TABLE OF CONTENTS 
V 
An apparatus for determining small amounts of carbon dioxide (with 
one text figure) R. C. Wright 368 
The secretion of invertase by plant roots (with one text figure) 
L. Knudson 371 
Daily rhythms of elongation and cell division in certain roots (with 
Plates XXIV and XXV) Ray C. Friesner 380 
No. 10, December 
The modification of vegetative and reproductive functions under some 
varying conditions of metabolism E. J. Kraus 409 
The cambium and its derivative tissues. III. A reconnaissance of cy to- 
logical phenomena in the cambium (with Plates XXVI-XXIX) 
■ I. W. Bailey 417 
Morphology and life history of some Ascomycetes with special reference 
to the presence and function of spermatia (with two text figures 
and Plate XXX) B. B. Higgins 435 
Biology, morphology, and cytoplasmic structure of Aleurodiscus (with 
Plates XXXI-XXXIII) H. E. Stork 445 
The germination of the spores of Conocephalum conicum (with 
Plates XXXIV-XXXV) Sister M. Ellen 458 
Index to Volume VII 465 
(Dates of publication: No. i, Feb. 25; No. 2, Mar. 10; No. 3, Apr. 17; 
No. 4, May 20; No. 5, June 16; No. 6, July 29; No. 7, Aug. 6; No. 8, Nov. 5; 
No. 9, Dec. 7; No. 10, Jan. 12.) 
