340 BOTANICAL GAZETTE [APRIL 
several applications of the theory of interest to ecologists and agriculturalists. 
These applications are of all the more interest because the efficiency of the 
soils has been shown” to be such that very considerable pressures may develop, 
which must be important factors in the upward movement of water in certain 
soils. It follows that whatever affects an increase in the concentration of the 
soil solution in the upper strata of such soils, whether it be the application of 
fertilizers or evaporation or the action of soil bacteria, aids materially in 
increasing the amount of water raised through the subsoil. Such factors may 
be involved in the increased water supply in climax mesophytic plant asso- 
ciations.—G,. D. FULLER. 
Liassic flora of Mexico.—WIELAND® has published a further study of the 
Liassic flora of Mixteca Alta, Mexico. The most significant botanical results 
were published in this journal.” The present contribution consists of a study 
of the composition of the flora largely for stratigraphical purposes. WIELAND 
shows that aggregates of species enable one to determine the age of a formation 
on the basis of the percentage of the major elements of the flora. He gives a 
table of the flora considered, with relationships to other floras that have been 
reported. The most conspicuous feature of this aggregate is the dominance 
of cycadophytes, which constitute 70 per cent of the flora. He gives illustra- 
tions of the overlapping of floras in the Jurassic. The suggestion of using the 
composition of a whole flora rather than certain species selected arbitrarily in 
the determination of strata seems to be a good one.—J. M 
The vegetation of Gothland.—THomas” has given an account of the 
vegetation of the Swedish island, Gothland. The island has an area of 1220 
square miles, about half of which has more or less ean vegetation. 
Some plants rare on the mainland, as the walnut and ivy, are common here. 
THOMAS, using the terminology of the English ecologists, is “a about half 
of the island was originally fenland (the term fen, by the way, should be 
adopted by American ecologists, as we have no good equivalent name for this 
very common formation); the vegetation aspect here and the constituent 
species are much as in the English fens. Calcareous bogs exist, compat rab 
to those of Northern England. Various successions terminating in forest cap 
be readily worked out, and the author appeals for an intensive study before 
virgin conditions are altogether gone—H. C. Cow Les. 
17 LynpE, C. J., and Durné, H. A., On osmosis in soils. Jour. Amer. Soc, Agron. 
5:102-106. 1913. 
8 WreLanp, G. R., The Liassic flora of the Mixteca Alta of Mexico; its composi- 
tion, age, and source. Am. Jour. Sci. 36:251-281. jigs. 2. 1913- 
%” Bot. GAz. 48:427-441. 1909. 
H. H., The vegetation of the island of Gothland. New Phytol 
10:260-270. pis. 2. 1911. 
