An introduction to the study of seaweeds / by George Murray.

  • Murray, George (George Robert Milne), 1858-
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of seaweeds / by George Murray. Source: Wellcome Collection.

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    branches, constituting the antheridia, are often col- lected into groups covering portions of the surface of the thallus. The surface may be depressed where they occur, and sometimes even flask-shaped cavities are formed, recalling the spermogonia of lichens (Fig. 84). The actual male cell itself is quite colourless but always nucleated. When ripe it opens at the apex and the contents issue forth as a round pollinoid, some- times with a beak-like projection, and always with a nucleus. The occurrence of pollinoid cells in series, one above the other, in certain antheridia may be due to intercalary bipartitions, but possibly, on the other hand, to the successive abstriction of terminal cells which have remained attached in a chain. After the emission of the pollinoid, the supporting cell sometimes grows through and develops another male cell within the empty wall of the original male cell. No cilia have ever been detected on this mem- braneless pollinoid, though Schmitz and other ob- servers have rioted appearances that suggest the existence of some such organs. Guignard's recent observations, however, leave little doubt that the pollinoids are without cilia, and, moreover, that in some cases at least they are provided with a mem- brane at the time of their escape. So far as is known, however, they are wafted by the water much as the pollen grains of flowers are blown by the wind, and they do not usually become invested with a mem- brane until they reach the female organ. The carpogonium itself is a single cell drawn out at one end into a long fine hair called the trichogyne, which projects from the surface of the thallus, and