1905] TRANSEAUBOGS OF THE HURON RIVER VALLEY 429 



species near the borders of the area of geographic distribution of 

 the bog plants, viz., climate. The bog plants of this vicinity come 

 into conflict with species whose range is either more nearly continental 

 or more southern. That the climatic and edaphic conditions of 

 this region are at present unfavorable to the successful competition 

 of the bog species with swamp species is evidenced wherever the bog 

 conditions have been disturbed. That the reverse is the rule in 

 eastern Canada has been shown by GANONG (18, p. 178). The 

 tenacity with which species, whose multiplication is principally 

 accomplished by vegetative means, hold an area under complete 

 control is apparent to any who have studied the vegetation of lake 

 shores. It is just as strongly marked in the case of the herbaceous 

 and shrubby bog vegetation. When we examine the chemical and 

 physical data, now at hand, concerning the soils occupied by bog 

 and swamp plants respectively, the conclusion must be that they are 

 wholly inadequate to account for the difference in vegetation. The 

 forester lays stress upon the fact that trees cannot gain a foothold 

 on areas now covered with a grass turf because of the difficulty of 

 the seedlings getting started. The bog societies form an equally 

 compact plant growth, and their preservation in this region would 

 seem to be dependent upon analogous factors. 



III. The bog-plant societies. 



The following descriptions of local bog areas occurring in the 

 Huron valley aim not only to present lists of plants found in this 

 vicinity, but to show their natural associations. The order in which 

 the areas are described corresponds to the relative amount of filling 

 which has occurred in the several basins. To a certain extent this 

 order is genetic, yet there can be little doubt but that many arctic 

 plants which were concerned in the pioneer stages of our mature bogs 

 are now extinct. If we accept the areas at West and First Sister 

 Lakes as representing bogs in youth, maturity may be illustrated by 

 the original vegetation of the bog on Carpenter's road. The Chelsea 

 area defines that stage beyond the climax, when the conditions 

 inaugurated by cutting, firing, and ditching have destroyed the 

 original tamarack forest, and in its place has come a rude mixture 

 of bog relicts and arborescent weeds. 



