xi, c, 5 Copeland: Growth Phenomena of Dioscorea 231 
Table III . — Groivth of tubers of Dioscorea during one week, May 9-16. 
Col- 
lege 
No. 
Illumination. 
Growth 
in millimeters. 
Without soil. 
Tuber No. — 
In soil. Tuber 
No.- 
i 
2 
3 
4 
5 
6 
7 
8 
9 
10 
1 
2 
3 
8 
14 
2 
58 
3 
77 
64 
111 
952 
70 
38 
12 
9 
15 
16 
6 
48 
4 
27 
14 
25 
1369 
15 
32 
9 
9 
58 
9 
28 
40 
958 
17 
9 
6 
20 
35 
65 
2 
19 
33 
52 
40 
519 
191 
960 
115 
329 
15 
121 
246 
85 
137 
57 
42 
42 
288 
J Dark 
109 
309 
70 
749 
419 
331 
15 
156 
701 
580 
64 
717 
8 
13 
306 
17 
43 
9 
2 
25 
60 
85 
959 
5 
185 
7 
19 
8 
5 
34 
44 
88 
) Dark - 
73 
29 
208 
21 
312 
324 
52 
11 
262 
286 
998 
489 
74 
6 
769 
320 
788 
399 
338 
470 
743 
423 
10 
] Dark 
3 
21 
22 
8 
11 
6 
906 
8 
966 
9 
3 
14 
160 
1G1 
168 
16 
218 
330 
79 
244 
262 
344 
1101 
634 
116 
14 
103 
614 
61 
23 
122 
149 
I Dark 
34 
42 
37 
40 
1 
6 
1 
171 
60 
84 
329 
68 
124 
17 
10 
9 
159 
82 
64 
71 
159 
51 
21 
46 
1 
20 
84 
23 
1094 
9 
69 
7 
14 
6 
16 
19 
8 
938 
10 
16 
10 
7 
86 
140 
10 
24 
17 
20 
1 
35 
9 
During the whole period of experiment, the plants exposed to 
light reached a decidedly greater average length, as is shown 
by Table IV. 
Table IV . — Length of longest shoot and average of most active plants. 
College 
In light. 
In darkness. 
No. 
Longest. 
Average. 
Longest. 
Average. 
88 
mm. 
3,860 
mm. 
3,457 
mm. 
1, 690 
mm. 
1,321 
329 
1,967 
1,324 
860 
634 
331 
4, 780 
2,540 
1,900 
1,695 
938 
2,235 
792 
1,052 
672 
952 
722 
496 
682 
430 
956 
865 
790 
2, 844 
924 
958 
2,591 
1,454 
919 
678 
959 
2, 540 
1,455 
448 
960 
2, 718 
1,371 
2, 150 
1,160 
1094 
1, 107 
963 
421 
375 
1101 
2, 661 
2,010 
875 
1369 
1,900 
1,342 
1, 130 
945 
