endless which I could bring forward to aid my explanations; but these it would be needless to give, since it is in the power of every one to study the differences in form and features of the classes of society in our own island, and by so doing understand the influence of otherwise trivial and unimportant circumstances, on an animal at all times so easily moulded to situation as the sheep. (86.) _Varieties from mode of Breeding._--Changes are wrought for the most part by attention to the mode of propagation of the plant or animal, by the plan of crossing; and by careful selection of the parent stock. Every one must be struck with the varieties constantly occurring in the vegetable world: Flowers change their colours, and become double; and these characters can be perpetuated by seed. Hedge-row plants may be observed to vary even in the limits of an ordinary walk, and to be continued as varieties so long as they remain in the same locality. The following striking example of the extent to which plants may be made to vary by altering their circumstances, is related by Mr Herbert in the _Horticultural Transactions_, vol. iv:--"I raised from the natural seed of an umbel of a highly manured red cowslip, a primrose, a cowslip, oxlips of the usual and other colours, a black polyanthus, a hose-in-hose cowslip, and a natural primrose bearing its flower on a polyanthus stalk. From the seed of that very hose-in-hose cowslip, I have since raised a hose-in-hose primrose. I therefore consider all these to be only local varieties, depending upon soil and situation." "Fifty years ago," says Buffon (writing in 1749), "our pot-herbs consisted of a single species of succory, and two of lettuce, both very bad; but we have now more than fifty kinds of lettuce and succory, all of which are good. Our best fruits and nuts, which are so different from those formerly cultivated that they have no resemblance but in the name, must likewise be referred to a very modern date. In general, substances remain, and names change with times: but in this case names remain, and substances are changed. Our peaches, our apricots, our pears, are new productions with ancient names. To remove every doubt upon this subject, we have only to compare our flowers and fruits with the descriptions, or rather notices of them transmitted to us by the Greeks and Romans. All their flowers were single, and all their fruit-trees were wild stocks, and their species very ill-chosen. Their fruits of course, were small, dry, sour, and had neither the flavour nor the beauty of ours. These new and good species originally sprung from the wild kinds; but how many times have their seeds been sown before this happy effect was produced? It was only by sowing and rearing an infinite number of vegetables of the same species, that some individuals were recognized to bear better and more succulent fruit than others; and this first discovery, which supposes much care and observation, would have