TABLE OF CONTENTS 
PAGE 
The morphology of Araucaria brasiliensis (with 
lates I-III - - - - eS 
. Lancelot Burlingame hx 
The archegonium of Sphagnum subsecundum. 
Contributions from the Hull Botanical Labo- 
ratory 199 (with plates IV-VII)_ - - . George S. Bryan 40 
Additional evidence of mutation in O6¢nothera 
(with seventeen figures) - - Harley Harris Bartlett 8&1 
he embryo sac and oS of Stiga lutea tac 
plates VIII and IX) Margaret R. Michell 124 
The origin of the inflorescences of Xanthium ae 
plate X) - Clifford H. Farr 136 
The visible effects of the Schumann rays on 
protoplasm - - W.T. Bovie 149 
Flower of Adenocaulon bicolor - (with fey XI and 
XII - es - - - - Jessie A. Ayres 154 
The coefficient of mutation in Oenothera biennis L. Hugo DeVries 169 
Growth studies in forest trees (with — XIII and ; 
XIV and two graphs) - - - H.P. Brown 1097 
Extreme alterations of cieweaned without injury 4 
(with four figures) - - W.J.V.Osterhout 242 
The alpine and subalpine vegetation of the Lake 
Tahoe region (with four figures) - . F.J. Smiley 265 
On the male gametophyte of Picea canadensis. 
Contributions from the Hull Botanical Labora- 
tory 200 (with plates XV-XIX and one figure) A. H. Hutchinson 287 
Studies in the genus Bidens. II. Contributions 
rom the Hull Botanical ee 201 
(with three figures) - Earl E. Sherff 301 
On the decrease of permeability due to certain 
bivalent kations (with eleven figures) - - W.J.V.Osterhout 317 
Branching in the Ophioglossaceae. Contributions 
from the Hull Botanical. Laboratory 202 — 
plates XX—XXI and six figures) - Loren C. Petry 345 
Variations in respiratory activity in relation to 
sunlight (with ten figures)  - - - H.A.Spoehr 366 
Vv 
