. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 3g4 DISCOVERY REPORTS Thin strips of ectoderm are hard to obtain because of the deep folding of the layer. It would be of great interest to obtain histological data about the nerves in these regions, because Parker's finding of a high conduction rate (120 at 260 C.) makes it probable that the neurons would show a longitudinal orientation as they do in the mesenteries of Calliactis (Pantin, 1952).. glen, -* elenteron gl 50,u Text-fig. 3. Transverse section through adjacent portions
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. 3g4 DISCOVERY REPORTS Thin strips of ectoderm are hard to obtain because of the deep folding of the layer. It would be of great interest to obtain histological data about the nerves in these regions, because Parker's finding of a high conduction rate (120 at 260 C.) makes it probable that the neurons would show a longitudinal orientation as they do in the mesenteries of Calliactis (Pantin, 1952).. glen, -* elenteron gl 50,u Text-fig. 3. Transverse section through adjacent portions of the codon (C) and saccus (S). br = bridge cell, c1 = cuticle of codon, c- = pneumatocyst, = ectodermal gland cell, = root-like cuticular body believed to represent site of extinct gland cell, = similar body attaching pneumatocyst, = endodermal gland cell opening into the coelenteron, mes = mesogloea, , = muscle fibres of ectoderm and endoderm respectively, netn = nematocyst, \n = tetraploid nucleus, = nerve-cell with sense hair. An examination of the sexual medusoids (gonophores) from formol-fixed 'Discovery' material revealed the presence of nerves in the ectoderm of both ex- and subumbrellar surfaces. These nerves have been overlooked by previous workers using the sectioning technique (for example Steche, 1907). In the present investigation, they were studied in strips of tissue peeled off from the mesogloea, and stained in Hansen's trioxyhaematein. The nerve-cells are distributed sparsely but evenly. A point of interest is that there is no differentiation of the plexus into marginal nerve-rings. In medusae and swimming-bells where rhythmic pulsations take place, two marginal nerve-rings, one subumbrellar and one exumbrellar, are found in the ectoderm at the base of the velum. In Physalia the development of the gonophore is halted in the stage known as 'eumedusoid' (Hyman, 1940); the gonophore probably has no capacity for movement, j
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