CELL MEASUREMENT 
199 
group of cells derived from the original primary cell, in case the latter 
had undergone division. In many cases, of course, the shorter primary 
cells were undivided. Some mistakes in the differentiation of primary 
from secondary cells were doubtless made, but not enough to vitiate 
Table V 
Length in Mm. of Secondary Cells of Epicotyl of Plant Grown in the Light 
Class 
Section 
Entire 
Internode 
I 
2 
3 
4 
5 
6 
7 
8 
9 
10 
.003-027 
0 
0 
0 
0 
0 
0 
2 
0 
0 
0 
2 
.030-057 
3 
8 
10 
9 
9 
15 
II 
12 
77 
.060-.087 
3 
30 
41 
47 
52 
44 
57 
56 
360 
.O9O-.II7 
25 
'35 
35 
30 
33 
25 
31 
214 
.I2O-.I47 
4 
II 
9 
7 
8 
7 
I 
47 
•I50-.I77 
I 
3 
4 
the results. In Tables II, III, VII and VIII the divided and un- 
divided primary cells are separately enumerated. In Tables IV and 
IX are given the measurements of undivided primary and secondary 
cells, taken at random. The data of these two tables are therefore 
comparable with those of Kraus (1. c). Tables V and X concern the 
secondary cells only. Tables XI and XII give a convenient summary 
of the data in Tables I to X. 
Table VI 
Length in Mm. of Primary Epidermal Cells of Epicotyl of Plant Grown in Dark. The 
Cells were Taken at Random, without Regard to Whether or Not they had 
Undergone Secondary Division 
Class 
Section 
Entire 
Internode 
I 
2 
3 
4 
5 
6 
7 
8 
9 
ID 
.060-.II7 
8 
I 
5 
4 
I 
I 
4 
4 
7 
12 
47 
.120-177 
42 
9 
16 
15 
8 
14 
17 
II 
13 
23 
168 
.180-237 . 
34 
24 
22 
28 
41 
21 
21 
19 
16 
22 
248 
.24O-.297 
II 
30 
30 
30 
18 
27 
29 
28 
26 
14 
243 
•3OO-.357 
5 
23 
16 
II 
18 
15 
17 
12 
18 
II 
146 
•360-417 
8 
8 
7 
7 
13 
6 
8 
12 
9 
78 
.42O-.477.... ... 
4 
2 
I 
5 
8 
4 
8 
6 
7 
45 
•480-537 
I 
I 
2 
2 
I 
2 
8 
2 
2 
21 
.54O-.597 
2 
2 
4 
Beginning with section i, and reading downward in -all the columns 
in Table XI, it is seen that under both conditions of growth the epider- 
mal cells, whether primary, secondary, or taken at random, show a 
