CATTLE AND THE FOREST. 
325 
as supports for the vine, it is often very advantageous. The 
willows, and many other trees, bear polling for a long series 
of years without apparent diminution of growth of branches, 
and though certainly a polled, or, to use an old English word, 
a doddered tree, is in general a melancholy object, yet it must 
be admitted that the aspect of some species—the American 
locust, Robinia pseudacacia , for instance—when young, is 
improved by this process.* 
I have spoken of the needs of agriculture as a principal 
cause of the destruction of the forest, and of domestic cattle as 
particularly injurious to the growth of young trees. But these 
animals affect the forest, indirectly, in a still more important 
way, because the extent of cleared ground required for agri¬ 
cultural use depends very much on the number and kinds of 
the cattle bred. We have seen, in a former chapter, that, in 
the United States, the domestic quadrupeds amount to more 
than a hundred millions, or three times the number of the 
human population of the Union. In many of the Western 
States, the swine subsist more or less on acorns, nuts, and 
other products of the woods, and the prairies, or natural mead¬ 
ows of the Mississippi valley, yield a large amount of food for 
beast, as well as for man. With these exceptions, all this vast 
army of quadrupeds is fed wholly on grass, grain, pulse, and 
roots grown on soil reclaimed from the forest by European 
settlers. It is true that the flesh of domestic quadrupeds 
enters very largely into the aliment of the American people, 
and greatly reduces the quantity of vegetable nutriment which 
they would otherwise consume, so that a smaller amount of 
agricultural product is required for immediate human food, 
and, of course, a smaller extent of cleared land is needed for 
the growth of that product, than if no domestic animals ex¬ 
isted. But the flesh of the horse, the ass, and the mule is not 
* When vigorous young locusts, of two or three inches in diameter, are 
polled, they throw out a great number of very thick-leaved shoots, which 
arrange themselves in a globular head, so unlike the natural crown of the 
acacia, that persons familiar only with the untrained tree often take them 
for a different species. 
