Vegetation of Northern Cape Breton. 455 



firm. Weber's explanation of the manner in which these ponds 

 usually arise is somewhat as follows. They originate in the pools 

 of water which collect in the deeper hollows between the hum- 

 mocks on the surface, during wet seasons. During the dry 

 season the water collects here only temporarily, but long enough 

 to permit the existence of a number of low algae. The develop- 

 ment of algae has a detrimental effect on the growth of any 

 sphagnums which may be present, since {op. cit. p. 28) when the 

 water dries up they form a thin parchment-like coat which over- 

 grows the sphagnums and cuts off their light supply. When, in 

 times of increased precipitation, the hollows fill up with water, 

 wave activity brings about the enlargement of the basin, while by 

 its mere weight, which in general is greater than that of an 

 equal volume of water-soaked peat, the water contained in the 

 basin causes the pond to deepen, an end which is also favored 

 through the increasingly active circulation of oxygen through 

 the water. He further remarks that while during subsequent 

 dry periods numerous pools become overgrown again, in other 

 cases the pools persist and become deeper as the surrounding 

 surface of the bog rises higher. He consequently regards the 

 deepest pools, in general, as the oldest ones. 



Broadly speaking, \\'eber's explanation as to the origin of 

 these ponds roughly approximates that arrived at independently 

 by the writer. The essential points of both views are (i) the 

 subsequent, rather than antecedent, origin of the ponds with 

 reference to the bog; {2) the meteoric, rather than telluric, 

 source of the water supply. The chief point of difference is this. 

 According to the author's explanation, the ponds originate at a 

 rather early stage in the bog's history and by their presence 

 exercise an important influence on its development. Moreover, 

 after their preliminary period of growth, there is little if any 

 subsequent enlargement, but rather the tendency is just the 

 reverse. According to Weber's explanation, the ponds may 

 originate even on the surface of the mature bog. Moreover 

 they are constantly tending to increase in size. So far as the 

 raised bogs of northern Cape Breton are concerned, it is the 

 opinion of the author that the majority of the ponds to be found 

 on mature raised bogs have had a history essentially similar to 

 what he has described. But it also seems very likely that some 

 and quite possible that many of them may have originated in 

 the manner suggested by Weber. At any rate, the writer agrees 



