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448 Organization of Fossil Plants of the Coal Measures. [Mar. 27, previous memoir (“ Phil. Trans.” 1874, p. 56), I ventured to doubt the correctness of Mr. Carruthers' conclusions, and expressed my conviction that these objects resembled spores rather than protozoan skeletons. Further study of their details of structure has only strengthened this opinion which has also received the important support of Professors Hæckel and Strasburger, of Jena, both of whom have carefully studied my collection of specimens. These objects are small spheres—the sphere-wall of which is prolonged into a series of long radiating tubes not unlike the muricated spines of a Cidaris. In their young state each murication gives off a delicate thread or threads, which ramified freely in an apparently mucilaginous or gelatinous, structureless, investing magma. In older specimens these threads developed into branching and radiating cylindrical tubes which, like the primary ones, had very thin walls. Within the outer sphere-wall, which consists of the coalesced bases of these branching tubes, were at least two other thin layers of membrane, and in several of the specimens the interior of the capsule is filled with cells, exactly like those seen in the corresponding cavities of Lycopodiaceous macrospores found in the Halifax deposits from which the finest Traquairice have been obtained. These objects differ considerably from all known reproductive structures; but I agree

with Professor Hæckel in his very decided rejection of them from the Radiolarian group of organisms, and with his conclusion that they are vegetable and not animal structures. Professor Strasburger thinks it most probable that their affinities are with the macrospores of the Rhizocarpæ.

In my previous memoir I gave three very small figures of some minute objects, which exactly resemble, in their minutest details, the zygospores of some of the Desmidiaceæ. Many additional examples of these objects have been discovered, enabling me to throw further light upon them. Their resemblance to these zygospores has been made increasingly obvious, but I dare not venture to assign to them a Desmidiaceous origin, since the most extended research, and the resulting discovery of large numbers of these organisms, have yet failed to bring to light the faintest trace of a true Desmid. Under these circumstances I have assigned to several species of these organisms the generic name of Zygosporites.

The seed described in my last memoir but one, under the name of Lagenostoma ovoides, always exhibited a thick carbonised testa, in which no structure could be observed. I have now discovered that the thick outer layer consisted of very hard cubical or slightly oblong schlerenchymatous cells, whilst a thin and delicate inner membrane was composed of small spiral prosenchymatous ones.

An additional specimen of the woody axis of Dadoxylon exhibits the paired divergent structures passing outwards to the back in the shape of two large, radial prolongations of the cellular pith; and which must obviously have gone off the branches-either to ordinary ones or to pairs of fruit-spikes.

Myriads of the vegetable fragments both from Oldham and Halifax are drilled in all directions with rounded insect or worm borings, and further traces of these xylophagous animals are seen in innumerable clusters of small Coprolites of various sizes; the size of those com. posing each cluster being uniform.

Desirous of verifying Count Castracane's alleged discovery of Diatoms in coal, specimens of twenty-two examples of coal from various localities in Yorkshire, Lancashire, and Australia were reduced, after the Count's method, to a small residue of ash. This work was done for me in the chemical laboratory of Owens College through the kindness of Professor Roscoe. Like Mr. F. Kitton, of Norwich, the Rev. E. O'Meara, of Dublin, and the Rev. G. Davidson, of Logie Coldstone, I have failed to discover the slightest trace of these organisms in coal.

The last objects described are some minute organisms from the Carboniferous limestones of Rhydmwyn, in Flintshire, and which were supposed by Professor Judd to have been siliceous Radiolarians from which the silica had disappeared and been replaced by carbonate of lime. I fail to find any confirmation of this conclusion. The objects appear to me to constitute an altogether new group of calcareous spherical organisms that may either have been allied to the Foramnifera, or have had some affinities with the Rhabdoliths and Coccoliths. I have proposed for several species of the organisms the generic name of Calcisphæra. Myriads of objects of similar character, but of larger size, constitute the greater portion of a Corniferous limestone from the Devonian beds of Kelly's Island, U.S.A.

II. “Observations on the Physiology and Histology of Convoluta

Schultzii." By P. GEDDES. Communicated by J. BURDON
SANDERSON, M.D., F.R.S., Professor of Physiology in
University College, London. Received March 10, 1879.

Parr I.-Physiology. Chlorophylloid green colouring matters are known to exist in the tissues of a not inconsiderable number of animals belonging to very various invertebrate groups-Protozoa, Porifera, Cælenterata, Vermes, and even Crustacea ; * but all information as to the function of chlorophyll in the animal organism is wanting. Wöhler, it is true, found many years ago that Chlamydomonas, Euglena, &c., evolve oxygen in sunlight, and Schmidt prepared from Euglena viridis a body isomeric with starch, though of widely different properties, his paramylon; * but these facts seemed as much to point towards the algoid nature of these long disputed organisms as to warrant our supposing a more or less vegetable mode of life in animals so well organised, and so evidently carnivorous as Coelenterates and Turbellarians, especially as the only recorded experiment, that of Max Schultzef on Vortex viridis, yielded a totally negative result. Some such hypothesis, however, can hardly help recurring to the observer of the light-seeking habit of Hydra viridis,

* See list in Sach's "Botany,” Eng. ed., p. 687, note.

Last spring, when at the Laboratoire de Zoologie Expérimentale of M. de Lacaze-Duthiers, at Roscoff, I was much interested by the green Rhabdoccele Planarian, Convoluta Schultzii, 0. Schm., crowds of which, lying at the bottom of the shallow pools left by the retreating tide, resembled at first sight patches of green filamentous algæ. Their abundance in fine weather on the surface of the white sand, covered only by an inch or two of water apparently to bask in the sun, was very striking, at once suggesting that their chlorophyll thus so favourably situated must have its ordinary vegetable functions. I accordingly returned to Roscoff in the autumn to make experiments.

The mode of procedure was evidently to expose the Planarians to sunlight to observe whether any gas was evolved, and if so to analyse it qualitatively and quantitatively. After one or two trials a form of apparatus—the simplest possible—was found, which answered admirably. It merely consisted of a couple of the round shallow glass dishes used in the laboratory as small aquaria, the edge of one fitting as nearly as possible, when inverted, into the bottom of the other. Into the larger vessel were put Planarians enough to cover the bottom; it was then gently sunk in the pneumatic trough (a tub of sea water), and the smaller, also full, inverted into it. The apparatus was then placed on a shelf in the sunshine, and left to itself. The movements of the animals were greatly accelerated by the exposure, and in a quarter of an hour minute bubbles of gas were to be seen in the film of mucus plentifully secreted by the Planarians. These bubbles rapidly increased in number and volume until they buoyed up the whole sheet of mucus with its entangled Planarians and grains of sand to the top of the water in the inverted dish. Here the evolution of

gas

continued more actively than ever, until the animals had disengaged themselves and descended to the bottom, there to recommence as before, the mucus meanwhile dissolving and allowing the bubbles freely to unite. Thus the first half of the inquiry was answered in the affirmative.

#

Gorup Besanez, "Traité d'Analyse Zoochimique,” p. 127. Euglena is claimed by both Sachs and Claus in their manuals of Botany and Zoology respectively.

I “ Beiträge zur Naturgeschichte der Turbellarien." § “Neue Rhabdocælen.” Wiener Sitzungsb., 1852.

The determination of the nature of the evolved gas was readily effected. On transferring the quantity produced in one or two vessels to a small test-tube, and plunging into it a match with red hot tip, there was to be seen the white glow characteristic of dilute oxygen. A large glass tube of tolerably even calibre, about 75 centims. long, was sealed at one end, and bent at about two-thirds of its length from that point at an angle of 60°. It was then filled with water, and the water in the long sealed arm almost entirely replaced by gas at the pneumatic trough. This comparatively large quantity of gas, about 60 centims. cube, was obtained by exposing a dozen or so of apparatuses exactly similar to that described, except that bell-jars, sealed funnels, &c., sometimes replaced the upper flat dish, and white soup plates the lower. They were set agoing about noon, and the abundant gas yielded by thus exposing a surface of nearly a third of a square metre covered with Planarians was collected at sunset.

On agitating the gas with a solution of potassic hydrate a barely appreciable absorption of carbonic anhydride took place, but on the addition of pyrogallic acid with renewed agitation, the intense brown coloration, with rapid and considerable ascent of the fluid in the long arm of the tube, confirmed the presence of a large percentage of oxygen.

The results of many experiments varied from 43 to 52 per cent. of oxygen; the higher number representing the amount of gas given off by freshly collected Planarians, and the lower that yielded on the second or third day of their subjection to experiment. In order to judge of the degree of accuracy which I could obtain by this rough method of analysis, I estimated by it the oxygen of common air, and obtained 19.9 per cent. instead of 20:9. Allowing for this loss of about 5 per cent., it may safely be asserted that the gas evolved by these animals does not contain less than from 45 to 55 per 100 of oxygen.

The Planarians are little the worse after a 24 hours' journey from Roscoff to Paris, and when placed in an aquarium they instantly betake themselves to the side next the window, and live there resting on the bottom or clinging to the side for four or five weeks without food. They certainly diminish considerably in size, yet I have little doubt that they go on decomposing CO2 and assimilating the carbon even in the dull winter daylight, for when kept in darkness they generally died much sooner.

The conspicuousness of the Planarians on the sandy beach, far from the shelter which rocks or algæ might afford, has been already mentioned, and at first sight one is apt to think that they must be the easy prey of all the larger shore-frequenting animals, and to wonder that so many escape. But the observation made by Wallace and Belt for so many higher animals—that conspicuously coloured forms are nauseous and uneatable-holds good here. So strong and disagreeable is the odour, to which the taste doubtless corresponds, that this alone might be relied upon as a protection against the least fastidious of fishes or Crustaceans.

The chemical examination of the animal yields results of interest. Treated with alcohol, a yellow substance, contained in small elongated vesicles, aggregations of which are dotted over the integument, dissolves out very rapidly, yielding a golden solution without definite spectrum. This has of course nothing to do with xanthophyll. Continued treatment with alcohol dissolves out the chlorophyll, of which the magnificent green solution is tolerably permanent. As former observers have shown, it has a red fluorescence, and gives a spectrum closely resembling that of vegetable chlorophyll.

Knowing that these animals decompose carbonic acid, and evolve oxygen, one naturally enquires whether they do not still more com. pletely resemble green plants in fixing the carbon in the same way. To answer this question, the residue of the Planarians, coagulated and decolorised by repeated treatment with alcohol and ether, was boiled with water, and filtered off. The clear solution gave with iodine solution a deep blue coloration, which disappeared on heating, and reappeared on cooling, indicating the presence in quantity of ordinary vegetable starch.

To separate and purify this starch on a large scale, some hundred grammes of Planarians were repeatedly boiled in water. The solution (which had an intensely alkaline reaction) was treated with four or five times its bulk of strong alcohol, and allowed to stand for some days. The flocculent precipitate was collected, decolorised with ether, and washed with cold water. A great part of it dissolved, leaving the starch behind, and the filtered solution gave with iodine the red-brown coloration characteristic of dextrine. To ascertain whether this dextrine was naturally present, or had merely been produced at the expense of the starch by boiling in alkaline solution, fresh animals were treated with cold water, but the solution contained no dextrine. Treatment of a fresh microscopic preparation with iodine showed the presence of glycogen, in the colourless amoeboid cells of the mesoderm, but there is no chemical means of separating glycogen from starch. Probably the best way of obtaining pure starch from these animals would be by imitating the mechanical process of the potato mill.

The intense alkalinity of the animals is very striking. Even in the fresh state, but still more when dried in the warm chamber, they give off vapours with an odour resembling that of trimethylamine, and in sach abundance as to cause neighbourir solutions to yield the reactions of an alkaloid. A quantity of animals was distilled, and the alkaline fumes received in dilute hydrochloric acid. The resultant salt

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