Average weight in grammes _W_/_L_^3 × 100 _W_/_L_^3 (smoothed) Jan. 2039 1·226 1·157 Feb. 1735 1·043 1·080 March 1616 0·971 0·989 April 1585 0·953 0·967 May 1624 0·976 0·985 June 1707 1·026 1·005 July 1686 1·013 1·037 August 1783 1·072 1·042 Sept. 1733 1·042 1·111 Oct. 2029 1·220 1·160 Nov. 2026 1·218 1·213 Dec. 1998 1·201 1·215 With unchanging length, the weight and therefore the bulk of the fish falls off from about November to March or April, and again between May or June and November the bulk and weight are gradually restored. The explanation is simple, and depends wholly on the process of spawning, and on the subsequent building up again of the tissues and the reproductive organs. It follows that, by this method, without ever seeing a fish spawn, and without ever dissecting one to see the state of its reproductive system, we can ascertain its spawning season, and determine the beginning and end thereof, with great accuracy. ―――――――――― As a final illustration of the rate of growth, and of unequal growth in various directions, I give the following table of data regarding the ox, extending over the first three years, or nearly so, of the animal’s life. The observed data are (1) the weight of the animal, month by month, (2) the length of the back, from the occiput to the root of the tail, and (3) the height to the withers. To these data I have added (1) the ratio of length to height, (2) the coefficient (_k_) expressing the ratio of weight to the cube of the length, and (3) a similar coefficient (_k′_) for the height of the animal. It will be seen that, while all these ratios tend to alter continuously, shewing that the animal’s form is steadily altering as it approaches maturity, the ratio between length and weight {102} changes comparatively little. The simple ratio between length and height increases considerably, as indeed we should expect; for we know that in all Ungulate animals the legs are remarkably _Relations between the Weight and certain Linear Dimensions of the Ox. (Data from Przibram, after Cornevin†.)_