6i6 FACTORS AFFECTING GROWTH 



Shirley, H. L. The influence of light intensity and light quality upon the 

 growth of plants. Amer. Jour. Bot. i6: 354-390. 1929. 



Shirley, H. L. Light as an ecological factor and its fneasure?nent. Bot. Rev. 

 i: 355-381. 1935. 



Shirley, H. L. The effects of light intensity upon plants. In Biological 

 effects of radiation. II. 727-762. B. JVI. Duggar, Editor. McGraw- 

 Hill Book Co. New York. 1936. 



Stiles, W. On the cause of cold death of plants. Protoplasma 9: 459-468. 

 1930. 



Thompson, H. C. Temperature as a factor affecting flowering of plants. 

 Proc. Amer. Soc. Hort. Sci. 30: 440-446. 1933. 



Thompson, H. C, and J. E. Knott. The effect of temperature and photo- 

 period on the grozvth of lettuce. Proc. Amer. Soc. Hort. Sci. 30: 507- 

 509. 1933. 



Withrow, R. B., and H. IVI. Benedict. Photoperiodic responses of certain 

 greenhouse annuals as influenced by intensity and ivavelength of artificial 

 light used to lengthen the daylight period. Plant Physiol. 1 1 : 225- 

 249. 1936. 



Zimmerman, P. W., and W. Crocker. Toxicity of air containing sulfur 

 dioxide gas. Contr. Boyce Thompson Inst. 6: 455-470. 1934. 



Zimmerman, P. W., and A. E. Hitchcock. Root formation and floivering of 

 dahlia cuttings luhen subjected to different day lengths. Bot. Gaz. 87: 

 1-13. 1929. 



Zimmerman, P. W., and A. E. Hitchcock. Tuberization of artichokes regu- 

 lated by capping stem tips ivith black cloth. Contr. Boyce Thompson 

 Inst. 8: 311-315- 1936. 



