162 BOTANICAL GAZETTE [FEBRUARY 
analysis and the clearness of its presentation. The excellent illustrations 
accompanying the paper add not a little to its effectiveness.—R. A. EMERSON. 
Calcicoles.—M Atcoim WItson‘ has made a study of the varying composi- 
tion of the woodlands of southeastern England, in connection with variations 
in the substratum. His conclusions are in harmony with those of most English 
ecologists, namely that the flora of the chalk and of other calcareous strata 
differs considerably from that overlying non-calcareous strata. However, the 
vegetation on the siliceous London clay differs considerably from that on the 
very similar ‘‘clay with flints,’’ whereas the latter has a vegetation much like 
that of the chalk. Parallel species are found on the chalk and the clay with 
flints, the former being more xerophytic in structure; these results agree with 
those found long ago by KERNER. WILSON shows how other factors, such as 
depth of soil and amount of shade, are as likely to be limiting factors as is soil 
composition. These woodlands are largely coppiced every fourteen years or 
thereabouts, and WILSON pays large attention to the changes brought about 
at coppicing, through the admission of light, and to the gradual changes later 
on, as shade increasingly returns. While shade-tolerant species gradually 
get the upper hand in the years following coppicing, it is interesting to note 
that certain perennial species, usually regarded as light-requiring, may remain 
through the shade period; these plants are dwarf in habit and reproduce only 
vegetatively. 
s is well known, most American ecologists place little emphasis on the 
division of plants into calcicoles, silicicoles, etc. UTTERS,’ however, records 
Briti 
composed chiefly of fragments of granite and mica schist. The flora of these 
two moraines is strikingly different, only 34 of the entire 110 species occurring 
on both moraines; only 21 species occur somewhat equally in the two habitats. 
The flora of the limestone moraine is composed of species that are largely rare 
. or local in the Selkirks, and it is to be noted also that limestones are similarly 
infrequent in these mountains. All other limiting factors seem excluded except 
at of difference in chemical composition of the substratum.. There are 34 
species on these moraines, which were found in eastern North America by 
FERNALD;$ 20 of these have exactly the same type of soil distribution in these 
widely separated regions, and in no case is there a reversal of soil preference. 
6 Witson, Matcorm, Plant distribution in the woods of northeast Kent. I. 
Ann, . 25:857-902. figs. 4. pls. 3. I9II. 
7 Butters, F. K., Some peculiar cases of plant distribution in the Selkirk Moun- 
tains, British Cokie: Minn. Bot. Studies 3 and 4:313-331. jig. I- 1914. 
8 See Bor. Gaz. 45:138-139. 1908. 
