The silver fir is more exacting in the matter of climate than in that of soil. The great forest of the Vosges is chiefly on silicious ground; but that of the Jura, which is even finer, grows on limestone. The great silver firs at Rosneath, probably the oldest in the United Kingdom, stand near the sea level in deep sandy soil. They are certainly over 200 years old, the largest being about 110 feet high and 22 feet 7 inches in girth. These trees are very massive, and branch into great heads owing to their not having been grown under conditions of close forest. The only rival in bulk to them is to be found at Ardkinglass, on Loch Fyne, about 120 feet high, and estimated to contain over 1,000 cubic feet of timber. In many places on the south and east coasts the silver fir does not thrive. It requires an abundant rainfall and a moist atmosphere, which probably accounts for its inability to stand the climate of the Eastern United States. There are, however, some fine specimens in Sussex (at Cowdray there is, or was a few years ago, a silver fir over 130 feet high, with a clean bole of 90 feet), and at Alnwick, in Northumberland; but at Novar, so famous for coniferous trees, Sir Ronald Munro Ferguson has given up planting it owing to its inability to resist the attacks of aphis. This seems to indicate a constitution impaired by climatic influence, for insect parasites, though they certainly hasten the death of a weakly subject, are not likely to prevail over a thoroughly vigorous one. In Western Scotland, where, as in Ireland, the silver fir makes grand growth, aphides swarm immediately upon any tree that has been debilitated by late frost or other injury. On the other hand, the Caucasian silver fir (_Abies nordmanniana_), which thrives splendidly in many parts of Britain where the common silver cannot be grown, frequently succumbs in the west to the attacks of aphis. At Benmore, on the Holy Loch, about 2,000 acres were planted about forty years ago with different kinds of conifers. I have examined the lists of the species planted, and find that by far the largest proportion consisted of this Caucasian fir. The forest remains, a splendid monument to its designer's enterprise; but hardly a Caucasian fir is to be found in it. The prevailing species are Douglas fir and giant Thuja. Dr. Stewart M'Dougall has made some useful research, leading him to identify the silver fir aphis with _Chermes abietis_, the spruce louse which, as explained when treating of the larch, migrates to the larch and produces parthenogenic generations thereon. Dr. M'Dougall traces the silver fir louse to the same parentage. It follows from this that the spruce is a dangerous neighbour to silver firs.