Text Fig. 2

Diagrammatic reconstruction of the soft parts (endoderm only) of a branch tip from serial sections. One polyp is shown with ectoderm and tentacles. Note the central and peripheral endodermal tubes anastomosing freely; endodermal "feet" of the polyps. The skeleton (black) is formed by placing flattened longitudinal fibres between peripheral endodermal tubes and joining them through the holes left by anastomosing tubes.