intention; it will give way in the attempt. In crossing there are several important things to be attended to. Well formed parents ought to be selected, and, if enlargement of the carcass be wanted, the issue should be better fed than its originators, which ought to be of a size rather under, than above what the pasture is capable of supporting. The size of the parents should not be much disproportioned at first, as nature abhors sudden extremes, and does every thing in the most gradual manner. It is better, when some increase has been attained, to bring the breed to the required size by one or two crossings.[15] In choosing a breed, we should adopt that which affords the greatest quantity of market produce, in return for the food consumed;[16] and a particular breed ought always to be preferred to the sheep of a district. We must not imagine, that when, by dint of crossing, we have obtained the variety wanted, that it will remain in the condition to which we have brought it, without the slightest liability to alter. Many farmers believe they have done all that is required, if they subject their stock to three or four crossings with a breed of acknowledged excellence. They think that the improved animals they have obtained will support their acquired characters, uninfluenced by extraneous agency. Now nothing can be more faulty than this mode of management, as is proved by a comparison of stock so treated, with flocks which have uninterruptedly received that undeviating attention, which can alone ensure a continuance of the properties desired. Such men forget, that the climate is operating with as great certainty on the animals as on the rocks around; and that as the herbage is determined by the nature of the adjacent rocks, so are the peculiarities of the sheep influenced by the herbage; and that if they manage to change the characters of the breed, it can, in a majority of cases, be only for a time, unless the tendencies of the surrounding elements are counteracted, by a constant recurrence to the originators of the flock. "I am sorry," says Little, in his valuable practical observations, "to say, that there are too many examples of those, who thought themselves at the head of improvement in stock, relaxing their exertions, and keeping by their own stock; and the consequence has been, that such stocks have degenerated, become delicate, tender, and diminutive in size; and from no other cause but that the same pains have not been taken to preserve the improvement, that was taken to effect it. I could mention many improvers who were of the first class formerly, but who are now only in the second." Changes, in fact, by crossing are not to be effected in a short space of time; you must look forward to several years of constant exertion, before you can hope, in this manner, to alter your stock.[17] Then, again, we must be aware of the tendency which nature, in numerous instances, displays to perpetuate diseases, dispositions,