Scots fir), although of more rapid growth on the loam than on the sand; and the best Scots fir we have ever seen, of equal age and quickness of growth, is growing upon Carse land (clayey alluvium). The reason that Scots fir is of better quality, and more resinous, on good loam and moist till, than on poor siliceous ground, may probably be, that the loam contains more oleaginous matter, and other {304} vegetable products which bear a near relation to resinous, and which, transmitted upwards from the roots, may occasion richer assimilated juices. Men fed upon whale or seal blubber, if the digestion is good, have much fatty deposit upon the body, and the perspired fluid is oil. It is a fact well known to every intelligent farmer, that _infield_ or _croft_ land, that is land, which, having been earliest cultivated, was, of course, the best soil at first, and which has also been long highly manured at the cost of the _outfield_, and therefore containing much oleaginous and other matter, products of organization, produces grasses and other vegetables much more nutritive to cattle than the _outfield_, even though these vegetables be of the same species, and by reason of more careful culture of those of the _outfield_, also of the same size of plant. We have also considered that light, poor sandy soil, which throws up a considerable flush of vegetation in the spring, partly because it has then sufficient moisture, but which almost entirely gives over producing throughout the latter part of the summer, partly because the winter’s moisture is exhausted, may throw out the frame or skeleton of a considerable growth, or annual layer of wood, in the early part of the season, but may not afford sufficient matter for the filling up or {305} maturing the layer into good dense timber later in the season, when the assimilated fluid or sap is believed to descend.