BY A. NORTON, M.L.A. 21 
in the same degree to the whole of that which had the white 
subsoil originally. It is most marked on the flats in the 
slate country, and these are the home of the peppermint. 
The Bergen-op-Zoom flats, where the trees first died in 
large numbers, are of this nature. Now the effect of sub- 
stituting this new surface, which is so largely mixed with 
pipeclay, for the former surface, whose chief ingredient was 
a poor kind of vegetable mould, would be to prevent the 
rain from penetrating very .quickly, because when dry it 
works, with trampling, into a very fine powder, and the 
particles uniting afterwards when moistened form a much 
more impermeable surface ; so that, when the rain falls only 
in occasional showers, this also contributes to deprive the 
roots of the trees of the proportion of moisture which they 
would have received had not the change of surface been 
effected. 
If my theory is well-founded, the peppermints would be 
the first to suffer, because they do not derive their chief 
sustenance from the subsoil: their roots spread from the 
base of the trunk and run along close to the surface, 
frequently appearing above it. When the moisture, that in 
ordinary seasons lies on the flats, has evaporated, they feel 
the want of it at once, and, in the absence of further rain, 
begin to lose their freshness, while trees whose roots pene- 
trate deeper are able to hold out longer; but all trees which 
are accustomed in normal seasons to almost unlimited 
moisture must soon begin to sicken when through any cause 
they are for long deprived of it. 
It is possible that when the trees of a forest have been 
weakened by a long drought in places where opossums exist 
in flocks as numerous as sheep, these opossums would eat 
off all the young shoots, which burst forth when seasonable 
rains have fallen; but not having yet seen them in such 
numbers, I find it difficult to speculate on a condition of 
things which so far surpasses my comprehension.* On 
New England, in some seasons, thousands of small beetles 
* In order, however, to see how important a factor in the destruction of 
forest trees these marsupials may be regarded by others, the reader is 
referred to the ingenious speculations made by the Rev. Peter Macpherson 
in his paper on ‘‘ Some Causes of the Decay of Australian Forests’’ (Proc. 
Roy. Soc. N.S.W., 1885. Vol. XIX., pp. 83-96). 
