Observations on the spontaneous motions of the ova of the campanuloria dichotoma, gorgonia verrucosa, caryophyllea calycularis, spongia panicea, sp. papillaris, cristata, tomentosa, and plumularia falcata / by Robert E. Grant.

Date:
[1826]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the spontaneous motions of the ova of the campanuloria dichotoma, gorgonia verrucosa, caryophyllea calycularis, spongia panicea, sp. papillaris, cristata, tomentosa, and plumularia falcata / by Robert E. Grant. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    varied my experiments in every possible manner, I consider the spontaneous motions of the ova in the above species as suffi- ciently established by direct observation, and by the analogy of other zoophytes. The observations which I have lately made on the ova of the Plumularia Jalcata Lam., have not been less satisfactory than those so often repeated on the ova of the sponge. I have taken the mature ova from the vesicles of the plumularia, and examined their spontaneous motions, under the microscope, in the presence of experienced naturalists; and I now present to the Wernerian Society eight of these ova growing and branching on the side of a glass vessel, after their having remained three weeks in that situation. This species is very common in the deeper parts of the Frith of Forth ; its vesicles are very numerous, and its ova are in full maturity at the beginning of May. The ova are large, of a light brown colour, semi-opaque, nearly spherical, composed of minute transparent granules, ciliated on the surface, and distinctly irritable. There are only two ova in each vesicle; so that they do not require any external capsules, like those of the campanularia, to allow them sufficient space to come to ma- turity. On placing an entire vesicle, with its two ova, under the microscope, we perceive, through the transparent sides, the ciliae vibrating on the surface of the contained ova, and the cur- rents produced in the fluid within by their motion. When we open the vesicle with two needles, in a drop of sea-water, the ova glide to and fro through the water, at first slowly, but afterwards more quickly, and their ciliae propel them with the same part always forward. They are highly irritable, and frequently con- tract their bodies so as to exhibit those singular changes of form spoken of by Cavolini. These contractions are particularly ob- served when they come in contact with a hair, a filament of con- ferva, a grain of sand, or any minute object; and they are like- wise frequent and remarkable at the time when the ovum is bu- sied in attaching its body permanently to the surface of the glass. After they have fixed, they become flat and circular, and the more opaque parts of the ova assume a radiated appearance ; so that they now appear, even to the naked eye, like so many mi- nute grey coloured stars, having the interstices between the rays filled with a colourless transparent matter, which seems to harden