That this must be so will be admitted when it is remembered that each organ of a species is only maintained at its highest level because personal selection keeps ceaseless watch over it, and sets aside all the less favourable variations by eliminating the individuals which exhibit them. But this is no longer the case with a useless organ. When a weaker variant of a disused organ arises through the intra-germinal fluctuations of nutrition, this is transmitted to the descendants just as well as the normally developed organ, and in the course of generations will be inherited by a greater and greater number of individuals, and must ultimately be inherited by all in some degree or other. The objection has been urged from many sides that variations upwards would be quite as likely to arise as those downwards, but this is an error. Even if, at the beginning, the minus-variations were rarer than the plus-variations, in the course of generations the minus ones would preponderate because ascending variations of disused organs are not indifferent for the organism but injurious to it. Perhaps an increase in the size of the organ itself would do no harm, but in that of its determinant it certainly would, because an ascending determinant requires more nourishment than previously, and withdraws it from its surroundings, and thus from the determinants in its immediate neighbourhood; but these are those of functioning and indispensable parts. Individuals in whose germ-plasm the determinants of disused organs ascend, and thereby depress the determinants of organs which are still active, are subject to personal selection, and are eliminated. There thus remain only those with descending determinants; in other words, the chance of variants in the direction of weakness in useless determinants far outweighs that of variants in the direction of increased strength; the latter will soon cease to occur at all, for as soon as a determinant has fallen a little below its normal level, it finds itself upon an inclined plane, along which it glides very slowly but steadily downwards. This might be disputed if it could be maintained that, at every stage of the descent, a change of direction was possible. But this probably takes place rarely and only in the case of individual ids, and will therefore not be permanent because in general the stronger neighbour determinants will possess themselves of the superfluous nourishment, and a lasting ascent will thus be impossible to the weakened determinant. This is precisely what I have called Germinal Selection. The determinant whose assimilating power is weakened by ever so little is continually being robbed by its neighbours of a part of the nourishment which flows towards it, and must consequently become further weakened. As no more help will be given to it by natural selection, since the organ is no longer of any value to the species, the better among the weakened determinants