Vegetable and Animal 
dead vegetable matter improve the soil by their casts. 
This, then, can bear more grass which will enable a 
larger worm population to live. 
Living as we do in a country which is mostly good 
loam and never destitute of “soil,” it is not easy to 
realise how different is the state of an unfortunate vege- 
table doomed to languish in a purely “mineral” earth, 
where there is neither leaf mould nor dead organic 
matter. : 
In such open floras, the occasional visit of an animal 
will be extremely beneficial, even if it does devour half 
the year’s foliage. 
In the open floras of the Arctic regions, of scrubs 
and of dry tropical countries as well as in the peat- 
mosses of this country, this good influence of animals 
has been pointed out. Mr. Sewell has shown that an 
abundance of rich grasses and unusual plants char- 
acterises those islands in Lapland where the gulls 
breed and where guano is abundant. 
Middendorf has a graphic picture of the desolation 
and dried up appearance of the Arctic Tundra in 
Taimyrland, Here and there, in the monotony of its 
brownish-yellow surface, the eye discovers at once 
patches of a bright refreshing green. Such spots are 
invariably near the burrows of the Arctic fox, or where 
the Samoyeds have folded their reindeer.* 
So also in the dreary and dry scrub which covers the 
arid Patagonian tableland, vivid patches of green grass 
are found only at those places to which the guanaco 
habitually resorts. 
Something of the same kind is said to be visible in 
India where old sheep-folds or cattle pens may remain 
green when the ordinary open flora has withered to 
nothing. 
Even in Scotland, when walking over the dark-brown 
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