390 
RAY C. FRIESNER 
Allium Cepa. Roots from both germinating seeds and bulbs were used. 
The bulbs were uniform and of a medium-sized white variety, and the seed 
of the Yellow Danvers (D. M. Ferry & Co.) variety. 
Roots from Bulbs. In table 4 are grouped the times of maxima and 
minima of the elongation of the roots of seven different plants. These are 
chosen to represent the various types of curves, and consequently show some- 
what less approach to uniformity than when all curves are considered. 
Curves 272 and 296 show three waves of elongation in the 24-hour period. 
The maxima come at 7-9 A.M., 7 P.M., and i A.M.; and the minima at 
1-3 P.M., II P.M., and 5 A.M. This type of curve is exhibited by about 
Table 4. Allium Cepa (bulb). Grouping of Maxima and Minima of Elongation 
Plant 
Maxima 
Minima 
263... . 
261... . 
264. . . . 
254... . 
271. . . . 
272. . . . 
296. . . . 
II A.M. I A.M. 
7 A.M. I P.M. 9 P.M. I A.M. 
II A.M. 5 P.M. 9 P.M. 5 A.M. 
9 A.M. 9 P.M. I A.M. 
II A.M. 7 P.M. 3 A.M. 
9 A.M. 7 P.M. I A.M. 
7 A.M. 7 P.M. I A.M. 
9 P.M. 3 A.M. 
9 A.M. 5 P.M. II P.M. 5 A.M. 
3 P.M. 7 P.M. II P.M. 7 A.M. 
3 P.M. II P.M. 7 A.M. 
5 P.M. II P.M. 5 A.M. 
3 P.M. II P.M. 5 A.M. 
I P.M. II P.M. 5 A.M. 
Summary 
Maxima 7-1 1 A.M. 7-9 P.M. 1-3 (5) A.M. 
Minima 1-5 P.M. 9-11 P.M. 3-7 A.M. 
75 percent of the plants. Comparison with Kellicott's (14) curves shows 
only slight differences in the exact time of occurrence of maxima and minima. 
A second type of behavior is illustrated in curves 261 and 264 where four 
waves are found in the 24-hour period. Three of these waves correspond 
closely, in regard to time, to those of the other plants which show three 
waves. A third type of curve is that shown by plant 263 where but two 
waves are found in the 24-hour period. Kellicott (14, page 545, fig. 7, 
curve II) shows a similar curve with but two waves. Two plants out of a 
total of 50 showed this type of curve. 
Roots from Seeds. Curves for elongation of -roots from seedlings differ 
from those from bulbs mainly in that they are about equally divided between 
three- and four-wave types. In curves 275 and 288 three waves are shown, 
while curves 273, 274, and 276 exhibit four waves. All of these observations 
were made under identical conditions. Plants 275 and 276 grew beside 
each other in the same culture chamber, and a study of their curves shows 
how similar a four-wave curve is to one of three waves. It will be seen 
that the noon maximum comes two hours earlier in 276 than in 275, while 
the afternoon minimum comes two hours later in 276 than in 275. The 
other maxima, common to both, coincide; the difference in number of waves 
being due to the fact that 276 reaches its third maximum much earlier, 
sinks to a minimum, and then rises to a fourth maximum by the time 275 
