SECRETARY’S REPORT 93 
morphogenic responses, such as seed germination, seedling develop- 
ment, and flowering. 
In studying the effect of blue light on growth, Dr. Walter Shrop- 
shire, Jr., investigated the detailed action spectrum of the first 
positive tip curvature of the oat coleoptile, using a grating mono- 
chromator and irradiating the coleoptile at 10 my steps from 350 to 
520 mp. From this action spectrum, it is concluded that the active 
pigment initiating the growth response is yellow, probably carotenoid 
in nature, with absorption maxima at 410-415, 440-445, and 470-475 
mp. <A flavin photoreceptor appears unlikely, although a peak was 
observed in the near-ultraviolet at 370 mp. The curvatures in the 
ultraviolet may be due to screening across the plant tissue by an in- 
active secondary pigment with an absorption at about 370 mp. 
PUBLICATIONS 
WitTHROW, R. B.; KieIn, W. H.; and Hustap, V. Action spectra of photo- 
morphogenic induction and its photoinactivation. Plant Physiol., vol. 32, pp. 
453-462, 1957. 
WoLrr, JOHN B., and Pricr, Leonarp. Terminal steps of chlorophyll @ biosyn- 
thesis in higher plants. Arch. Biochem. and Biophys., vol. 72, pp. 293-301, 
1957. 
OTHER ACTIVITIES 
Various staff members attended several national and international 
meetings to present results of research in progress. Early in the year, 
Dr. Robert B. Withrow and Dr. Alice P. Withrow attended the 
Gordon Conferences at Meriden, N.H., where Dr. Robert B. Withrow 
lectured on “Photocontrol of Growth by Red Light.” At the annual 
meeting of the American Institute of Biological Sciences, Stanford, 
Calif., the following papers were presented : 
Stimulation of protochlorophyll synthesis in dark-grown bean leaves by irradia- 
tion with low energy, by J. B. Wolff, L. Price, and R. B. Withrow. 
Kinetics of the far-red inactivation of photomorphogenesis in the bean hook, by 
W. H. Klein, R. B. Withrow, and V. Hlstad. 
Interaction of red and far-red radiant energy in modifying X-ray-induced 
chromatid aberrations in broad bean, by C. C. Moh and R. B. Withrow. 
The mode of action of light and temperature, by R. B. Withrow. 
Status of action spectrum and photoreceptor pigment in phototropism, by W. 
Shropshire, Jr. 
An International Symposium on Photoperiodism and Related Phe- 
nomena in Plants and Animals, sponsored by the National Research 
Council and the National Science Foundation, was organized under 
the chairmanship of Dr. Robert B. Withrow and held at Gatlinburg, 
Tenn. in October 1957. Papers entitled “Interaction of Growth Fac- 
tors with the Photoprocess in Seedling Growth,” by W. H. Klein, and 
“A Kinetic Analysis of Photoperiodism,” by R. B. Withrow, were 
presented at the symposium. 
