Anatomical and physiological observations on some zoophytes / by John Reid.

  • John Reid
Date:
[1845]
Catalogue details

Licence: Public Domain Mark

Credit: Anatomical and physiological observations on some zoophytes / by John Reid. 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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    cula, by tlie upward motion of which the eversion of this flexible tube is effected, are now seen lying within it. The third stage in the protrusion of the polype is the passage of the tentacula and pharynx through the upper aperture of the flexible tube. The greater part of this tube appears to be composed of setae connected together by a membrane. The polype has fifteen or sixteen tentacula. By breaking up a number of the cells I pro- cured two of the polypes nearly entire, and the stomach and its appendix had nearly the same relative size as in Crisia chelata. Several bodies, each composed of reddish brown cells inclosed in a membrane (ova), were seen among the broken- down cells. Flustra avicularis. This polype is thrown ashore in great quantities after storms, chiefly adhering to the roots of Flustra foliacea and F. truncata. The cells have almost always four hol- low spines, adhering to the upper margin of the cell, two to each angle. The two superior spines are pretty long and project up- wards and outwards, and the two inferior, which are placed close to the two superior at their origin, are considerably shorter and less thick, and project generally inwards, forwards and a little downwards. In a few cells I have seen five spines attached to the superior margin, three of these adhering to the outer angle. The bird-head processes attached to the outer edges of the branches of the polypidom are generally very considerably larger than those nearer their centres. Each bird-head process may be described as being composed of a body (fig. 12/), of a hinge- process (fig. 12 e), and of a pedicle (fig. 12 b). By the pedicle it is attached to the interior of a round hollow process projecting slightly from the anterior surface of the polypidom (fig. 12 a). The body of the bird-head process* is very convex along the lower edge, and it is elongated from below upwards and some- what flattened transversely. It is divided by an oblique ridge on its interior surface into two chambers (fig. 12 d), which com- municate freely at the superior and middle parts at least. The hinge-process is articulated to the superior or concave surface of the body by a hinge-joint, along the line of the superior termina- tion of the internal ridge which divides the body into two parts. The edges of the concave surface are thickened at this part, and present a slight depression on each, for receiving the two articular processes of the hinge-process. The body of the bird-head pro- cess is hollow, and its concave surface presents three apertures j the largest of these is the uppermost, and is separated from the middle by a bar stretched across between the articular cavities * In describing this moveable bird-head process, I have supposed the polypidom to be erect, and the concave surface of this process to be looking upwards in the direction ol the long axis ot the cells.
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