Discovery reports (1962) Discovery reports discoveryreports30inst Year: 1962 -i- 0-5 mm. -J-0 tO-5 mm -1- 0 A b C Text-fig. 28. Physalia physalis. Three nectophores at different growth-stages. In A the gastrovascular space is wide open; in C occluded. A, xyo,B, x 29, C, x 53. radial canal, = muscular lamella. circular canal, = pedicular canal (occluded), = view nothing more than the irregular folding of these tissues at the point where the radial canals arise from the pedicel in the most advanced growth-stages that we know. It seems probable that th
Discovery reports (1962) Discovery reports discoveryreports30inst Year: 1962 -i- 0-5 mm. -J-0 tO-5 mm -1- 0 A b C Text-fig. 28. Physalia physalis. Three nectophores at different growth-stages. In A the gastrovascular space is wide open; in C occluded. A, xyo,B, x 29, C, x 53. radial canal, = muscular lamella. circular canal, = pedicular canal (occluded), = view nothing more than the irregular folding of these tissues at the point where the radial canals arise from the pedicel in the most advanced growth-stages that we know. It seems probable that the nectophores must function as swimming-bells. Judging by the undoubted breaking-loose of the terminal branchlets, consisting of terminal gonopalpon, nectophore and sexual medusoids, of Rhizophysa, I think it likely that the equivalent sections in Physalia may do the same thing. In Rhizophysa, nectophore and palpon are orientated in a peculiar way, axes in line, as if to balance each other when detached and swimming. In Physalia I have seen some very expanded gonodendra in which the stalk separating this part of the branch from the basal section—gonopalpon and jelly-polyp—is very fine. These terminal sections of the gono- dendra, when detached, are probably kept on the move by pulsations of the nectophores. It may be that the final branchlets become freed at some particular stage of growth, or at a certain season of the year, but I must say that I have seen no specimens in which the nectophores are missing from the normal position in which they first appear as very small buds very early in the development of the gonodendron. Palpons (Pis. XX, XXV) Besides the gonophores and nectophores, the final parts of the gonodendra in Physalia are made up of palpons (PL XX, fig. 4). The normal sub-terminal ones have at their base an asexual nectophore; the palpons of the terminal sections have at their base a jelly-polyp (' Gallertpolypoid' of Chun, a reduced nectophore). None of the p
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