GERMINAL SELECTION 119 



direction of the variation in question is useful or prejudicial, or 

 on wliether the organ in question, the determinate, is of vahie or 

 otherwise. In this fact lies the great importance of this play of 

 forces within the germ-plasm, that it gives rise to variations (juite 

 independently of the relations of the organism to the external world. 

 In many cases, of course, personal selection intervenes, hut even tlien 

 it cannot directly effect the rising or falling of tlte Indivkliud 

 determinants — these are processes quite outside of its influence — hut 

 it can, Ijy eliminating the bearers of unfavourahly varying 

 determinants, set a limit to further advance in such directions. 

 This we shall consider in more detail later on. Personal selection 

 operates by removing unfavourably varying individuals frcmi the 

 genealogical tree of the species, but at the same time the determinants 

 which are varying unfavouraljly are also removed, and their variation 

 is thus put a stop to for all time. 



I have called these processes which are ceaselessly going on 

 within the germ-plasm, Germinal Selection, because they are 

 analogous to those processes of selection which we already know 

 in connexion with the larger vital units, cells, cell-groups and 

 persons. If the germ-j)lasm be a system of determinants, tlien 

 the same laws of struggle for existence in regard to food and 

 multiplication must hold sway among its parts which hold sway 

 between all systems of vital units — among the biophors which form 

 the protoplasm of the cell-body, among the cells of a tissue, among 

 the tissues of an organ, among the organs themselves, as well as 

 among the individuals of a species and between species which compete 

 with one another. 



If this be the case, we have here ready to hand the explanation of 

 every heritable variation of a part, ascending and descending alike. 

 Let us consider for a little the latter category — that is, the disappear- 

 ance of functionless or uteless ur(jant<. It is clear that, from tlie 

 moment in the life of a species that an organ, iV", becomes useless, 

 natural selection withdraws her hand from it ; individuals with better 

 or worse organs N are now equally capable of life and struggle, the 

 state of panmixia is entered upon, and the organ lY of necessity falls 

 somewhat below its previously attained degree of perfection. 



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 tlie 

 less favourable variations by eliminating the individuals which 

 exhibit them. But this is no longer tlie case w^ith a useless organ. 

 When a weaker variant of a disused organ arises through tlie intra- 



