Another well-known fact in natural history is, that the size of animals depends very much upon the fertility of the region they inhabit. Where food is abundant and nutritious, they increase in size in proportion to the quantity and quality; and this size, under the same circumstances, will run through generations, unless interrupted by artificial means. So, if the food is more difficult to obtain, and the pastures are short, the pliancy of the animal organization is such that it naturally becomes adapted to it, and the animal is of smaller size; and hence Mr. Cline observes that “the general mistake in crossing has arisen from an attempt to increase the size of a native race of animals, being a fruitless effort to counteract the laws of nature.” Mr. Cline also says, in his treatise “On the Form of Animals:” “Experience has proved that crossing has only succeeded in an eminent degree in those instances in which the females were larger than the usual proportion of females to males; and that it has generally failed when the males were disproportionally large. When the male is much larger than the female, the offspring is generally of an imperfect form; if the female be proportionally larger than the male, the offspring is generally of an improved form. For instance, if a well-formed large ram be put to ewes proportionally smaller, the lambs will not be so well shaped as their parents; but, if a small ram be put to larger ewes, the lambs will be of an improved form.” “The improvement depends on the principle that the power of the female to supply her offspring with nourishment is in proportion to her size, and to the power of nourishing herself from the excellence of her constitution; as larger animals eat more, the larger female may afford most nourishment to her young.”