Collected scientific papers of Sir William Bate Hardy.

  • William Bate Hardy
Date:
1936
Catalogue details

Licence: In copyright

Credit: Collected scientific papers of Sir William Bate Hardy. Source: Wellcome Collection.

    20/978 (page 2)
    and gives origin to short processes by which it is attached to the under side of large stones. The perisarc of the foot is represented over the rest of the body by a delicate cuticle. Following on the foot is the middle region of the body, whence spring numerous blastostyles. Each of tlmse bears gonophores, male and female, on its proximal portion, while short capitate tentacles spring from the distal extremity. The blastostyles are without a mouth. The distal or oral region of the body of the hydranth is the longest, and is studded with very numerous, small, capitate tentacles to within a short distance from the mouth. The Early Stages in the Formation of the Gonophore and the Origin of the Sexual Elements The points noticed under this heading may be regarded as an addendum to KorotnefFs account of the development of the gonophore alluded to above. His brief and somewhat diagrammatic account is illustrated by figures which unfortunately show little attempt at histological detail. The structure of the ectoderm of the blastostyle. In each blastostyle two regions may be distinguished; a distal and shorter region bearing several small capitate tentacles, and a proximal region, on the whole free from tentacles, on which the gonophores are developed. The latter embraces two- thirds to four-fifths of the whole length of the blastostyle. The ectoderm of the distal portion resembles that of the body generally, with the exception that the muscle-fibres, which form its deepest layer, are not so strongly developed. Its structure is shown in PI. I, fig. 1. Like the ectoderm of the animal generally, it is covered superficially by a well-marked cuticle, which, when stripped off and examined with a high power, is seen to be divided into irregular areas, doubtless corresponding to the subjacent cell layer. This latter is composed of long columnar cells, tapering at their lower end. Each cell is about 25 /x long, though their dimensions possibly vary accord¬ ing as the whole blastostyle is in a condition of extension or contraction. Lying here and there between the pointed bases of these cells are scattered ganglion cells, which are connected with a rich plexus of nerve-fibrils situated in the deepest part of the ectoderm and immediately over the muscle-fibres. The latter run longitudinally, and immediately overlie the supporting lamella. Fibrils from the basal nerve plexus pass between the columnar cells towards the surface, and, in tangential sections, are seen to form a superficial plexus between the columnar cells. The same type of nucleus is found throughout the whole ectoderm. It is characterised by the presence of a distinct nucleolus linked by scattered fibrils with irregular patches of chromatin on their course to a deeply staining envelope.