« ElőzőTovább »
jelly. It then immediately proceeds to multiply itself in geometrical proportion by fissure until masses are formed, which, under favourable circumstances, attain a diameter of three or four inches, and consist of aggregations of many thousands of zooids. In this Protozoan the division is not complete; the zooids are united by fine threads, which permeate the gelatinous mass, and are homologous with the stalks of Epistylis. These threads also appear to have the property of transmitting nervous impressions through the whole mass of this compound animal, and rendering the movements of the associated zooids consentaneous.
When in England some years ago, I found in one of my fresh-water aquariums a great number of specimens of Stentor Mülleri, each one of which was surrounded at its base by a flocculent deposit similar in structure to the lorica of Ophrydium versatile, and into which the animal could withdraw itself. At first I considered that this state was the result of disease, but further experience showed that the deposit was never absent. Many of the animals inhabited a tall gelatinous pillar, by which they raised themselves considerably above the surface on which they grew (fig. 11). Others by fissure had formed colonies, which were attached to the glass, or hung downwards while floating on the surface of the water; others, again, were swimming naked in search of sites for future erections; but no fixed animals were found to be destitute of a lorica. I have repeatedly met with this animal since, and always in the same loricated state.
In the summer of 1857, a small species of Stentor, of a deep chestnut colour, occurred in the pond of the Edinburgh Botanical Gardens, which is in the habit of secreting a lorica like that of Stentor Mülleri. This species, which I have called castaneus, selects the tips of the shoots of Myriophyllum for its abode, and glues all the opening leaflets together with a mass of jelly, from which the zooids protrude their wheel-bearing heads. The possession of a lorica removes Stentores Mülleri and castaneus from the family Vorticellina to that of Ophrydina, which (says Ehrenberg) "includes true Vorticellæ or Stentors inclosed in a gelatinous membranous little box” or shell. In the last family, a new genus will
have to be formed for their reception, for which I propose the name of Salpistes, from ounaitis, a trumpeter.
Since the above was written, my friend Mr Alder has informed me that he has also discovered L. producta near Tynemouth.
III. Observations on British Zoophytes.-(1.) On the Reproduction of
Turris neglecta. (2.) On the Development of Hippocrene (Bougainvillea) Britannica (?) from Atractylis (Eudendrium) ramosa. (3.) On the Development of Hydra Tuba (Strobila) from Chrysaora. By T. STRETAILL Wright, M.D.
Description of Plate III. Fig. 1. Clavula Gossii, proles Turris neglectæ.
2. Hydra tuba (Strobila) in various stages. 3. Corallum of same.
1. On the Reproduction of Turris neglecta. The only observations that we have as to the reproduction of the gymnopthalmatous Medusæ are those of Mr Gosse with regard to Turris neglecta. He is the pioneer who first actually witnessed, or rather caught a glimpse of, the reproduction of a hydroid zoophyte from a recognised species of Medusa. In September 1852, he saw the oval purple gemmules of Turris neglecta escaping from the walls of the ovaries, and dropping down to the bottom of the vessel in which they were confined, where they moved slowly about by means of their vibratile cilia. He placed a number of these gemmules in a properly-constructed cell, and, by watching them, ascertained the following facts :-" The gemmule (says he) having adhered to the glass, grows out into a lengthened form, variously knotted and swollen, and frequently dividing into two branches, the whole adhering closely to the glass. After a day or two's growth in this manner, a perpendicular stem begins to shoot from some point of this creeping root, and soon separates into four straight, slender, slightly divergent tentacles, which shoot to a considerable length. The little creature is now a polyp of four tentacles.” At this stage they all died, and he never succeeded in repeating his observations. In August last, I picked up at Queensferry a spe
cimen of Turris neglecta laden with dark crimson ova. This prize I accommodated with a commodious apartment, in which it might exercise the duties of maternity. After a weary delay of nearly a fortnight, the young made their appearance as dark crimson ciliated larvæ. These underwent the changes 80 well described by Mr Gosse; but instead of being destroyed by starvation in their infancy, the four-armed polyps underwent a further development into a zoophyte resembling Clava repens (fig. 1, Plate III.) The young of Turris neglecta, which I now place on the table, and to which I have given the name of Clavula Gossii, may be described as follows:
Clavula Gossii (Proles Turris neglecto). Polypary creeping, sheathed in a chitinous polypidom. Polyps minute, seated on short stalks, spindle-shaped, furnished with about twelve tentacles ; upper row of tentacles long, filiform, four in number, erect; rest of tentacles scattered, shorter, inclined upwards ; colour crimson.
2. On the Development of Hippocrene (Bougainvillea) Britannica
from Atractylis (Eudendrium) ramosa. This paper appeared as a note to Dr Wright's paper on Atractylis on page 449, Vol I., of the Proceedings.
3. On the Development of Hydra tuba (Strobila) from Chrysaora.
In September last, I extracted a larger number of young from the reproductive sacs of Chrysaora. The young in their first stage are (as has been repeatedly observed) swimming ciliated larvæ. The greater part of these attached themselves to the surface of the water, and hung downwards as globular sacs seated on long thin pedicles or stalks (Plate III., fig. 2). The pedicles were surrounded by a thick and very transparent gelatinous case, corallum, or polypidom. The globular sac acquired a mouth, and afterwards four, eight, sixteen tentacles successively. As the Hydra grew, it produced additional attachments from its body. The bases of these attachments in the fully-developed Hydra appeared as a number of closely-aggregated circles (fig. 3), in which the four tissues, colletoderm (a), corallum (6), ectoderm (c), and
endoderm (d), could be distinctly made out in those specimens attached to surfaces of glass. It appears, from the above observations, that the Hydra tuba is not a naked polyp, as hitherto described.
IV. Specimens of the Lantern Fly of British Honduras were ex
hibited by J. A. Smith, M.D. These appeared to be the Fulgora laternaria, Linn., and were sent for exhibition by Mr James Banks, Preston pans. It seemed, Dr Smith said, to be still undecided among naturalists whether these flies were really luminous at times or not. Other luminous so-called fire-flies belonged to the class of beetles (Coleoptera). It was of importance, therefore, that the undoubted evidence of eye-witnesses should be produced ; and it was suggested that Mr Banks be invited to write to his correspondents in Honduras for information on the subject.
V. Notes of Fossils from the Old Red Sandstone of the South of Scot
land. By John Alex. Smith, M.D. A specimen of a fossil plant was exhibited from the Upper Old Red Sandstone of Roxburghshire. It was found last autumn in the Denholm Hill quarry, in the white rock of its upper beds. The plant was apparently a Fucus or sea-weed; its stem was rather more than onefourth of an inch in width, and divided dichotomously into numerous branches, covering part of the surface of the stone for about a foot or so in length. The few plants found in this locality had been recently described by the Rev. Mr Duncan, Denholm, in a sketch of the geology of the district contained in a work on the “History and Antiquities of Roxburghshire," by Alexander Jeffrey, Esq., Jedburgh. Dr Smith believed it was the first time any of these fossils had been exhibited to the Society. He had much pleasure in presenting this specimen to the Natural History Museum of the University.
Professor Balfour said he had no doubt the plant was a Fucus; but more than that he could not determine.
Dr Smith exhibited another fossil remain from the same Upper Old Red, in this instance, of Berwickshire ; it was found in a Red Sandstone quarry, opened some years ago on the side of the Black Hill, near Earlston, and was of considerable interest, being the only specimen of a fossil, as far as he could learn, that had ever been discovered there. The specimen is a beautifully sharp and perfect impression of a somewhat triangularly shaped group of palatal teeth ; it measures of an inch in length
by about f in its greatest breadth, and exhibits a transverse, or rather radiating, series of eight depressions, gradually increasing in depth, and showing lines of punctures, corresponding, he supposed, to the rows of the projecting teeth ; and the fossil was all the more strikingly displayed from the colour of the sandstone being completely discharged around the cast, which appears as a patch of white, in the dull red of the surrounding stone. He sent the fossil for examination to Mr Hugh Miller a few months before his lamented death, and received, in reply, the following interesting note :
“SARUBMOUNT, 30th June 1856. "MY DEAR SIR,_Your fossil is the Old Red Ctenodus of Agassiz (his Coal Measure Ctenodus belongs to a different genus); but though he gives it (his Old Red Ctenodus) a generic standing of its own, it is in reality a portion of the previously described Dipterian genus. The Dipterus had two triangularly arranged groups of teeth on its palate, and your specimen is a remarkably distinct impression made by one of these I could show you groups of teeth, were you to do me the pleasure of looking in upon me here, that would fit into your impression well nigh as exactly as a seal would into the wax which it had stamped. Your specimen is the second of Dipterus which I have now seen from the Upper Old · Red Sandstone. The first,—a gill cover,-is in the collection of Mr Patrick Duff of Elgin. I have been prostrated by another attack of my old enemy, inflammation of the lungs, and, after being confined to my bed for a fortnight, am but slowly recovering. Portobello has many visitors at present; but I have seen little of scientific men, and have had little of scientific conversation for the last three quarters of a twelvemonth ; and should you chance to come this way, it would gratify me much to have half an hour's talk with you among my fossils. Some of my Old Red ones would, I am sure, cast not a little light on the detached organisms of your south-country beds.-I am, my dear Sir, yours very truly,
“Hugh Miller. "Dr John A. Smith.”
Wednesday, 22d December 1858.— William RHIND, Esq., President,
in the Chair.
J. W. Laidlay, Esq. of Seacliff, and John M. Mitchell, Esq., Mayville, Trinity, were elected members of the Society.
The Office-Bearers for the session were elected as follows: