they rise to the utmost number that it will maintain; but if the number which it at first was stocked with be greater than it will carry, they will gradually sink down to that number. Again, if you plant a piece of ground with young trees much thicker than they ought to be, so many will die away after some years, that they will be reduced to that number which ought in the first instance to have been planted; the stronger plants, after a long contest, destroying the weaker. So that the increase in the number of animals of any particular species does not depend so much on the number of their young brought into existence, as on the degree of the support and sustenance they receive, after being brought into life, to preserve them and bring them to maturity. Hence, we certainly conclude, if the number of individuals of any species of animals do not increase in proportion to the number brought into life, that it is owing to the offspring of them not being properly sustained.
These facts obtain, with regard to the human race, in as full a manner as in the brute species, or in the class of vegetables.
We find that the inhabitants in few of the states of Europe have doubled in five hundred years. Hence there is a presumption that the people have not been well fed, or have wanted some other thing
