iv 
TABLE OF CONTENTS 
Distribution of the Malvaceae in southern and western Texas (with 
one text figure) Herbert C. Hanson 192 
Note on the histology of grain roots (with four text figures) 
Grace A. Dunn 207 
North American Pipers of the section Ottonia (with Plates V-VHI) 
William Trelease 212 
Monocarpy and pseudomonocarpy in the cycadeoids (with one text 
figure and Plates IX-XH) G. R. Wieland 218 
No. 5, May 
Isoachlya, a new genus of the Saprolegniaceae (with Plates XHI 
and XIV) C. H. Kauffman 231 
The transmission of Rhus poison from plant to person 
James B. McNair 238 
The type concept in systematic botany. . . A. S. Hitchcock 251 
The relation of certain nutritive elements to the composition of the 
oat plant (with two text figures) James Geere Dickson 256 
No. 6, June 
Specialization and fundamentals in botany. .Joseph Charles Arthur 275 
Certain aspects of the problem of physiological correlation 
C. M. Child 286 
Water deficit and the action of vitamines, amino-compounds, and 
salts on hydration D. T. MacDougal 296 
The eusporangiate ferns and the stelar theory (with seven text figures) 
D. H. Campbell 303 
The relation of plant pathology to human welfare F. L. Stevens 315 
No. 7, July 
The relation of crop-plant botany to human welfare 
Carleton R. Ball 323 
Correlations between anatomical characters in the seedling of Phaseolus 
vulgaris (with eight text figures) 
J. Arthur Harris, Edmund W. Sinnott, John Y. Pennypacker, 
and G. B. Durham 339 
A quantitative study of the effect of anions on the permeability of 
plant cells H (with one text figure) Oran L. Raber 366 
The mechanism of root pressure and its relation to sap flow 
James Bertram Overton 369 
No. 8, October 
The vascular anatomy of hemitrimerous seedlings of Phaseolus vulgaris 
J. Arthur Harris, Edmund W. Sinnott, John Y. Pennypacker, 
and G. B. Durham 375 
