222 
Two Recent Ecological Papers. 
seasons of the year. This association is distinguished by the author 
as a meso-pteridetum. In the xero-pteridetum of the drier woods, 
however, the association is not complementary, the Bracken 
rhizomes competing with Ling and Bilberry, and here sometimes 
one and sometimes another species is dominant. 
A good sketch of the general zonation of vegetation on the eastern 
slopes of the southern Pennines is given.—Moss-moor, Pteris-slopes, 
heather-moor, woods with xero-pteridetum, woods with meso- 
pteridetum, woods without Pteris. The zonation is determined 
partly by soil, partly by exposure and rainfall. 
The second part of the paper is devoted to a consideration of 
the effect of environment on structure in the case of some of the more 
wide-ranging and plastic species, such as Pteris nquilina , Scilla 
festalis, Deschampsia jlexuosa, Helens mollis, Vdccinium Myrtillus, 
etc. Very striking results are obtained, though on lines for the 
most part already well-known. The general result is that the more 
plastic species, both among the xerophytes and among the mesophytes, 
invade each others’ regions to a considerable extent, and in doing 
so become adapted often very extensively to the altered conditions. 
Dr. Woodhcad’s papef is illustrated by a good set of drawings 
of sections illustrating plasticity of structure as well as by several 
maps, showing the distribution of some of the principal types 
of vegetation, soil, etc. These maps, however, lose a great deal of 
their value from faults of reproduction, in the first place far too great 
reduction of scale, and also to some extent bad printing ; some 
of them are in parts unintelligible. It is not creditable to the 
Linnean Society to fail so badly in the illustration of its Journal. 
In comparing the two papers under review we see that the 
American excels by its wealth of exact physical factor and vegetation 
records, arranged according to a precise system, while the English 
has concentrated on particular problems. Both present interesting 
and valuable data, but a combination of the two methods might be 
expected to lead to more fundamental results. We are glad to 
learn that Dr. Woodhead is now at work on further study in the 
direction of exact physical factor determinations, and continuous 
seasonal observations, and we look forward to his further results 
with much interest. Ecology, served according to the highest 
ideals, is an exacting mistress, but her serious votaries may 
well feel that they are engaged on work which will form one of 
the most important parts of the future development of Botany. 
A. G. T. 
R. Madley, Printer, 151, Whitfield Street, Fitzroy Square, W, 
