-seeded variety. 
Except in a few cases, observations ceased at the close of the 24-hour 
period. In those few cases in which observations continued longer there 
was no material difference between the two days. The curve continued in 
the same oscillatory or rhythmic manner. The outstanding feature of 
these results is the rhythmic nature of elongation. 
Lupinus albus. Seeds were germinated, and seedlings studied, in the 
Table 3. Lupinus albus. Grouping of Maxima and Minima of Elongation 
plant 
Maxima 
Minima 
68. . . 
3 P.M. 
II P.M. 
7 A.M. 
I P.M. 
9 P.M. 
5 A.M. 
69... 
I P.M. 
I A.M. 
7 A.M. 
II A.M. 
7 P.M. 
5 A.M. 
70. . . 
3 P.M. 
II P.M. 
7 A.M. 
I P.M. 
9 P.M. 
3 A.M. 
71. . . 
3 P.M. 
7 P.M. 
5 A.M. 
I P.M. 
5 P.M. 
3 A.M. 
.72 . . . 
I P.M. 
9 P.M. 
7 A.M. 
I P.M. 
7 P.M. 
5 A.M. 
73 - • • 
3 P.M. 
II P.M. 
7 A.M. 
I P.M. 
5 P.M. 
3 A.M. 
Summary 
Maxima. .... .1-3 P.M. 7 P.M.-i A.M. 5-7 A.M. 
Minima 11 A.M.-i P.M. 5-9 P.M. 3-5 A.M. 
same manner as above described for Pisum. In table 3 the maxima and 
minima of eight representative curves are grouped. A total of 23 different 
individuals was studied. It will be seen that here again three waves of 
elongation occur in the 24-hour period, with maxima at 1-3 P.M., 7 P.M. — ■ 
I A.M., and 5-7 A.M.; and minima at 11 A.M.— i P.M., 5-9 P.M., and 
3-5 A.M. Germination was begun at 9 A.M. 
Curves 70 and 73 illustrate the character of elongation in two of these 
plants. While the corresponding waves (in regard to time of occurrence) 
in the various plants are not all of the same amplitude, the times of their 
maxima and minima are very close, arid the character of the curves is very 
similar, indicating that once these activities are initiated they proceed in 
i^hythmic fashion ; and the time interval of the waves is a more or less nearly 
constant feature. The only earlier work on the root of Lupinus is that of 
Strehl (36). His results are not comparable with those of the present 
paper since his seedlings were exposed to the alternation of day and night, 
and hence any oscillations not induced by this alternation would be likely 
to be entirely concealed by the more prominent daily periodicity. 
