272 
Notes on Recent Literature. 
distinct species, that various species and even genera are clearly 
artificial and include “biological” forms of remote affinity, and so on. 
He lays stress on the importance of taking into consideration the 
biology and ecology as well as the morphology of the Musci, in 
order to arrive at something approaching a natural system of 
classification. Though Loeske does not put forward a new scheme 
of classification of the Musci, regarding this course as premature 
until further work has been done, his views in this matter agree 
closely with those of Fleischer and Lorch, which were followed by 
the present writer in his recent attempt to formulate a new 
classification of the Bryophyta. 1 
Lorch (21) has supplemented his fine monograph of the 
Polytrichaceae by a detailed paper on the structure and mechanism 
of the tissues concerned in the “ hygroscopic ” movements of the 
leaves in this family of mosses. 
Passing by various papers in which the spores, etc., of mosses 
were used as materials in physiological and cytological researches, 
there remain for mention several publications of interest concerning 
the biology of these plants and their adaptations to the varying 
conditions of their habitats. For instance, Schoenau (38) has 
investigated the methods of branching in mosses, with special 
reference to the influence of external conditions, and has demonstrated 
the marked influence of light and of moisture in particular upon the 
occurrence and form of branching; while Janzen (17), in an interesting 
paper which may be said to break new ground so far as bryophytes 
are concerned, has described the modes of branching and leaf- 
arrangement in various liverworts and mosses from the point of 
view of “ leaf mosaic ” adaptations. 
Irmscher (15) has investigated experimentally the resistance 
of cold and drought by mosses, and finds that while most of the 
species used showed great powers of resistance to continued desic¬ 
cation, they were readily injured by alternate desiccation and 
soaking at short intervals ; the dormant axillary buds are much 
more resistant to drought and cold than are the leaves ; and that 
mosses of the most diverse habitats show a striking uniformity in 
regard to cold resistance, though varying greatly in their resistance 
to desiccation. Grebe (12) has published an extremely interesting 
and well-arranged account of the various structural adaptations of 
xerophilous mosses. Such adaptations in the sporophyte (sporo- 
gonium) include absence or shortness of the seta, causing the 
capsule to be sessile or nearly so, and thus enveloped by the 
uppermost leaves of the gametophyte ; downward curvature of the 
seta, causing the young capsule to be plunged among the leaves— 
later, the seta becomes erect, to facilitate spore-dispersal by the 
censer-mechanism of the ripe capsule : the presence of a large or 
inflated calyptra which completely envelops the capsule, or of a hair- 
clad calyptra as in Polytrichaceae; sheltered position of the 
stomata, which occur in the grooves of the furrowed capsules of 
Orthotvichum , and in the annular depression between capsule and 
apophysis in Polytvichum, and so on. Xerophilous adaptations in 
the gametopyte include the common cushion-like habit of the 
plants ; hayaline hair-points on the leaves; leaves with broad midrib 
and narrow lamina; more or less completely rolled-up leaves ; 
New Phytologist, Vol. X (1911), pp. 29-43. 
1 
