3S8 B u r n s niul II t'ddcu. (\)iuliti()iis iullueiiciug regeneratioii nf liypocotyl. 



B. Woiinded seedlings. Moi sture. The effect. of 

 moisture on production of tliese buds on tlie liypocotyl is shown 

 in the following: 



A)iin-rhlnnm seedling!> were prepared ns above described 

 and one set placed in a damp Chamber, tlic 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 about one day in favor of the damp atmosphere. 

 The same held true for Linum. In the case of Linaria., this 

 was not the case although there was a slight advantage in favor 

 of the plants kept in the damp. In 140 seedlings, plants deve- 

 loped buds in three days regardless of the moisture content of 

 the air, while of 35 i)lants kept in a damp chamber 5 ])roduced 

 buds in four days and in another crock of the same niimber in 

 dry atmos])here one produced a bud in five days. 



The effect of moisture is more pronounced in the number 

 of buds formed. In all cases the plants in the darnp chamber 

 2)roduced many more buds. 



Temperature. The temperature experiments were con- 

 ducted moistly with Linum. The experiments were set up like 

 the preceding, except tliat the varying factor was temperature. 

 The results obtained were as foUows; plants at 10 — 15 ^ in 

 damp Chamber produced buds in 10 days, those at 25 ° in 8 days, 

 while four seedling\s out of eleven at 30^ — 35^ produced buds in 

 four days. Higher temperatures killed the plants. 



Not only did the plants in higher temperatures joroduce 

 buds sooner hixi the number of buds produced was always greater. 



No Seedlings 



Temp. 



No days to 

 regeneralt 



Size 



Moisture 



12 

 8 

 4 



11 



10—15 ' 



25 



25 

 30—35 



10 



cS 



9 

 4 



so cm 



11 



wet 



Linum. 



Relation of temperat\ire to regeneration. The table sliow tlie 

 results of one set of experiments. 



Age. Experiments w^ere conducted with Linum to deter- 

 mine if possible at what age the cells of the liypocotyl lose the 

 ability to produce these buds. It was hrst determined what 

 age the liypocotyl ceaaes to grow. To determine this the 

 hy^^ocotyl at different ages was marked every 2 mm with India 

 ink and observed later. These experiments showed that the 

 last part to stop elongating is the part immediately beneath the 

 cotyledon. The liypocotyl Usually ceases elongating entirely 

 wlien it is 2,5 to 3 cm long, under ordinary conditions. 



A comparison of the figures already given sliow that on 

 young seedlings there is no tendency toward developing shoots 



