p 



1920] BROWN— STOMATA 



305 



2. 



normal 



the dark chamber, produced roundish, light green, elongated, 

 etiolated shoots which differed remarkably in form and structure 

 from those of the normal plant, and which exhibited structural 

 changes when transplanted in an outdoor environment that 

 brought them to resemble the normal shoot. 



3. The etiolated shoots lacked a cuticle, developed papillate 

 structures and stomata abnormal in form and position, and lacked 

 the cortical differentiation so characteristic of the normal shoot. 



4. The etiolated-greened shoots lost water rapidly at first. 

 Their air spaces increased rapidly by active intercellular splitting 

 of walls and by the collapse and death of cells; then a cuticle 

 appeared; cortical cells elongated, forming palisade tissue; and in 

 other respects the shoots approached the normal ones in structure. 



The study presented in part in this paper was made possible 

 through the interest of Dr. D. T. MacDougal, Director of the 

 Desert Laboratory, who furnished the etiolated material used, 

 and whose friendly criticism constituted a continual source of 

 inspiration. Acknowledgments are also due Professors John M. 



Coulter, Charles J. Chamberlain, and W. J. G. Land, of the 



University of Chicago, for numerous helpful suggestions. 



University of Arizona 



Tucson, Ariz. 



LITERATURE CITED 



1. Chamberlain, C. J., Methods in plant histology. 3d ed. University of 



Chicago Press. 1915. 



2. Cowles, H. C, Textbook of botany, vol. 2. New York: Amer. Book Co. 



400 



upon 



1911. 



3. Land, W. J. G., Micro technical methods. Bot. Ga2. j 



4. MacDougal, D. T. The influence of light and darkness 

 development. Mem. N.Y. Bot. Gard. 2: 



5. Rose, J. N., Contributions from the United States National Herbarium. 



12:402. 1909. 



6. Schleiden, M. J., Beitrage zur Anatomie der Cacteen. 1839. 



7. Spalding, Effie S., Mechanical adjustment of the Suaharo (Cereus gigan- 

 teus) to varying quantities of stored water. Bull. Torr Bot. Club 32 : 57-68. 

 1905, 



