368 Epinasty and Hyponasty of Raphanns Cotyledons. 



After 12 hours. Put in diffuse light. Seeds swollen and sending out 

 roots, but not opened enough to see different curvatures. This seems 

 to be the most favorable condition for germination. 

 After 24 hours. Put in dark. 

 After 42 hours. Put in strong illumination. Upper cotyledons epinastic, 



lower hyponastic. 

 After 48 hours. Put in dark. 



After 60 hours. Put in strong illumination. Cotyledons barely opened, 

 showing no tendency to curvature which might separate the cotyle- 

 dons. 

 After 66 hours. Put in diffuse light. Cotyledons separated. The epin- 

 asty of the upper has become less apparent, as has the hyponasty of 

 the lower, turned downwards. 

 After 72 hours. Put in dark. 



After 84 hours. Put in diffuse light. Cotyledons slightly epinastic, up- 

 right. 

 After 90 hours. Put in dark. Cotyledons hyponastic. Not separated. 

 After 108 hours. Put in strong illumination. Cotyledons hyponastic. Not 



separated. 

 After 114 hours. Cotyledons hyponastic, but less so than 6 hours ago. 



Not separating. 

 After 120 hours. Put in dark. Cotyledons slightly epinastic. Separating. 

 After 132 hours. Put in diffuse light. Cotyledons epinastic. Separated. 

 After 144 hours. Put in dark. Epinastic. 



After 162 hours. Put in strong illumination. Cotyledons slightly hypon- 

 astic. 

 After 168 hours. Put in dark. Cotyledons hyponastic but less so than 6 



hours ago. 

 After 180 hours. Put in strong illumination. Cotyledons slightly hypon- 

 astic. 

 After 186 hours. Cotyledons epinastic. 



To summarize these results we find that the cotyledons of 

 Raphanus sativa are always epinastic when grown imder normal 

 conditions of light, temperature and moisture. Considering the 

 temperature and moisture the same in all cases, we find in res- 

 pect to these organs, that when grown under a condition of 

 total darkness, diffuse or faint hght, they are always hyponastic. 

 When grown in total darkness the cotyledons are very sensi- 

 tive to the influence of hght. 



In the case of one trayful, y2 hours old, which was exposed 

 to diffuse Hght while taking notes, the cotyledons curved per- 

 ceptibly, so that they were but slightly hyponastic. It is to be 

 noted also that after 96 hours in the dark, epinastic curvature 

 of the hypocotyls took place, thereby separating the cotyledons. 

 The illumination in the case of the light coming from only 

 one direction must be toward the notch between the cotyledons. 



