22 Newcombe, Sensitive Life of Aaparagus phtmosus. 



then rose to 20° below vertical for 2 days — then declined to 

 45° and experiment ended. Total hight of shoot 109 cm. Total 

 period of Observation 46 days. 



In the light this shoot would have niade tbe diageotropic 

 curve at a hight of 15 cm to 20 cm. 



Tbe following is an example of 4 shoots which were never 

 exposed to the light, which were not observed closely for details 

 of nutation, bnt were followed in their later behavior to see 

 whether they would adopt a constant direction of growth: 



5) Shoot remained orthotropic for 18 days after appearing 

 above ground, being then 23 cm tall. Mature assimilating shoots 

 next older than one in the opaque cone averaged 21 cm vertical 

 portion. From the beginning on thru a total period of 150 days, 

 the shoot made a total growth of 177 cm, the tip then dying and 

 a lateral branch being sent out later which continued the growth. 

 During the whole period, after the first 18 days, the tip of the 

 main axis alternately declined from 45° to 70° and rose to the 

 vertical, remaining never more than a few days (1 to 8) in one 

 Position. The record shows the tip was vertical when the shoot 

 was 48 cm tall, 61 cm, 79.5 cm, and 172 cm. The last hight 

 was attained only 8 days before the death of the tip. 



3. Behavior of shoots exposed to light for one to 

 several days. As clearly as the experiments illustrated by the 

 foregoing examples demonstrate the inability of the plant in the 

 absence of light to retain its plagiogeotropism, after relinquishing 

 its negative geotropism, not less clearly does another set of ex- 

 periments demonstrate the specific ability of light to make per- 

 manent this diageotropism even when light is cut of for days before 

 the plant shows this reversal of response. This series of experiments 

 has included the study of the behavior of 21 shoots of Asparagus 

 from which light has been exeluded after these shoots had been 

 exposed to light from one to many days. The shoots were selected 

 for exclusion from the light after they had attained various hights 

 varying from 1 mm above ground to 8 cm above ground, the latter 

 size belonging to shoots which were nearly ready to begin the 

 diageotropic curve. The preparations were kept in the dark-room, 

 or opaque covers as paper cones were used as in the former set 

 of experiments, the assimilating shoots in the same pots being 

 allowed to continue their funetions. Representative experiments 

 are given here. 



6) Pot with a young shoot 8 cm above ground was removed 

 from greenhouse to dark-room. Tip was already nutating pre- 

 paratory to going to the transverse position. First day in dark, 

 tip kept vertical position — second day, tip declined to 25° from 

 vertical — after some nutation, tip reached the horizontal position 

 on 4th day after placing in dark-room, held this position per- 

 manently and unfolded its branches, including needles. 



7) Shoot 7 cm tall when covered — in the dark erect for 

 3 days — then declined 30° when 11 cm tall — 5th day declined 

 to 35° — 7th day decliged to80° — 8th day declined to 90° — 



