REPORT OP THE SECRETARY 131 



COOPERATIVE WORK WITH THE BUREAU OF PLANT INDUSTRY, DEPARTMENT 



OF AGRICULTURE 



A first experiment has been carried out in the general plan of co- 

 operation between the United States Department of Agriculture and 

 the division, in the crop physiology and breeding investigations of 

 Dr. Walter T. Swingle. In this experiment the effects of controlled 

 radiation, humidity, and temperature on certain tropical and xero- 

 phji;ic plants were investigated in a preliminary way. The results 

 may be summed up as follows : 



First, it was found possible to maintain conditions which yielded 

 in the case of date palms, ten times greater growth rate than that 

 exhibited by the control plants in the greenhouse (pi. 2). Second, 

 humidity was shown to be a controlling factor in the growth of date 

 palms. Third, the ephedra under these conditions yielded two crops, 

 both larger than the single crop grown in the greenhouse. Fourth, 

 conditions maintained, perhaps due to the red-rich, blue-poor radia- 

 tion, yielded exceptional root development in both palms and pan- 

 dani- Fifth, pandani have shown exceptional offshoot development, 

 a matter of great significance in propagation of identical individuals. 

 If the same proves true of palms, as seems likely, this result is of 

 considerable practical importance. 



In this experiment the plant conditions and developments were 

 in the hands of Dr. Florence E. Meier, associate physiologist in the 

 Bureau of Plant Industry. Members of the division assisted during 

 the experiment by the development of control apparatus in connec- 

 tion with a propagating chamber for maintenance of constant 

 humidity and temperature. 



In further preparation for the cooperative program the Depart- 

 ment of Agriculture has constructed four additional individual 

 growth chambers of a larger and slightly modified design but in 

 general similar to the four already constructed by the division. A 

 humidifier to serve all the individual growth chambers has been 

 constructed by their shops and is in progress of installation. It 

 should be possible to begin experimentation vnth these individual 

 growth chambers some time during the coming fall. 



SPECTROSCOPIC DEVELOPMENTS 

 IIVFRA-BKD 



A large spectrograph, equipped with salt prisms, which will record 

 intensity distribution of radiation from the visible to 15/i in the deep 

 infra-red, is nearly completed. A preliminary grating set-up shows 

 102992—32 10 



