Some Effects of Radiant Energy in Relation to Etiolation.

Numerous investigators have worked on the problem of determining the effect of small quantities of visible radiant energy on seedlings and other plants with stored foods. The literature is extensive and goes back over one hundred years. MAcDOUTGAL (6) has thoroughly reviewed the work before 1900 while TRUMPF (9) and BURKHOLDER (1) have reviewed this and much of the later work. The work before 1900 established the fact that visible radiant energy alone could be considered capable of initiating the morphological differences resulting when seedlings and plants with storage organs received small amounts of energy but not enough to carry on significant amounts of photosynthesis. Since 1900 more quantitative investigations have been carried out by TRUMPF (9), PRIESTLY (7), WITHROW (13), and WENT (11). The following experiments were an attempt to give further information on the quantitative responses of certain seedlings to irradiation, and to find out more about the internal mechanism causing these responses.