26 Raymond John Pool 
In conclusion I wish to express my greatest appreciation and 
thanks to Professor Doctor Frederic E. Clements of the Uni- 
versity of Minnesota who suggested this study, and who was my 
adviser during all the field work; also to Professor Doctor 
Charles E. Bessey of the University of ‘Nebraska, to whom I am 
indebted for much counsel and advice during the progress er this ; 
study. ; 
LITERATURE 
CLEMENTs, F. E. 
Research Methods in Ecology. 1905. 
CLEMENTS, E. S. 
Relation of Leaf Structure to Physical Factors. Trans. Am. 
Micros. Soc., 25. 1905. 
DeBary, A. 
Comparative Anatomy of the V egetative Organs of the 
Phanerogams and Ferns. 1884. 
HABERLANDT, G., 
Vergleichende Anatomie des assimilatorischen Gewebsystems 
der Pflanzen. Prings. Jahrb., XIII, 74. 
Physiologische Pflanzenanatomie, sae 
MacDouaat, D. T. 
Problems of the Desert. Plant World, vol. 11, no. 2, Feb. 
1908. 
PARKIN, J. 
Ann. Bot. 14:193-214. 1900. 
436 
