the two.  It thus appears that warmth may be advantageous both as inducing early spawning in autumn, and an early entrance of fresh-run fish in winter; although a single river may not possess both attributes for the reason hinted at—­the deepest waters, though protected from winter’s cold, being also screened from summer’s heat.  Mr Scrope may therefore be regarded as right in his facts as to the earlier season of the upland streams, although his theoretical explanation of them is not conclusive.

The lateness of the spawning season in the Shin may, in some measure, be owing to the early breeding fish going up into the loch, from whence, after a time, they fall back upon the spawning places in the fords of the river.  The same thing happens in the lower regions of the Tay—­the fish fall back from the loch, and the ford between Taymouth Castle and Kenmore is by far the latest in that river.  Salmon have been seen to spawn there in February.  In regard to the general influence of the atmosphere, we may here remark that frosty weather is good for spawning; because the fish go then into the deeper or central portions of the fords, by which procedure the spawning beds are never dry,—­whereas, in time of spates, salmon are apt to deposit their spawn along the margins, and thus the roe is frequently destroyed by the subsiding of the waters.

However, the real importance of an early river has little or no connexion with the periods of the spawning process; because it is not so much the breeding fish that are of individual value in winter, as those which, having no intention or requirement to spawn until the following autumn, enter the fresh waters because they have already completed the days of their purification in the sea.  Although, when viewed in the relation of time, they may seem to form the continuous succession of spawning fish which have come up gravid from the ocean during the later months of autumn, they are in truth rather the avant-couriers of the newer and more highly-conditioned shoals which show themselves in early spring.  We believe that fresh-run fish may be found in all our larger rivers during every month throughout the year, though we cannot clear up their somewhat anomalous history, nor explain why the breeding season, as among land creatures of identical natures, should not take place more uniformly about the same time.  It is by no means improbable, however, that, as grilse seek our fresh waters at different periods from adult salmon, so salmon of a certain standing may observe different periods of migration from those of dissimilar age.