ABSTRACT
Let us now ask,—What exactly in the inherited constitution of a creature is implied by an instinctive activity, such as that displayed in the building of a cell by the mud-wasp? It is clear that this inherited somewhat is by no means simple. It involves the potentiality of a number of distinguishable functions or capacities: first, the capacity to seek, to select and to gather up suitable pellets of clay; secondly, the capacity to carry them to a selected spot; thirdly, to pile them together (spreading each pellet neatly into a ribbon) to produce the cell of fairly definite size and shape; fourthly, to interrupt this activity in favour of a very different one (namely, that by which the egg and the spiders are deposited within the cell) and, thereafter, to complete the cell by closing its mouth.
