Bums andHedden, Conditions influencing regeneration of liypocotyl 489 
on tlie parts still elongating. After a few days all elongation 
ceases and the epidermal cells of the liypocotyl are all practi- 
cally alike. Plants were allowed to grow longer periods with 
the result shown in the table: 
Age 
in days 
No. used 
Temp. 
Jime to 
regenerate 
No. Plants 
in giventime 
to buds 
5 
10 
30 max 
4 d 
5 
several 
15 
80 
30 „ 
7 d 
80 
11 
29 
60 
30 ,. 
7 d 
80 
11 
48 
60 
30 „ 
8 d 
60 
V 
55 
8 
30 „ 
19 d 
3 
few 
69 
16 
30 „ 
11 d 
4 
escli. 2 
Linum. Relation of age to regeneration. 
This shows that the time reqnired for the first bnds and 
the number of these bnds decreases in a general way with the 
age of the seedling. 
The buds on old seedlings appear near the base of the 
hypocotyl. 1t wonld thns appear tliat this part of the hypoco- 
tyl can prodnce bnds easier than other parts. It will be recalled 
in this connection that some plants prodnce such bnds at the 
base, after the movement of food material to the flowers and 
frnits ceases. This part is especially disposed to prodnce bnds. 1 ) 
Gfravity. Experiments on this line failed to show that 
the position and nnmber of the bnds, and the anisophylly were 
in any way dependent npon gravity. 
Light. A large nnmber of seedlings were revolved on the 
klinostat in a horizontal position in the plant honse for 14 days 
in a diffuse light. No regeneration took place, and it seemed 
at first to show that gravity was an important factor. However, 
a second set were tnrned the same way in another place, in 
bright light and every plant regenerated in 9 days. Decapitated 
seedlings were then tnrned to give eqnal illnmination on all 
sides and bnds developed eqnally on all sides and with no pre¬ 
ference for eit her end. 
A third set of seedlings were then tnrned horizontally in 
the laboratory with the wonnded end toward the sonth window 
and in 8 days bnds, began to appear. They were however, 
crowded toward the wonnded end. 
A fonrth set of decapitated seedlings were. placed in a 
horizontal position in a sonth window and a remarkable arrange- 
ment of bnds was fonnd in some cases. At first the bnds 
appeared on the npper side near the base. The hypocotyl 
however, gradnally tnrned np at the end and bnds appeared on 
i) Goebel. Über Regeneration im Ptianzenreicli. (Biol. Centralblatt. 
1902. p. 385.) 
