94 AJsnsruAL report Smithsonian institution, 1961 



La Jolla. Carlton W. Tillinghast, Jr., became the new assistant 

 director. 

 As of June 30, 1961, 309 persons were employed at the Observatory. 



BUILDINGS AND EQUIPMENT 



In addition to two other leased buildings, the Astrophysical Obser- 

 vatory occupies the recently completed Harvard University Space 

 Science Building on the grounds of the Harvard College Observatory. 

 Dedication took place in December 1960. 



FUNDS AVAILABLE, FISCAL YEAR 1961 



Satellite-tracking Program (NASA) $3,900,000 



Celescope (NASA 51-60) 695,543 



Army Ballistics Missile Agency (ABMA) 19,964 



Air Force Contract 1596 22, 547 



Air Force Contract 6627 4, 998 



Air Force Contract 7414 67, 786 



National Aeronautics and Space Administration Grant H-3647 50, 000 



National Science Foundation Grant 16337 20, 000 



National Science Foundation Grant 16067 25, 000 



Total 4, 805, 838 



DIVISION OF RADIATION AND ORGANISMS 

 Prepared by W. H. Klein, Chief of the Division 



The research activities of the Division were continued in the general 

 field of photobiology, and the principal efforts were directed toward 

 a more complete description of the regulatory responses of plants 

 that are mediated by radiant energy. The technics of biochemistry, 

 biophysics, cytology, and plant physiology were used in evaluating 

 both qualitatively and quantitatively the metabolic and morphological 

 changes occurring at the cellular and subcellular level in such photo- 

 regulatory processes. 



The time course of chlorophyll synthesis at various stages of de- 

 velopment for dark-grown Black Valentine bean plants was deter- 

 mined. A lag phase in the rate of chlorophyll synthesis occurs when 

 seedlings are 6 or more days old. The rate of chlorophyll synthesis 

 can be increased by a low-level pretreatment of red radiant energy, 

 and this red effect can be completely eliminated by following it with 

 far-red radiant energy. Since it appeared to be a possibility that 

 the rate-limiting factor might be a substance which was depleted 

 from the leaves or cotyledons at about 6 days or synthesized as a 

 result of the red pretreatment, a number of compounds were tested 

 by infiltrating leaves to determine their effect on the lag phase. In 

 leaves infiltrated with delta amino levulinic acid, chlorophyll syn- 

 thesis was found to occur without a lag phase diu'ing the first hour of 



