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‘To obtain animals with large lungs, crossing is the most expeditious method; because well formed females may be se- lected from a variety of a large size, to be put to a well formed male of a variety that is rather smaller—By such a method of crossing, the lungs and heart become proportionally larger, in consequence of a peculiarity in the circulation of the foetus, which causes a larger proportion of the blood, under such circumstances, to be distributed to the lungs than to the other parts of the body: and, as the shape and size of the chest, depend upon that of the lungs, hence arises the remarkably large chest, which is produced by crossing with females that are larger than the males.

‘ The practice according to this princi- ple of improvement, however, ought to be limited:, for, it may be carried to such an extent, that the bulk of the body might be so disproportioned to the size of the limbs as to prevent the animal from moving with sufficient facility—In animals, where ac-

_ tivity is required, this practice should not