1906] CURRENT LITERATURE . 145 
having a peat substratum, dominated by Sphagnum, Cassandra, Andromeda, 
Oxycoccus, Ledum, Vaccinium, etc.—-a vegetation more nearly related flor- 
istically to the Hochmaor. Further, these occur in areas whose soil water is 
rich in mineral salts, frequently overlying marl! The raised bogs of America 
are strictly comparable to the Hochmoor of Europe, but their occurrence 
appears to be localized by climate rather than by the character of the soil 
r 
For both the flat and raised-bog plants, the authors conclude that the 
substratum is physiologically dry because of the combined influence of three 
factors: (1) high water-content of the substratum, (2) consequent low tempera- 
ture and (3) the difficulties in the way of root respiration (due to wet soil and 
scarcity of oxygen), accompanied by a general impairing of all root functions. 
The plants of the Flachmoor are noted for their ready absorption of 
mineral salts, absence of mycor ni unusual development of the — nd 
parts, and the high percentage of as cause of the xerophytic characters 
of many of the plants is not clea They a re probably connected with the 
difficulties of absorption. These at are hes hydrophilous, never occur- 
ring in dry situations. 
The Huchmoor plants, however, absorb mineral salts with difficulty; mycorhiza 
bas 
occurs in all the Ericaceae, in Empetrum, Betula, and Pinus; carnivorous plants 
are common; the root systems are poorly developed; and the ash content is 
low. The xesophyie character of the plants is in part due to the difficulties of 
absorption, and in part to their evergreen habit. Many raised-bog plants also 
occur in dry situations. 
The third and fourth chapters discuss the conditions and processes involved 
in peat accumulation, the chemical and physical properties of the end products, 
the classification of peats, the bog minerals, and the relation of bogs to coal 
deposits 
The geographic distribution of the bogs of Switzerland, a geomorphic classi- 
fication of the moors of the world, the relation of settlement to moor develop- 
ment, the economics of the Swiss moors (with bibliography), the bog deposits 
as records of the postglacial history of northern ngniariag form the other 
principal chapter headings of the first portion of the wo 
The second division gives a detailed description . the individual Swiss 
bogs. In most instances these include not only plant associations of the 
present surface but also the succession of plant remains occurring in the peat. 
The location of the bogs is made clear by-an excellent topographic map, upon 
which the distribution of the several bog types is shown. The bibliography 
occupies seventeen pages and includes only the more important purely scientific 
. Papers. 
e importance of the work from the standpoint of future investigation 
is undoubted. To American students it furnishes not only a key to the present 
status of the subject, but also a model for the study and description of our 
own bogs, marshes, and swamps.—E. N. TRANSEAU. 
