388 Bums and H e d d e n, Conditions inüuencing regeneration of hypocotyl. 
B. Wounded seedlings. Moisture. The effect of 
moisture on production of these buds on the hypocotyl is shown 
in the following: 
Antirrhinum seedlings were prepared as above described 
and one set placed in a damp chamber, the other in the labo- 
ratory where the air was much drier. Other factors were of 
course held as nearly constant as possible, Antirrhinum showed 
a difference of abont one day in favor of the damp atmosphere. 
The same held true for Linum. In the case of Linaria , this 
was not the case althongh there was a slight advantage in favor 
of the plants kept in the damp. In 140 seedlings, plants deve- 
loped bnds in three days regardless of the moisture content of 
the air, while of 35 plants kept in a damp chamber 5 produced 
buds in four days and in another crock of the same number in 
dry atmosphere one produced a bud in free days. 
The effect of moisture is more pronounced in the number 
of buds formed. In all cases the plants in the damp chamber 
produced many more buds. 
Temperature. The temperature experiments were con- 
ducted mostly with Linum. The experiments were set up like 
the preceding, except that the varying factor was temperature. 
The results obtained were as follows; plants at 10—15° in 
damp chamber produced buds in 10 days, those at 25 0 in 8 days. 
while four seedlings out of eleven at 30—35° produced buds "in 
four days. Higher temperatures killed the plants. 
Hot only did the plants in higher temperatures produce 
buds sooner but the number of buds produced was alwavs greater. 
No Seedlings 
Temp. 
No days to 
regeneralt 
Size 
Moisture 
12 
10—15 
10 
25 cm 
wet 
8 
25 
8 
4 
25 
9 
V 
11 
30—35 
4 
Linum. Relation of temperature to regeneration. The table show the 
results of one set of experiments. 
Age. Experiments were conducted with Linum to deter- 
mine if possible at what age the cells of the hypocotyl lose the 
ability to produce these buds. It was first detennined what 
age the hypocotyl ceaaes to grow. To determine this the 
hypocotyl at different ages Avas marked e\ r ery 2 mm with India 
ink and observed later. These experiments slioAved that the 
last part to stop elongating is the part immediately beneath the 
cotyledon. The hypocotyl asually ceases elongating entirely 
Avhen it is 2,5 to 3 cm long, under ordinary conditions. 
A comparison of the figures already given sIioav that on 
young seedlings there is no tendency toward developing shoots 
