A. 11'. (iALSTON AND RAVIN I) AR KAUR 68<) 



the comparative growth characteristics of green and etiolated plants 

 have been subjected to a much closer scrutiny than they have yet 

 had. The investigations reported in this j)aper are part of a general 

 program aimed at obtaining data which may aid in the elucidation 

 of the problems mentioned above. 



Materials and Methods 



Etiolated plants. All plants were obtained from seeds of Alaska 

 peas (Pisuni sativum L.) purchased from Associated Seed Growers, 

 inc., New Haven, Connecticut. The seeds were soaked in tap water 

 for 4 horns in darkness and sown in carefully washed, tap-water 

 saturated vermiculite (Mica-Grow Type B, supplied by Piatt Seed 

 Company, Branford, Connecticut) in polyethylene trays. The seed- 

 lings were allowed to grow in a darkened cabinet, in a dark room, 

 maintained at 27 ± 1°C. Dining manipulation, they were exposed 

 as sparingly as possible to a dim green light about 30 cm distant. 

 This light source consisted of a 15-watt Sylvania green fluorescent 

 lube ^vrapped with 3 layers each of green and amber DuPont cello- 

 phane, and was found to be inactive both phototropically and photo- 

 morphogenetically. 



All sections were excised from 7- to 8-day-old plants with recurved 

 terminal buds, except for experiments in which the effect of the bud 

 configuration on growth was studied. In general, 5 mm sections cut 

 ca. 2 mm below the apical crook were used. 



Light-groii'u peas. Alaska peas were sown in coarse "Zonolite" 

 vermiculite in 4 X ^ X ^ inch plastic boxes in three controlled- 

 condition rooms maintained at ca. 23 °C and at photoperiods of 8, 

 16, and 24 hours. The j^lants were automatically subirrigated twice 

 daily with a nutrient solution consisting of 120 g of Hyponex (Hy- 

 droponics Chemicals Company, Copley, Ohio) per 100 1 tap water. 

 The plants received ca. 1500 foot-candles of a mixture of fluorescent 

 and incandescent lights, and were used in the experiment at an age 

 of 14-24 days. All sections were excised immediately below the apical 

 bud. 



Sections 1 mm to 5 mm in length of both etiolated and green pea 

 stems, were cut by the use of a guillotine described earlier (8) . The 

 longer sections, 10 mm to 20 mm, were excised by a properly spaced 

 double-bladed cutting tool. The sections were first randomized in 

 distilled water, and lots of 10 sections were then floated on 5 ml of 

 growth medium in 5 cm petri dishes. The etiolated sections were 

 permitted to grow in a completely dark growth cabinet in a dark 



