sept. 15,1925 Difference in Intemode Length of Sweet Clover 
589 
Table III .—Average length of first internode, average stem * length, and average 
internode length of seedlings , 63 days from sowing, January 12, 1922 
[Measurements in millimeters. Lettering same as for Table II] 
5-leaved 
6-leaved 
7-leaved 
Biennial 
Annua 
Biennial 
Annual 
Biennial 
Annual 
2066 
2140 
03464 
2143 
12055 
12060 
2066 
2140 
03464 
2143 
12055 
12060 
2066 
2140 
03464 
2143 
12055 
12060 
1 y 25 i 
: ■ • : i • ■ 
| i i i i i i i i i 
None. 
None. 
None. 
2.7 
9.1 
1.3 
14.7 
73.4 
11.7 
5.9 
25 
3.8 
3.1 
11.5 
1.7 
14.2 
72.6 
11.7 
4.5 
18.2 
2.7 
4.6 
15.7 
2.2 
13.7 
73 
11.9 
7 
26 
3.8 
5 
21.4 
3.3 
16.5 
76 
11.9 
11.1 
45 
4.8 
None. 
None. 
None. 
19 
93 
15 
9.2 
45.8 
7.3 
5.3 
35.8 
6.1 
16 
89.5 
14.7 
4.3 
16.5 
2 
2.2 
9 
1.1 
13.7 
97.3 
13.9 
5.8 
30 
4 
3.1 
13.3 
1.7 
16 
106.6 
15.1 
6 
23.1 
2.8 
5.5 
20.5 
2.5 
17.7 
120.5 
17.1 
8.4 
43.8 
5.2 
5 
20.5 
2.6 
16 
96.4 
13.4 
11.6 
55.8 
7.4 
4.2 
18 
2.3 
19.7 
121.2 
16.9 
9.9 
55.9 
7.7 
5.2 
42.7 
6.2 
17.8 
117.8 
17 
4 
25 
3 
2 
9.7 
1.1 
15 
120.7 
15.1 
6.4 
49.6 
6.1 
3.1 
13.5 
1.5 
17.1 
142.3 
17.9 
5.5 
24.7 
2.7 
4.6 
19 
2 
17.7 
120.5 
14.7 
None. 
None. 
None. 
4.2 
22 
2.5 
18 
135 
17 
11 
72.5 
8.8 
4 
18.4 
2.1 
21.3 
157.6 
19.5 
9.8 
72.4 
8.9 
5.4 
52.5 
6.7 
17.5 
146 
18.4 
As shown in Table II, the internode length of the annual forms 
was, under the normal length of day, markedly greater than that 
of the biennial forms (pi. 2, top row), though the difference was ont 
as great as it had been in seedlings grown out of doors in August- 
October. 
This fact is also brought out in Plate 3, which should be compared 
with Plate 1. The effect of decreased illumination was to shorten 
the internodes, both first and subsequent ones, but this shortening 
was, in the Arctic variety, 03464, confined to the first internode 
and was not shown by the subsequent internodes. Increased illumi¬ 
nation was marked by an elongation of all internodes. For the 
plants recorded in Table II, and leaving out the Arctic as peculiar, 
the ratio of average length of internodes between annual and 
biennial is: For three-leaved seedlings, normal day 1 to 0.58, short 
day 1 to 0.54, and long day 1 to 0.86; for four-leaved, normal day 
1 to 0.57, short day 1 to 0.8, and long day 1 to 0.87. 
Under the long day the difference between the internode lengths 
of annual and biennial has been decreased, the biennials responding 
relatively more to the long day than the annuals. The relative 
size of the first internode of annual and biennial has, however, 
remained fairly constant under long and short days, showing that 
the effect of illumination has been felt mostly in the internodes 
after the formation of the first leaf. For the first internode the ratios 
of annual to biennial are as follows (Table II): Three-leaved, normal 
day 1 to 0.61, short day 1 to 0.69, long day 1 to 0.73 ; for four-leaved, 
normal day 1 to 0.76, short day 1 to 0,78, long day 1 to 0.73. 
On January 12, 1922, a second set of the same numbers was sown 
and allowed to grow until March 16, 63 days after seeding. These 
seedlings were therefore older than those in the first set, and those 
under normal day had also had more hours of sunlight than those 
in the first set. In a few cases the number of seedlings of the seven 
and eight leaved sizes fell below 10 for each measurement, so these 
figures have less value than those in which more seedlings were 
available. The record for the eight-leaved seedlings is so imperfect 
that it is omitted (Table III). 
