1903] VEGETATION OF THE BAY OF FUNDY MARSHES 285 
tion above, and it would be only when the minerals from the 
entire depth are exhausted that the fertility would begin to fail. 
A corollary of this would be that those marshes whose fertility 
is most lasting are the deepest, and those soonest exhausted are 
the shallowest, which certainly agrees in general with the actual 
facts,as observed and related by those familiar with the marshes. 
It is possible that the bogs, which in places underlie the 
marshes, play some part in this question of water conditions, but 
we have no facts bearing on this question. As already men- 
ticned, the borings made in the Aulac marsh showed twenty feet 
of bog lying beneath the eighty feet of marsh mud. Mr. Chal- 
mers is of the opinion that bogs extend practically everywhere 
beneath the marsh, but I do not think this is probable. If the 
mode of formation of the marshes in the earlier stages, given 
earlier in this paper, is correct, it is plain that the marsh could 
have formed without covering any bog except that which may 
have existed in the fresh-water lake in this basin before marsh- 
formation began. Bogs, however, could be buried under mud 
through natural changes in the courses of the rivers, and they 
are now often buried in the operations of bog-reclamation. Such 
places are said to be better drained and to bear larger crops than 
similar marsh not underlaid by bog. 
There are other physical properties of soil of much importance 
to the vegetation occupying it, such as its permeability to air, its 
power of absorbing and retaining heat, etc., but for the marsh 
mud no data at all are available upon these properties. 
We pass next to consider the chemical composition of the 
marsh soil, upon which some satisfactory data are available. 
Five samples carefully collected by myself in 1898 from differ- 
ent typical situations on the marshes, and of four of which the 
mechanical analyses have been given on an earlier page (281), 
have been carefully analyzed for me by the courtesy of Professor 
Frank T. Shutt, chief chemist at the Chemical Laboratory of the 
Dominion Experimental Farm at Ottawa, with the following 
results.27. To these are added an analysis made at the same lab- 
*7 A full discussion of these analyses by Professor Shutt may be found in the 
Report for 1901, cited in the Bibliography. 
