186 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1964 



The fact that the opening rate remains linear for as long as 20 hours 

 suggests that the magnitude of the final opening is directly propor- 

 tional to the amount of phytochrome produced by the initial red-light 

 exposure. However, any subsequent light treatments after the initial 

 ones show no correlation between the physiological system and the 

 measured in vivo pigment changes. Possible explanations for these 

 results are that only a small amount of the phytochrome is active, 

 that there is another form of the pigment as yet undetected, or that 

 the amount of phytochrome required to initiate the physiological re- 

 sponse cannot be detected by available instrumentation. At present, 

 our experimental data indicate that current theories are deficient and 

 need revision or modification. 



The action spectra for growth and tropic responses in Phycomyces 

 blakesleeanus have been extended into the near ultraviolet. The 

 spectra in this range indicate that either a second pigment system is 

 involved or that bleaching of the photoreceptor occurs. 



Experiments measuring the activity of extracts of sporangiophores 

 in the luciferin-luciferase assay system indicated that a 50-percent 

 change of activity occurs within 30 seconds after a blue-light stimulus. 

 There is no correlation between luciferin-luciferase activity and the 

 level of adaptation of sporangiophores. The activity is constant for 

 all levels of adaptation. Comparison between growing and nongrow- 

 ing samples indicated that all of the luciferin-luciferase activity 

 changes occur in the growing zones. These experiments show that one 

 of the early metabolic systems atfected by blue-light stimuli involves 

 high-energy phosphate compounds such as adenosine triphosphate 

 which are active in the luciferin-luciferase assay. 



The blue fluorescing unknown which was reported previously to be 

 present in large amounts in light-sensitive stages of sporangiophore 

 development has been isolated in large enough amounts to be identi- 

 fied. This material is a derivative of gallic acid and can be prepared 

 directly from gallic acid in the laboratory. Gallic acid is known to 

 occur at near-saturation concentrations in the sporangiophore, and 

 it is surprising that a material which correlates with the light- 

 sensitivity of sporangiophores is derived from material present in such 

 large amounts. 



To date, 80 samples of archeological, geological, and h3^drological 

 interest have been analj^zed by the carbon-dating laboratory, most of 

 them having been submitted in connection with research at the 

 Smithsonian. 



Carbon-14 determinations on the dissolved bicarbonate in ground 

 water have permitted estimates to be made on the flow rates in certain 

 mountain areas in Arizona. Such high-resolution age determination 

 is possible in certain situations owing to the rapid rise in atmospheric 



