CHAPTER VIII THE FORMS OF TISSUES OR CELL-AGGREGATES ( continued )

they must meet in a point; furthermore, they tend to do so at equal angles of 120ô¯, and there is an end of the matter. If we have four cells, then, as we have already seen, the conditions are satisfied by interposing a little intermediate wall, the two extremities of which constitute the meeting-points of three cells each, and the upper edge of which marks the 〜polar furrow.〝 Similarly, in the case of five cells, we require two little intermediate walls, and two polar furrows; and we soon arrive at the rule that, for n cells, we require nã€₤㈒ã€₤3 little longitudinal partitions (and corôÙreôÙsponôÙding polar furrows), connecting the triple junctions of the cells; and these little walls, like all the rest within the system, must be inclined to one another at angles of 120ô¯. Where we have only one such wall (as in the case of four cells), or only two (as in the case of five