i 
IV TABLE OF CONTENTS 
The vertical distribution of Volvox in the plankton of Lake 
Monona Gilbert Morgan Smith 178 
A comparison of salt requirements for young and for mature 
buckwheat plants in water cultures and sand cultures 
John W. Shive and William H. Martin 186 
Cell measurement as an aid in the analysis of quantitative 
variation (with two text figures) 
WiLBER BrOTHERTON, Jr., AND H. H. BaRTLETT I92 
Respiration and catalase activity in sweet corn (with one text 
figure) Charles O. Appleman 207 
Some new species of Inocybe. George F. Atkinson 210 
No. 5, May 
The geographic affinities of the vascular floras of New England, 
the Maritime Provinces and Newfoundland (with plates 
XII-XIV) M. L. Fernald 219 
The contrast in the floras of eastern and western Newfoundland 
(with plates XV-XVII) M. L. Fernald 237 
Generic types with reference to the grasses of the United States 
A. S. Hitchcock 248 
Axillary cleistogenes in some American grasses (with five text 
figures) Agnes Chase 254 
Cyrtandreae Hawaiienses, Sect. Crotonocalyces Hillebr. (with 
plates XVIII-XXIII) Joseph F. Rock 259 
No. 6, June 
Breeding for disease resistance in plants W. A. Orton 279 
Behavior of plants in unventilated chambers 
F. C. Newcombe and Etta A. Bowerman 284 
Segregation of susceptibility to parasitism in maize 
Donald F. Jones 295 
The value of certain nutritive elements in the development of 
the oat plant (with five text figures) . .James Geere Dickson 301 
Uredinales of Guatemala based on collections by E. W. D. Holway. 
I. Introduction, Coleosporiaceae and Uredinaceae 
J. C. Arthur 325 
No. 7, July 
A new three-salt nutrient solution for plant cultures 
B. E. Livingston and W. E. Tottingham 337 
