B u r 11 s aiid H ed d eii , Coiiditions iiiHueuciug regeneratiou of 113'pocotyl. 389 



on the parts still elongating. After a few days all elongation 

 ceases and the epidermal cells of the hypocotyl are all practi- 

 cally alike. Plants were allowed to grow longer periods with 

 the result shown in the table: 



Linnm. Relation of age to regeneratiou. 



This shows that the time reqiiired for the first buds and 

 the number of these buds decreases in a general wa}^ with the 

 age of the seedling, 



The buds on old seedlings appear near the base of the 

 hypocotyl. It woukl thus appear that this part of the hypoco- 

 tyl can produce buds easier than other parts. It will be recalled 

 in this connection that some plants produce such buds at the 

 base, after the movement of food material to the flowers and 

 fruits ceases. This part is esj^ecially disjDosed to produce buds.^) 



Gravity. Experiments on this line failed to show that 

 the Position and number of the buds, and the anisophyll}- were 

 in any way dependent upon gravity. 



Light. A large number of , seedlings were revolved on the 

 klinostat in a horizontal position in the plant house 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 tm^ned the same way in another place, in 

 bright light and every plant regenerated in 9 days. Decapitated 

 seedlings were then turned to give equal illumination on all 

 sides and buds developed equally on all sides and with no ])re- 

 ference for either end. 



A third set of seedlings were then turned horizontally in 

 the laboratory with ihc wounded end toward the south window 

 and in 8 days Ijuds began to appear. They were however, 

 crowded toward the wounded end. 



A fourth set of decapitated seedlings were placed in a 

 horizontal position in a south window and a remarkable arrange- 

 ment of buds was found in some cases. At first the buds 

 appeared on the upi)er side near the base. The hypocotyl 

 however, gradually turned u]) at the end and buds aj^peared on 



1) Goebel, Über Regeneration ini Pllanzenreicli. (Riol. Ceutralblatt. 

 1902. p. 385.) 



