Some observations on the structure and development of Volvox globator, and its relations to other unicellular plants / by Geo. Busk.

  • Busk, George, 1807-1886.
Date:
[1852]
Catalogue details

Licence: Public Domain Mark

Credit: Some observations on the structure and development of Volvox globator, and its relations to other unicellular plants / by Geo. Busk. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    distinct, uniform-sized, contiguous hexagonal masses. It con- tinues to grow, and very soon clear lines become apparent between the green masses, which arc thus very distinctly defined, retaining the same hexagonal form—each with an apparent nucleus, which is probably derived from the bright spherule contained in it, but as yet without brown spot, clear space (vacuole), or vibratile cilia. As the embryo continues to glow, the spaces between the green masses continue to in- crease ; the green bodies gradually lose the hexagonal form, and assume the appearance of the ciliated zoospore next to be described. Tliey are now about l-3000th of an inch, or thereabouts, in diameter, and the embryo, detached from its parent, becomes a free Volvox in its interior. We have thus arrived at the complete Volvox, and from the mode of its for- mation it is apparent that it consists of a transparent wall lined with the green bodies, and hollow in the interior; and also that it is surrounded, at all events while within the parent, with a delicate transparent areola, apparently of gela- tinous matter We have now to examine more minutely the structure and nature of the green gianules, and the further changes they undergo. Upon examination of the wall of a full-grown V. glohator with a sufficient magnifying power, it will be seen, upon view- ing the edges, as it were, of the image in the field, with the object so aiTanged as to bring the equatorial plane exactly into focus (fig. 5), that the green granules are, in fact, vesicular or semivesicular bodies of a flask-like or conical form, about l-3000th of an inch in transverse diameter, and placed at uniform distances apart. Each of them is prolonged out- wardly into a sort of peak or proboscis of a transparent and colourless or hyaline material, and from which proceed two very long vibratile cilia, which in close contact at first, pass through the parent cell-wall, upon the outer side of which they separate widely and perform very active movements. The outer cell-wall presents a minute infundibuliform depression at the point of exit of the cilia. It will also be observed, that each ciliated cell or zoospore, as it may analogically be termed, contains a green granular mass or masses, composed, for the most part probably, of chlorophyll granules and a more trans- parent body, which I suppose may be regarded as a nucleus, and derived, as it would appear, from one of the bright sphe- rules which have been noticed before. At an early period after the maturity or completion of the zoospores they exhibit a minute, circular, clear space, or sometimes, but I think rarely, more than one, which is worthy of very attentive considera- tion. This space is of pretty uniform size in all cases, and