Scheme 1. =Illustrating the theory of Pangenesis.= Here the germ-cell (a) develops into the body-cells, e, e, e, e, of animal I, as indicated by the oblique arrows, but not into any germ-cells, as indicated by absence of arrow between germ-cell (a) and germ-cells (b). The germ-cells (b) in animal I are formed by the aggregation of infinite numbers of gemmules from the various groups of body-cells, e, e, e, e, as indicated by the perpendicular arrows. The germ-cell (a) transmits germinal heritages to the body-cells e, e, e, e; these body-cells transmit the heritages to the germ-cells (b) by means of the gemmules. If the body-cells are modified in any way, correspondingly modified gemmules are sent to the germ-cells (b), and these germ-cells are modified and thus transmit acquired characters to animal II, and so on. [Illustration: I —> Skeletal-cells (e) (a) Germ-cell —> Glandular-cells (e) —> Muscle-cells (e) —> Nerve-cells (e) | | | | | | | | II | | | | | | | | —> Skeletal-cells (f) v v v v —> Glandular-cells (f) (b) Germ-cell —> Muscle-cells (f) —> Nerve-cells (f) | | | | | | | | III | | | | —> Skeletal-cells (g) v v v v —> Glandular-cells (g) (c) Germ-cell —> Muscle-cells (g) —> Nerve-cells (g) | | | | | | | | v v v v (d) Germ-cell. ] Scheme 2. =Illustrating the theory of Continuity of the Germ-Cells; pure germinal inheritance; and the non-transmissibility of acquired characters. The germ-cells are insulated from the body cells.= The germ-cell (a) develops into the body-cells, e, e, e, e, and the germ-cells (b), in animal I. The body-cells, e, e, e, e, do not influence in any way the germ-cells (b), as indicated by the absence of perpendicular arrows. The germ-cells (b) get all their heritages from the antecedent germ-cell (a), as indicated by the oblique arrow from (a) to (b). All heritages are purely through the germ-cells. The same with the animals II and III. Germ-cells (a), (b), (c), (d), are connected together by obliquely placed arrows, indicating the continuity of the germ-cells. [Illustration: I