372 BOTANICAL GAZETTE [april 



Nichols finds the bogs of the raised type, corresponding to the "Hoch- 

 moors" of Europe, occurring upon this continent in Newfoundland and those 

 parts of eastern Canada and Maine which are in close proximity with the sea 

 coast. The cUmatic factors necessary for their development are abundant 

 precipitation, relatively low atmospheric humidity, cool summers, and the 

 absence of extremely low temperatures such as prevail farther inland. One 

 of the necessary edaphic factors is an impervious substratum, here furnished 

 by the Laurentian rocks. This is vitally important, since the source of water 

 supply is the rainfall and not springs, as some have assumed. 



The early stages of these raised bogs are not essentially different from those 

 obtaining in bogs of the more common and familiar type, but their subsequent 

 development is dependent upon the presence of distinct types of Sphagnum. 

 Nichols classifies these mosses into 5 ecological groups, beginning with the 

 decidedly aquatic and ending with those of comparatively xerophytic habits. 

 It is upon the growth of the mesophytic and xerophytic sphagnums that the 

 developrtient of the dry raised bog depends. These mosses are cushion- 

 forming in habit, and their successive development elevates the central portions 

 of the bog many feet above its rim. Such a raised bog presents a hmnmocky 

 surface, and except in wet weather a rather firm springy substratum quite dry 

 underfoot. Upon the surface in addition to the xerophytic Sphagnum are other 

 mosses such as Racomitriiim and Polytrichum, some fruticose lichens, and 

 several ericaceous shrubs for the most part less than a foot high. Scattered and 

 dwarfed specimens of Larix and Picea mariana also occur. A typical specimen 

 of the former, scarcely a foot high, possessed a trunk i inch in diameter showing 

 more than 50 annual rings. 



Another striking feature of the region seems to be the development of sub- 

 sequent ponds within the bog area. These differ decidedly from the marginal 

 trenches described by Stallard,s which are due to fire consuming the peat 

 in the shallow marginal portions of the bog during periods of unusual drought. 

 The ponds in the Cape Breton bogs are due to the impervious nature of the peat 

 from some of the sphagnums forming barriers and dams which obstruct the 

 drainage on gentle slopes. Such ponds function as storage reservoirs, retaining 

 much of the water which accumulates in them during wet periods and thus 

 insuring to adjacent areas a constant supply throughout the season. 



The development of the raised bogs, the subsequent bog ponds, and other 

 features of the vegetation are illustrated by diagrams and photographs. The 

 various successions are carefully traced and clearly described, the various 

 communities being classified according to the system already noted.^ In its 

 comprehensive character, its abundance of detail, and its notable contributions 

 to various phases of ecology, including the relationships between deciduous and 

 coniferous forests, the ecology of the sphagnums and of the development of 



5 Stallard, Harvy, The origin of Sphagnum atolls. New Phytol. 15:250-256. 

 1918. 



6 BoT. Gaz. 66:385-388. 1918. 



