400 
RAY C. FRIESNER 
in roots from bulbs of Allium Cepa, i.e., the times of maxima of cell division 
are near the times of minima of elongation and vice versa. It should be noted 
that the observations of de Wildeman (39) and Ward (38) were made directly 
upon the dividing cell while it was dividing. The two processes were 
observed in one and the same cell. Such direct observation in the case of 
root tips is, of course, out of the question. 
Experimental 
Pisum sativum. In table 10 the times of maxima and minima of elon- 
gation and cell division in Pisum are compared. It is seen that in both the 
wrinkled-seeded and smooth-seeded varieties the times of maxima of elon- 
Table 10. Comparison of Maxima and Minima of Elongation and Cell Division in Pisum 
Wrinkled Variety 
Elongation Maxima (see table 2) 
Cell Division Minima (see curve 2) . . . . 
Elongation Minima 
Cell Division Maxima 
2-6 P.M. 
3 P.M. 
10 A.M.-2 P.M. 
I P.M. 
8-12 P.M. 
9 P.M. 
6-8 P.M. 
5 P.M. 
4-6 (10) A.M. 
II A.M. 
2-4 (6) A.M. 
5 A.M. 
Smooth Variety 
Elongation Maxima (see table 2) 
Cell Division Minima (see curve 27) . . . 
Elongation Minima 
Cell Division Maxima 
5-7 P.M. 
II P.M. 
1-3 P.M. 
3 P.M. 
II P.M.-i A.M. 
II P.M. 
9 P.M. 
9 P.M. 
5-7 A.M. 
7 A.M. 
3-5 A.M. 
I A.M. 
gation correspond very closely to the times of minima of cell division, and 
vice versa. A single exception is found in each variety: in the wrinkled- 
seeded variety the 11 A.M. minimum of cell division comes considerably 
later than the corresponding maximum of elongation in the majority of 
plants; and in the smooth-seeded variety the 11 A.M. minimum of cell 
division comes much earlier than the corresponding maximum of elongation. 
With the exception of this one divergence in each case there is a very close 
reciprocal relation existing between the rapidity of elongation and the 
number of cells undergoing division. 
Table i i . Comparison of Maxima and Minima of Elongation and Cell Division in Lupinus 
Elongation Maxima (see table 3) 
1-3 P.M. 
7 P.M.-I A.M. 
5-7 A.M. 
Cell Division Minima 
Curve I 
3 P.M. 
I A.M. 
5 A.M. 
Curve 13 
7 P.M. 
I A.M. 
7 A.M. 
Elongation Minima 
II A.M.-i P.M. 
5-9 P.M. 
3-5 A.M. 
Cell Division Maxima 
9 A.M. 
II P.M. 
3 A.M. 
Curve 13 
I P.M. 
II P.M. 
3 A.M. 
Lupinus albus. In table 1 1 the maxima and minima of elongation and 
cell division in Lupinus are compared. It will be seen that here again there 
