CURRENT LITERATURE 
MINOR NOTICES 
North American flora.—The third part of Vol. 10 continues the presentation 
of the Agaricaceae by MurRILL,! the 12 genera of Pholiotanae being presented, , 
excepting the ae Inocybe. The 11 genera presented include 324 species, 
of which 76 are described as new. The largest genera are Gymnopilus (85 spp.), 
Naucoria (65 spp.), Hebeloma (50 spp.), Crepidotus (46 spp.), and Galerula 
(33 spp.). The remaining 45 species are distributed among 6 genera. New 
species are described in Crepidotus (7), Tubaria (4), Galerula (8), Naucoria (21), 
Pluteolus (4), Mycena (2), Gymnopilus (13), and Hebeloma (17).—J. M 
NOTES FOR STUDENTS 
Carbon assimilation JORGENSEN and SriLes? have summarized our 
knowledge of the processes involved in the assimilation of carbon by green 
plants and the pigments concetned in them. The portion dealing w:th the 
pigments themselves has been reviewed by Linx.3 In the introduction the 
reviewers express the hope that “the following pages will be of interest to those 
concerned in the development of scientific agriculture as well as to those inter- 
ested in plant physiology for its own sake.” The discussion of the path of 
gaseous exchange between the leaf and the surrounding atmosphere is based 
mainly on the work of BLACKMAN and Brown and EscomsBe. The conclusion 
reached is that the proof is now definite that the stomata are the main pat 
of the intake of carbon dioxide into the assimilating aerial leaf of the higher 
plants. Any intake that may occur through the cuticle is of very minor impor- 
tance. Carbon assimilation is regarded as a complex of processes which prob- 
ably obey quite different laws. Attention is called to the 5 obvious factors 
upon which the rate of carbon assimilation in the leaf may depend: (1) carbon 
dioxide supply, (2) intensity of illumination, (3) temperature, (4) water supply, 
(5) quantity of chlorophyll. To these is added BLaAcKMAN’s time factor. It is 
found that below 25°C. the rate of carbon assimilation a little more than 
doubles for each rise of 10° C. For cherry laurel this gives a van’t Hoff curve 
RILL, W. A., North American flora ro:part 3. pp. 145-226. Agaricales: 
Agaricaceae (pars), Agariceae (pars). New York Botanical Garden. 1917. 
2 JoRGENSEN, I., and Srites, W., Carbon assimilation. A review of recent 
work on the pigments of the green leaf and the processes connected with them. New 
Phytol. reprint no. 10. London. Wesley & Son. 1917. 
' 3 Bor. Gaz. 62:417-421. 1916. 
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