Heterogony and the Chemical Ground-Plan of Animal Growth

Abstract

IN 1924 in this journal, Huxley¹ first considered the relation between the growth of parts in a living organism, when the parts increase or decrease in relative size. The equation log y = log b + k log x describes the process, where y is the size of the part, x the size of the whole, and b and k are constants (the former giving the fraction of x which y occupies when x is unity, and the latter the ratio of the growth-rate of the part to the growth-rate of the whole). Thus on a double logarithmic grid, straight lines are obtained, the slope of which is determined by the constant k, and the absolute position of which relative to the axis values, by the constant b. Since Huxley's first paper, this simple relation has been abundantly verified for morphological magnitudes in a large number of animals, vertebrate and invertebrate, as described in his recent book.²