Vegetation of Northern Cape Breton. 355 



of various deleterious substances, as well as on other peculiari- 

 ties of the substratum with which the character of the vege- 

 tation may be more directly correlated (in this connection, see 

 Rigg '16; also Harper '18, pp. 27-31). 



Drainage as a basis of classification. — In treating the lakes 

 and swamps of the inland group in northern Cape Breton, drain- 

 age has been selected as the most fundamental basis of classifi- 

 cation. On this basis the lakes and ponds have been divided 

 into two groups, well-drained and undrained, and the swamps 

 into three, well-drained, poorly drained, and undrained. The 

 practical application of any scheme of classification of course 

 has its limits, owing to the difficulty, if not the impossibility, of 

 adequately correlating cause and effect, and whatever factors 

 are selected as criteria, all sorts of intergrading conditions are 

 encountered. Particularly in the case of swamps is the com- 

 plexity of the situation enhanced in a cool, humid region such as 

 this by the fact that atmospheric factors may react on the vege- 

 tation in such a manner as to neutralize to a greater or less 

 degree the influence of dissimilar edaphic conditions. 



During the course of the present investigations in northern 

 Cape Breton, the writer has examined several hundred different 

 lakes and swamps. In a number of the swamps, in addition to 

 observations on the surface conditions, soundings were taken 

 with a fifteen foot iron rod (summer of 191 5). By this means 

 it was possible (/) to ascertain the depth of the underlying 

 vegetable deposit; (^) by the attachment of a Davis peat-sampler 

 (see Bastin & Davis '09, p. 61), to determine the character of the 

 deposit at different depths; and (3) with the aid of a hand-level, 

 to figure out the topography of the underlying terrain, with 

 particular reference to its bearing on the drainage problem and 

 also its general relation to the surface of the swamp. 



Well-drained and undrained swamps compared. — In their 

 typical development, well-drained and undrained swamps differ 

 from one another in several important respects. (i) Well- 

 drained swamps are best developed on springy slopes, where the 

 gradiant is sufficiently steep to insure adequate drainage. They 

 also commonly occur along the banks of streams (many such 

 swamps, more especially along small brooks, are better included 

 with the swamps of the inland group than with those of the 

 river group). Undrained swamps, as exemplified by bogs. 



