Different modes and grades of selection--Changes due to the influences of environment--Superfluity and lack of food--The horses and cattle of the Falkland Islands--Angora animals--Protection against cold in Arctic and marine mammals--Plant-galls--Nägeli's _Hieracium_ experiments--Experiments with _Polyommatus phlæas_--Artificially produced _Vanessa_-aberrations--Vöchting's experiments on the influence of light in the production of flower-forms--Heliotropism and other tropisms--Primary and secondary reactions of organisms--Herbst's 'lithium larvæ'--Schmankewitsch's experiments with _Artemia_--Poulton's caterpillars with facultative colour adaptation--Colour-change in fishes, chamæleon, &c.--Actual scope of those influences which directly produce organic changes. Through a long series of lectures we have devoted our attention to those phenomena which bear some relation to the processes of selection; we have attempted to gain clearness in regard to the modes and stages of these, and we reached the result that all variations which have taken place in organisms since the first appearance of living matter are directed by processes of selection, that is, their direction and duration are determined by these processes, although they may have their roots in external influences. But it is not to be supposed that this guidance is due solely to that one kind of selection which, with Darwin and Wallace, we designate 'natural selection'; on the contrary, we must regard this as only one of the different modes of the processes of selection, necessarily occurring between all living units which are equivalent to one another, and which, therefore, must maintain a continual struggle with one another for space and food. If the expression 'natural selection' were not already so firmly fixed in its meaning, I should propose that it should be employed in the most general sense for all the processes of selection collectively, but we must keep to its original meaning and use it only for personal selection. We have seen that processes of selection take place even between the elements of the germ-plasm in all organisms which possess a germ-plasm as distinguished from the mass of the body, and that through these processes there arise those hereditary individual variations which, under some circumstances, form the basis of transformations in the species.