1918] CURRENT LITERATURE 285 
HITcHcock and CHASE” have published a manual of all the known grasses 
of the West Indian Islands. e term “West Indies” is defined as including 
Bermuda, the Bahamas, Trinidad, and Tobago, but excludes the Dutch Islands 
off the coast of Venezuela. The publication contains descriptions of 455 species, 
representing 110 sactige including 17 new species and a new genus (Saugelia) 
related to Gymnop 
STEPHANI*4 a sacad the fifth volume of his Species sl aia which 
deals with the Acrogynae, along with title page and index. He describes 296 
species, chiefly established by himself, representing 16 genera, 9 of a species 
being new. The large genera are Aneura (113 spp.) and Amthoceros (64 spp.). 
WERNHAM,*s in continuation of his studies of tropical American Rubiaceae, 
has described 7 new species of Psychotria. The same author* has described 
ro new species of Palicourea and 2 new species of Cephaélis from tropical 
America, chiefly Colombia.—J. M. C 
Sap concentration and plant communities.—Having developed a method 
of determining the osmotic pressure of cell sap by a depression of the freezing 
point, Harris” has proceeded to investigate the tissue fluids of plants typical 
of the deserts of Jamaica® and Arizona,” of the mesophytic vegetation of 
temperate regions, and of the rain forests of Jamaica. Aside from an interest- 
ing mass of data regarding the peculiarities of the cell sap of individual species, 
two generalizations stand out as important contributions to ecological science. 
They are to the effect that (1) there is a direct relationship between growth 
forms and sap concentration, as shown in the higher osmotic concentration of 
*s Hitcncock, A. S., and CuasE, AGNEs, Grasses of the West Indies. Contrib. 
US. Nat. Herb. 18:261-471. 1917. 
4 STEPHANI, F., Species Hepaticarum. Vol. V.  Acrogynae (pars quarta). 
Geneva. 1916. 
*s WERNHAM, H. F., Tropical American Rubiaceae. IX. Jour. Botany 55:251- 
254. IQ17. 
26 
, Tropical American Rubiaceae. IX. Jour. Botany 55:279-285. 1917. 
7 GorTNER, R. A., and Harris, J. ARTHUR, Notes on the technique of the deter- 
mination of the freeaing point of vegetable saps. Plant World 17:49-53. 1914. 
* Harris, J. ARTHUR, and LAWRENCE, J. V., Cryoscopic determinations on the 
— fluids a the plants of the Jamaican canta deserts. Bot. Gaz. 64: 285-305. 
ue J. ARTHUR, et me On the osmotic pressure of the juices of desert plants. 
Science N.S. 41:656-658. 1 
Harris, J. ARTHUR, and Livia. J. V., The cryoscopic constants of expressed 
vegetable saps as related to local cenditisns in the Arizona deserts. Physiol. 
Researches €S 221-49. 1916. 
* Harris, J. ARTHUR, and LawrENcE, J. V., The osmotic concentration of the 
tissue fluids of Jamaican montane rain forest vegetation: Amer. Jour. Bot. 4: 268-208. 
1917 
