by the parasite, the Cyclops did not seem to suffer much, but moved briskly about in the aquarium; but in specimens where the worm was pretty freely grown the orange-red fat drops which usually filled the animal had disappeared, and the ovaries had become atrophical (the males were not observed to have parasites; they would on account of their small size be destroyed before the worm attained the requisite size.)

As regards the introduction of the parasites, it must be presumed that the eggs of the Tania are swallowed by the Copepoda, which feed on all kinds of organic matter floating in the water, in whose stomach they hatch, and thence migrate through the walls of the stomach into the cavity of the body. The eggs must be uncommonly small to be taken through the narrow passage between the toothed mandibles into the gullet and stomach.

The worms doubtless become developed into Tania in the intestines of one of the numerous fishes which feed on the small Crustacea of the sea, and it appears most probable that this parasite, which has chosen such a circumscribed, and for its kind so unusual a domicile, is the young of the Tania torulosa, which, according to Rudolphi,* infest the Cyprinoidea of our fresh-water lakes, although I have not succeeded hitherto in finding them.†

*

On the supposed Radiolarians and Diatomacea of the Coal-measures. -Professor W. C. Williamson, F.R.S., called attention, at the Dublin Meeting of the British Association, to the Traquaria of Mr. Carruthers, found in the lower coal-measures of Lancashire and Yorkshire, with small spherical objects that observer believes to be Radiolarians like those still living in existing seas. Professor Williamson showed that the radiating projections with which these spheres are surrounded were not siliceous spines like those of the Radiolariæ, but extensions of a continuous membrane which enclosed the entire organism, and which therefore could not have the spicular nature attributed to them. He then demonstrated that within this external membrane is a second inner one, which latter is filled with numerous small vegetable cells, like others shown to exist in the interior of fossil spores and reproductive cryptogamous capsules found in the same beds as those which furnish the Traquaria.

These conditions are so different from those existing in any known recent species of Radiolarian as to lead Professor Williamson to reject the idea of their Radiolarian character; whilst their close organic resemblance to some obviously vegetable conceptacles found in the same coal-measures suggested that the Traquariæ are also vegetable

structures.

The mountain limestone deposits of some British localities contain a vast multitude of minute calcareous organisms which Mr. Sollas and other observers have regarded as Radiolarians. These structures, however, seem to exhibit no satisfactory evidence of being so. In the first place these organisms are now calcareous instead of siliceous. *Hist. Nat. Entozoorum,' ii. p. 111, and Dujardin, 'Helminthes,' p. 584. † 'Zoologischer Anzeiger,' vol. i. p. 74.

It has been suggested that their siliceous elements were removed and replaced by carbonate of lime, but this appears to be most improbable.

Professor Roscoe and Professor Schorlemmer agree in stating that they would require overwhelming evidence before they would be prepared to accept such an explanation of the present condition of these objects or of the fact of the substitution of carbonate of lime for silica, that such an explanation renders necessary.

Count Castracane has published an account of a process by which he reduced numerous specimens of coals to very minute quantities of coal ash, and has stated that he found in these ashes numerous marine and fresh-water Diatomaceæ. Professor Roscoe kindly allowed one of his ablest assistants in his laboratory at Owens College to prepare analyses of a number of coals according to Count Castracane's method. The residual ashes of these preparations have been mounted microscopically by Professor Williamson, and in no one of them can a trace of a diatom be found. Beyond stating the fact, he is wholly unable to account for the discrepancy between his results and those of the Italian observer; so far as his present observations go, he finds himself compelled to conclude that we have no proof of the existence of Radiolarians or of Diatomacea in the British carboniferous rocks.

A short discussion ensued, in which Sir Joseph Hooker, Professor M'Nab, and Dr. Bayley Balfour took part, the views expressed coinciding generally with those of Professor Williamson.

Preservation of Planaria.-Dr. Arnold Lang, of Bern, whilst staying at the zoological station at Naples this year was constantly occupied in the endeavour to find a method of preserving the Planaria which was not only fitted to preserve the exterior form and colour of such tender beings, but would also preserve their histological structure for subsequent sections. He found that pyroligneous acid preserved the form and colour, but destroyed the histological structure; but in an old paper by Blanchard in the Annales des Sciences Naturelles' he met with the statement that the writer used "liqueur salin hydrargyrique." He therefore tried chloride of mercury, and succeeded beyond his expectation by using the following mixture:

6

The process is as follows:-A perfect specimen is carefully placed in a shallow cup of sea-water, and laid on its back. This being done, the sea-water is removed by means of a pipette, so that the worm lies stretched out flat; a sufficient quantity of the mixture is then poured on its abdominal side, when it at first draws itself together a little, but immediately afterwards extends itself, and dies almost directly, stiffened in its natural shape. Any wrinkles that may be formed can easily be straightened with a brush. Half an hour afterwards the mixture is to be removed by a pipette, and 70 per cent. alcohol

added, in two hours 90 per cent. alcohol, and, later on, absolute alcohol. In two days all the specimens will be found to be quite hardened. When stained (he recommends picrocarmine in pretty weak solution, and soaking for several days), all the Planaria thus treated preserve their histological structure perfectly well. There is inconvenience in imbedding in paraffin, as in consequence of the great wrinkling the parenchyma of the body is torn asunder. However, by gradually applying turpentine in a strong solution of paraffin this wrinkling can be avoided.

By this method the most delicate Planaria, as e. g. Leptoplana, Proceros aurantiacus, cristatus, Thysanozoon, &c., can be prepared so as to partly retain the colours they possessed when living.*

"Commercial Microscopy."-At the "Écoles Supérieures de Commerce et d'Industrie" of Rouen has been established a course of instruction on the application of the microscope to commercial purposes. Dr. Pennetier, the Director of the Museum of Natural History at Rouen, who has taken charge of the course from its commencement, has addressed a note to the Journal de Micrographie,' detailing the objects he has had in view and the specially satisfactory results hitherto obtained, and urging upon the other commercial schools of the country that they should follow the initiative of Rouen and establish a similar course. Many of the pupils of the Rouen school have owed their admission to the large industrial establishments to the expertness in microscopical manipulation which they acquired under Dr. Pennetier's instruction. It is intended to publish the Doctor's lectures, which include not only the adulterations of food, but the recognition of the nature and proportion of the different kinds of fibres in particular materials, the origin and quality of the hairs employed in hat making and the fur trade, the raw material of which any given paper is composed, the discrimination of true ivory from the substances used for it, and a variety of similar matters. This subject also formed the basis of the recent address of the President of the Quekett Microscopical Club.

Physiology of the Contractile Vacuoles of the Infusoria.—The following observations made by Professor Th. W. Engelmann are adduced by him as demonstrating what hitherto has only been a matter of conjecture, that the contractile reservoirs of the Infusoria empty their contents externally on contracting. A new Infusorium which he was examining (which may be called Chilodon propellens), was the size of a medium specimen of Chilodon cucullulus, and accords with this species also in the limitation of the stripes and cilia on the ventral surface, as also in the presence of a discharging cytostom, in the anterior third of the body, and a simple nucleus in conformity with it. The shape is, however, slender, and towards the posterior end, in which the large contractile bladder is placed, the body is more roundly turned. Thus an approach is made of the hypotrichous to the holotrichous type, which is interesting from a systematic point of view.

The animal swam about with a generally constant but very *Zoologischer Anzeiger,' vol. i. p. 14.

slight motion, for the most part in slight curves. Whenever the contractile reservoir became contracted, which occurred pretty regularly at intervals of about half a minute, and took place very suddenly, there succeeded a jerking kind of acceleration of the forward movement. If the animal happened to be previously stationary, it made a jerking forward movement at the instant of the systole of about a quarter its length. A simultaneous acceleration of the very sluggish ciliar motion could not be discerned at all. The phenomenon can only be explained, therefore, by the rebound caused by the fluid ejected from the contractile bladder at the systole.

With this harmonizes the fact that the hindermost section of the body shrunk together at the systole into a thin, empty, longitudinally folded sac, without there being any appearance of even the slightest increase of volume of the front part of the body. It is certain, therefore, in the case before us, that a very large portion, perhaps the whole quantity, of the fluid contents of the contractile bladder was emptied outwards during the systole.

As the re-expansion of the bladder, as is generally the case, took place very slowly, it could not be decided whether any fluid could be directly sucked in from without. He considers this, however, to be highly improbable, amongst other reasons, because he never succeeded even with other species in seeing the contractile vacuoles fill themselves with coloured fluid from that which surrounded them.*

White of Egg as an Imbedding Substance.-The best substance for imbedding small objects with a view to the preparation of sections is one that can be hardened to any required degree, is easily cut, is transparent, and allows of the section being placed in balsam or dammar immediately after it is prepared.

These requisites are found in the ordinary white of egg of the fowl.

The object to be imbedded (which is best stained beforehand) must have lain for one or more hours, according to its size and penetrability, in white of egg, so as to become thoroughly penetrated by it. There must be no alcohol left in the object, as it gives rise to blisters in the course of the subsequent process, and thereby produces holes in the imbedding substance.

The object thus soaked is now placed in an oblong box of stiff close-made paper folded or pasted together filled with the albumen. The position of the object may be fixed if necessary by a needle passing through the upper part of the box, which can be easily withdrawn after the hardening.

The box thus filled must be exposed to hot steam or, still better, to hot air. After about twenty minutes the albumen becomes hard enough, and the box should then be put into strong spirit, which in the course of a few days must be changed once or twice, to be finally replaced by absolute alcohol. Several days after this treatment the objects are ready for cutting. The paper walls of the box may be removed with a knife, and a section of the hardened albumen several

* Zoologischer Anzeiger,' vol. i. p. 121.

millimetres thick taken off, which can be afterwards used for pinning small objects on before placing them in the box.

The dried (dehydrated) pieces can now be cut by the microtome into sections mm. thick, and the section placed at once on the glass slide, where it may be treated as usual with oil of cloves and balsam. If the mass is too hard, it can be softened to any degree by laying it in water. It is far better, however, to let it lie before cutting for a day in oil of cloves (or turpentine), where it becomes transparent as amber, but at the same time a little softer, though still hard enough to be fixed in the microtome.

The imbedding substance appears under the microscope either perfectly homogeneous or in the worst case very finely granulated.

The advantages of this method are that complete series of sections can be permanently produced without much loss of time, and without the different parts of the object being removed from their position, whilst the transparency allows of uninterrupted observation of the position of the object. Moreover, the object need not be so carefully hardened as is required in paraffin. The method is strongly recommended for calcareous and siliceous sponges as well as for worms and the embryos of fowls.*

New American Journal of Microscopy.-Professor Romyn Hitchcock, of New York, announces that it is intended to issue, under his editorship, a quarterly journal, with the title of the American Quarterly Microscopical Journal.' It is to contain, "besides original articles from prominent writers, reprints and translations of the most important papers found in current English, French, and German publications, the Transactions of the New York Microscopical Society, and a complete synopsis of all microscopical matters; and to this end abstracts will be given of every article published during each quarter to which the editor has access, or where abstracts are inadmissible, titles of the papers will be given." The journal is to be "absolutely independent of any business enterprise, and published entirely in the interests of microscopical science."

Anaerobiosis of Micro-Organisms.-The following note by M. Gunning was read at the French Academy on 1st July:-At the meeting of the Academy of Sciences of Amsterdam of the 29th April, 1877, I pointed out that ferrous ferrocyanide was a reagent very sensible to oxygen, and demonstrated by this means that the apparatus and media ordinarily in use for the culture of micro-organisms could not be exempt from oxygen by the methods recommended for that end.

These observations threw a legitimate doubt on the experiments on which the doctrine of anaerobiosis is based, and I have naturally been led to repeat these experiments under conditions which allow this new point of view to be taken account of. Admitting the practical impossibility of obtaining spaces where the absolute absence of oxygen could be proved, I have used glass flasks hermetically sealed, in

* Prof. Selenka, in ‘Zoologischer Anzeiger,' vol. i. p. 130.