Notes on Recent Literature. 
274 
from Sphagnum by Czapek. These authors give elaborate chemical 
data regarding the adsorption of bases and acids by these Sphagnum 
colloids from solutions of various salts, showing conclusively that 
they agree with other colloids in their behaviour, and that the 
properties of peat and humus are to be interpreted as colloid and 
adsorption phenomena according to the laws regulating the relations 
of colloids to other substances. It may be noted, however, that 
Baumann and Gully’s conclusions have been challenged by Tacke 
and Suchting (43) in a recent paper, in which the authors contend 
that there is insufficient evidence of the existence of special “ peat 
colloids ” or the non-existence of “ humic acids.” 
Among works devoted to Bryophyta, and more general 
publications, in which these plants are treated from the ecological 
point of view, mention may be made of recent papers by Macvicar 
(22), Grebe (11), Gyorffy (14), Spindler (40), Smith (39), Crampton 
(4), Rubel (32), Giesenhagen (9), and Sapehin (33). 
Of such publications, two may be selected for summarising 
here, on account of the comprehensive and detailed manner in which 
the authors have treated the ecology of Bryophyta. The best 
general account of the subject that has yet appeared in this country 
is Wheldon’s recent work (46), in which he describes a number of 
the more striking “ social moss groups,” e.g., those dominated by 
Rliacomitrium lanuginosum, Sphagnum, the “harpidioid” Hypnaceae, 
the interesting succession of bryophyte associations on sand-dunes, 
and the arctic-alpine Marsupella association. Schade (34), on the 
other hand, has published what may be described as the first result 
of the application of detailed or “ intensive ” ecological methods to 
the study of Bryophyta; that is to say, he has selected a relatively 
small area and made a minute and thorough study of the bryophytic 
flora and of the correlation between this and the various conditions 
ot the habitat, with exact observations and measurements of the 
physical factors. Schade deals with the bryophytic vegetation (with 
some references also to the lichens, fungi, and algae) of rock-surfaces 
in the mountains of Saxony; the phanerogamic plant-geography of 
this region has been already worked at by Drude (on whose 
suggestion Schade began his research) and other ecologists. Schade 
distinguishes three main types of habitat—moist, flooded, and dry 
rock-surfaces. To the moist ( bevgfeuclite ) type belong nearly all 
rocks with northern aspect; the surface is uniformly moist but not 
dripping. Such rocks show several distinct facies, the lowest, 
wettest, and most deeply shaded being characterised as the Pellia 
facies, with Pellia epiphylla as dominant form. Higher up comes 
the Conocephalus facies, with Conocephalus (Fegatella ) conicus 
dominant; other bryophytes, growing in the spaces between the 
thallus-branches of this liverwort, rarely produce sporogonia in this 
facies. Other facies in this moist type are characterised respectively 
by Calypogeia ( Kantia ) trichomanis, Diplophyllum albicans, 
Leptoscyphus Taylori, Rhahdoweisia fugax, Dicranella heteromalla 
and/), cerviculata, Tetraphispellucida ,and Odontoschisma denudatum ; 
while various lichens are dominant forms in other facies. The 
author describes the general conditions of each of these facies, 
with notes on the dominant and associate species in each. The 
cryptogamic vegetation of the dripping ( iiberrieselte) rocks shows 
three facies, characterised by diatoms, green algae, and the liverwort 
