DAILY RHYTHMS IN CERTAIN ROOTS 395 
Table 7 {Concluded) 
Time 
Temp. 
Dividing Cells 
Total 
Ave. 3 
Area 
Pro. 
Meta. 
Ana. 
Telo. 
"^T^p ^ 
3 1 ips 
5 A.M.. . 
25.0 
.988 
445 
53 
15 
36 
549 
319 
1.707 
319 
52 
12 
47 
430 
251 
279 
345 
66 
19 
30 
460 
268 
.918 
497 
71 
23 
39 
630 
427 
1475 
510 
87 
25 
59 
681 
461 
438 
381 
455 
89 
23 
66 
633 
428 
.850 
456 
50 
16 
44 
572 
452 
1 .261 
360 
6/1 
04 
37 
473 
375 
425 
437 
74 
14 
45 
570 
450 
7 A.M.. . 
24.0 
.808 
275 
50 
II 
52 
388 
340 
1. 140 
311 
60 
12 
38 
421 
369 
341 
258 
53 
13 
33 
357 
313 
•859 
240 
57 
10 
53 
360 
278 
1.290 
253 
63 
II 
52 
379 
292 
279 
305 
238 
65 
2 
40 
345 
266 
.791 
218 
46 
14 
36 
314 
285 
1.093 
221 
59 
6 
47 
333 
302 
294 
202 
55 
12 
56 
325 
295 
were placed in germinating pots at 9 A.M. and incubated for 72 hours at 
a temperature of 22°-23° C. Here also it will be seen that three waves 
occur in the 24-hour period. The maxima come at 3 P.M., 9 P.M., and 
I A.M.; and the minima at 11 A.M., 7 P.M., and 11 P.M. A comparison 
of curves 2 and 27 shows that the first two maxima of curve 2 each come 
just eight hours earlier (or 16 hours later) than two of curve 27, while the 
third maximum departs somewhat from this time relation. A similar 
relation exists between the minima. 
Let us now turn to evidence in support of the contention that the time 
of occurrence of maxima and minima is related to the time of initiation of 
activity and not to time of day. Curve 28 is the result obtained from root 
tips of the smooth-seeded variety grown at the same time and in the same 
incubator as those represented by curve 27, with the difference that the 
seeds for curve 28 were placed in the germinating pots at 2 P.M., instead of 
9 A.M. of the same day. In curve 28 three marked maxima occur with a 
very small fourth. Omitting, for the present, this extra small wave, we 
find maxima occurring at 7 P.M., 3 A.M., and 7 A.M., and minima at 3 P.M., 
II P.M., and 5 A.M. Now it will be seen that these seeds were started to 
germinate just 5 hours later than those of curve 27. Since root tips were 
cut and fixed every two hours, a difference of precisely five hours would not 
appear in the curves as such, but rather as a four- or six-hour d^ifference. 
Comparison of the two curves will show that the 7 P.M. maximum of curve 
28 is just four hours later than the 3 P.M. maximum of curve 27; similarly, 
the 3 P.M. and 11 P.M. minima of curve 28 are just 4 hours later than the 
