This section is from the book "General Outline Of The Organization Of The Animal Kingdom, And Manual Of Comparative Anatomy", by Thomas Rymer Jones. Also available from Amazon: A General Outline of the Animal Kingdom and Manual of Comparative Anatomy.
* Milne-Edwards, Ann. des Sci. Nat. torn, xvi., 1841.
(315). The vascular apparatus above described is filled with a fluid in constant circulation, in which may be perceived innumerable round colourless globules. The course of the current is directed from the inferior vascular ring through the eight superficial canals situated beneath the ciliated ribs towards the summit of the body, whence it subsequently descends in a contrary direction through the two deep-seated trunks above described into the annular vessel, thus completing the circulatory round. The movement of the circulating fluid is tolerably rapid; nevertheless no traces appear of any central organ of impulsion, neither do the vessels exhibit the slightest contractility; in some of the larger trunks, however, the presence of cilia is distinctly perceptible, by the agency of which the circulatory current is produced.
(316). From the researches of Milne-Edwards, it appears that the vascular system of the Beroeform Acalephs communicates with the exterior by means of emunctory canals analogous to the anal tubes situated on the margin of the disk in Medusa aurita, described above.
In Beroe Forskahlii, Milne-Edwards was enabled to assure himself of the existence of two such outlets, situated not at the inferior margin of the body, as in other Acalephs, but at its upper extremity. When this portion of the animal is fully extended, it frequently occurs that a little ampulla suddenly makes its appearance on one side or the other of the terminal fossa, which, quickly increasing in size, exhibits in its interior movements of rapid rotation; then, suddenly opening at its summit, it discharges its contents and immediately disappears, leaving no traces of its excretory functions except a minute pore, which is easily distinguishable. These excretory ampullae communicate with the gastric cavity that forms the central reservoir of the vascular apparatus, and are evidently emunctories through which feculent matters are expelled.
(317). The body of the Beroes has generally been described as having the form of a bag open at both ends, - a mistake which is explicable from the circumstance that, when the animal is not completely unfolded, its superior extremity is retracted and puckered up in such a manner as to give the appearance of a wide orifice placed opposite to that which occupies the inferior extremity: this appearance, however, is deceptive; for if one of these Acalephs is carefully examined while swimming freely in its native element, it becomes evident that the supposed upper orifice is only a deep cavity the bottom of which is furnished with a delicate contractile arborescent fringe, in the centre of which is situated a little pyriform papilla, regarded as constituting an ocular apparatus.
(318). This oculiform speck, which is situated immediately in the axis of the body, presents, at its base, a globular spot of a red colour and granular appearance, in which are contained numerous minute crystalline corpuscles. The whole apparatus is immediately connected with a minute rounded mass, apparently of a ganglionic character, from which, in some genera, filaments are distinctly seen to issue.
(319). In Lesueuria, for example, on carefully examining the bottom of the wide excavation that exists at the anterior extremity of the egg-shaped animal, four mammillated processes are apparent, each occupying the median line of one of the four principal lobes; and in the midst of these is seen an oculiform tubercle, situated precisely in the axis of the body, which is remarkable for its bright red colour. It is of a spherical shape, and presents a granular surface similar to that of the brilliant red spots distributed around the margin of the disk in the Medusae, which Ehrenberg designates the eyes. Immediately beneath the oculiform spot is situated a subpyriform body, which is apparently of a ganglionic nature; its substance is more opake than that of the neighbouring tissues, and from it proceed a great number of filaments, apparently of a nervous character. These form four fasciculi, which run obliquely downwards towards the inferior and external margin of the principal lobes of the body: some very delicate filaments appear to terminate near the base of the accessory lobes; but the greater number are continued as far as the row of filiform appendages situated near the margins of the principal lobes, many of them apparently giving off ramifications in their course.
Moreover, besides the above, a small longitudinal filament may be traced along the middle of each of the ciliated zones, probably of a nervous character, and which give origin to a multitude of little filaments that are distributed in a very regular manner, in fasciculi, beneath each of the little transverse ridges whereupon the vibratile fringes are attached, as well as to the mid-spaces intervening between them: it would even seem that there is a little ganglion at the origin of each of these ciliary branches; but whether this be the case or not is doubtful. At the upper extremity of the body, the vertical or ciliary filaments are prolonged beyond the ciliated ridges, and becoming united in pairs, run towards the central ganglion situated beneath the oculiform spot, with which, in all probability, they communicate.
(320). From the above description it will be evident that the nervous system of Lesueuria differs widely in its arrangement from that supposed by Dr. Grant to exist in Cydippe*, resembling more the arrangement of the nerves in the Tunicated Mollusca, with which the Beroidaa present many natural affinities.
(321). The arrangement of the generative system in the Beroeform Acalephae is very imperfectly understood; or perhaps we ought rather to say that nothing is satisfactorily known concerning this part of their economy. M. Delle Chiaje* states that, upon the inner surface of each of the eight ciliated ribs, there is discoverable a longitudinal oviduct, to both sides of which are appended bunches of ovules, - an observation the accuracy of which is doubted by Milne-Edwards, who finds, indeed, on each side of the ciliated bands a multitude of little racemose bunches, of a rose colour, having the appearance of ovaria, but to whom it seemed that these bunches were contained in the substance of the walls of the body, and were simply dilatations of the lining membranes of the sub-ciliary vascular canals, which, instead of communicating with a common oviduct, opened into the vessels themselves.