366 Epinasty and Hyponasty of Raphanus Cotyledons. 



and lined with tin and tar felt, so as to preclude all pos- 

 sibility of the entrance of light. 



After 48 hours. Same curvatures as in A, but cotyledons not opened as 

 much. Strongly etiolated. 



After 72 hours. Cotyledons hyponastic. Not separated, turned down- 

 wards. 



After 92 hours. Cotyledons hyponastic, upright. Not separated. 



After 96 hours. Cotyledons hyponastic. Slightly separating. 



After 116 hours. Cotyledons strongly hyponastic. Slightly separating. 



After 140 hours. Cotyledons strongly hyponastic. Unchanged. 



3. Faint illumination. — Made by placing the saucers un- 

 der square frames, covered with shades of cloth. 



After 48 hours. Cotyledons separating (opening) upper epinastic, lower 

 hyponastic, turned downwards. 



After 72 hours. Upper cotyledons epinastic, lower hyponastic. The ten- 

 dency is toward parallelism of the cotyledons. 



After 96 hours. Cotyledons hyponastic. As compared with No. i, (Dif 

 fuse light) they are more so at this age. 



After 120 hours. Cotyledons hyponastic. Not separating. 



After 144 hours. Cotyledons hyponastic. Not separating. 



After 168 hours. Cotyledons hyponastic. Separating. Upper cotyledon 

 with shorter pedicel, lower with longer. 



After 192 hours. Cotyledons hyponastic. Separating. 



4. Illumination from the side. — Produced by placing sau- 

 cers at the back of low boxes with one side wanting, and expos- 

 ing open side toward strongest light direction, i. e., the path of 

 the sun. In this manner we get light coming mainly from the 

 one direction, and by placing the seedlings so that illumination 

 may be directed toward the side of the cotyledons we may study 

 this condition. Light here is necessarily somewhat diffuse. By 

 arranging a mirror strong illumination may be secured. 



After 48 hours. Upper cotyledons epinastic, lower hyponastic. 



After 72 hours. Cotyledons turned downward. Upper epinastic, lower 

 hyponastic. It is to be noted that the upper cotyledons are presented 

 toward the direction of the incident light rays. 

 Three saucersful placed in opposite direction, i. e., with 



lower cotyledons toward light direction. 



After 96 hours. The result has been that those so placed have turned 

 around, and persist in presenting their upper cotyledons toward the 

 light. Cotyledons hyponastic. 



After 120 hours. Those turned yesterday so as to have side illumination, 

 have turned around and persist in presenting their faces to the inci- 

 dent light rays. Hyponastic. 



5. Strong illuinination from end (toward notch between 

 cotyledons). Planted under same conditions as No. 4. 



