In this manner the food absorbed by one individual contributes to the welfare of the whole colony, and the coenosarc has the 6 C FIG.
Thus a bract may be regarded, with Haeckel, as a modified umbrella of a medusa, a siphon as its manubrium, and a tentacle as representing a medusan tentacle shifted in attachment from the margin to the sub-umbrella; or a siphon may be compared with a polyp, of which the single tentacle has become shifted so as to be attached to the coenosarc and so on.
The result is a spreading or creeping colony, with the coenosarc in the form of a root-like horizontal network (fig.
The coenosarc may consist of a single elongated tube or stolon, forming the stem or axis of the cormus on which, usually, the appendages are arranged in groups termed cormidia; or it may take the form of a compact mass of ramifying, anastomosing tubes, in which case the cormus as a whole has a compact form and cormidia are not distinguishable.
The gonads (g) are produced on the manubrium, which has a hollow endodermal axis, termed the spadix (sp.), in open communication with the coenosarc of the polyp-colony and serving for the nutrition of the generative cells.
The coenosarc constitutes a system by which the digestive cavity of any one polyp is put into communication with that of any other individual either of the trophosome or gonosome.
The meshes of the basal network may become very small or virtually obliterated, so that the coenosarc becomes a crust of tubes tendingtofusetogether, and covered over by a common perisarc. Encrusting colonies of this kind are seen in Clava squamata (fig.
A typical Siphonophore is a stock or cormus consisting of a number of appendages placed in organic connexion with one another by means of a coenosarc. The coenosarc does not differ in structure from that already described in colonial Hydrozoa.