which different parts of the electric stratification present. He compares these phenomena to those observed when a voltaic current of a certain strength is passed through a chain composed of alternate links of platinum and silver. The author proves, in an ingenious manner, that the dark spaces of the stratifications conduct electricity better than the luminous portions. He also shows, by thermometric observations, that the temperature of the luminous is more elevated than that of the dark portions.

An improvement has been made by M. Bertsch on the somewhat celebrated electric machine of Holtz. The machine is too complicated to allow of description in abstract. With a disc of vulcanite, 50 centimetres diameter, sparks of about 15 centimetres long can be obtained at the rate of from five to ten a second, and having sufficient tension to pierce a glass one centimetre thick, and to illuminate continuously a tube of rarefied gas one metre long. In thirty or forty seconds it will charge a battery having an interior surface of two square metres, which will burn up a thick iron wire one metre in length.

The subject of thermo-electricity has lately attracted much attention. Our knowledge has now been considerably enriched by an elaborate memoir by M. Becquerel on the thermo-electric powers of different alloys, and the construction of thermo-electric batteries. For thermo-piles for low temperature, he recommends an alloy consisting of equal equivalents of antimony and cadmium with one-tenth the weight of bismuth, for the positive metal, and an alloy of ten of bismuth and one of antimony for the negative metal. For piles of a high tension the negative metal should be German silver, and the positive may be either the above antimony, cadmium, and bismuth mixture, or fused and annealed sulphide of copper; the latter stands the greatest heat, but gives also the highest resistance. As sulphide of copper is a very bad conductor of heat, it will scarcely be found necessary to cool the other ends; but this should be done when a metal is used, and the length of the bar should, in that case, be increased. Thermo-electric piles, on account of their low tension, cannot yet replace hydroelectric batteries; but, for special purposes, and particularly for the study of radiant heat, the piles here described offer new facilities, and are, therefore, worthy of attention.

M. Zaliwski-Mikorski has introduced an improvement in the method of filling and emptying the troughs of galvanic batteries of two liquids, such as Groves's or Bunsen's. The permanent part consists of an alternate succession of porous diaphragms and isolated carbons. By means of tubes in the lower part, a liquid poured into one compartment immediately flows into all the analogous

compartments; the whole of them can also be emptied simultaneously with a syphon.

The trough, therefore, need not be moved when it has to be filled or emptied. The zincs, which are loose, rest on the carbons, which project for this purpose at their base; and the effect of removing one, or more, is not to stop, but only to diminish, the intensity of the current. The cement which is most recommended, is one consisting of sulphur, rendered less brittle by a mixture of tar and lampblack.

12. ZOOLOGY AND ANIMAL PHYSIOLOGY.

MORPHOLOGY.

The Skull.-The expression "theory of the skull and vertebrate skeleton," which is now very frequently used, certainly requires a little explanation before the ordinary mind can perceive the meaning it is intended to convey. When a theory of the origin of species is spoken of, we clearly understand what is meant, for we are accustomed to discuss theories of the origin of various other things, besides species; but a "theory of the skull" may relate to its origin, to its use, or to any one of its functions. Mr. Harry Seeley, in a very clever paper on this subject, prefaces his remarks by stating that by a theory of the skull, he means a way of presenting a set of well-known facts, so that they explain themselves. This is really what is meant by Professor Owen when he advances his theory of the skull, and by Professor Huxley when he advances his. Mr. Seeley puts forward a view of the facts known concerning the vertebrate skull, which causes these facts to explain themselves in a way which does not impugn the fundamental truth of the views of either of the two great comparative anatomists, but is in a certain way an attempt to find the truth which lives in both, and is an exceedingly ingenious and interesting essay.

The final conclusion of Mr. Seeley's theory is," That the skull is the terminal segment of the body, and that just as the adjacent segments consist of the pharynx, the larynx, and a vertebra enclosing part of the neural column, so also the skull, which is the termination of these three organs, and where their outlets are visible, must consist of them also; that the brain-case, therefore, (the termination of the neural system), is a modified vertebra, that the bronchial circle of nasal and palatine bones is a modification of the trachea, and that the lower jaw is a modified rib developed by the mouth. The respiratory circle of bones is the key to the skull."

Races of Men.-M. de Quatrefages has brought out a work on anthropology, entitled, Oceanic Races: the Polynesians and their

Migrations.' He follows chiefly the conclusions of the American writer, Mr. Horatio Hall, and adduces evidence that the Polynesians have not been created by nation and on the spot; they are by no means a spontaneous production of the isles on which they are found, nor are they the remnant of a pre-existing population partly destroyed by some cataclysm. Whatever the origin of the islands may be, their inhabitants came there by voluntary migration, or by involuntary dissemination, successively, and advancing from west to east. They set out from the Oriental Archipelago of Asia, have migrated from island to island, and are yet doing so. The earliest migration was probably not antecedent to the Christian era. The race contains mixtures of the black, white, and yellow races, in which the last is least prominent. The author determines, in some cases, the exact period of the migrations and colonizations of various places, extending his researches to the Maories of New Zealand.

The Anthropoid Apes.-A memoir on the anatomy of a new species of chimpanzee has just been published in the Archives du Muséum, by MM. Gratiolet and Edmond Alix. Those who know the scrupulous accuracy and minute descriptive power of the late Professor Gratiolet will appreciate the high value of this work. The specimen was sent over to Paris from the Gaboon, and the authors are inclined to regard it as possibly identical with the tschego mbouvé, or the kooloo kamba of M. Du Chaillu. They, however, complain that the descriptions given by M. Du Chaillu are not sufficient for identification, and hence name the species provisionally, T. Aubrvi; seeing that the skull and skins of both M. Du Chaillu's new species are in the British Museum, it is to be regretted that some attempt at comparison is not made. The figures of the skull given by the authors strongly resemble that of the kooloo kamba in its great prognathism and high development of the temporal region of the skull. Should this species be new, we should have the following species of chimpanzee living at the Gaboon:-T. niger, T. kooloo kamba, T. tschego mbouvé? T. vellerosus, and T. Aubrvi. It really seems desirable that careful comparisons should be instituted between these would-be species. One of the chief points of interest in this work is, that it exhibits the method of description which M. Gratiolet considered as the one to be pursued in describing the complete anatomy of any animal. He had intended to illustrate this in a work on the anatomy of the hippopotamus, when he was unhappily cut off in the midst of his labours.

M. de Langle describes, in a letter to the French Academy, the manners of a young gorilla, which was taken from its mother. It clings tightly round the neck of anyone who carries it, and can hardly be forced to let go, this being its natural position with its mother. It eats bread greedily, preferring it to fruit.

Externally and internally Parasitic Acari.-M. Guérin Méneville notes, in a letter to the French Academy, the sudden appearance of innumerable acari - Tyroglyphus fecule on his potatoes. In less than eight days these little arachnidans became so abundant as entirely to cover the potatoes, and form a seething mass. He is at a loss to account for their remarkable and sudden appearance.

Mr. Charles Robertson, Demonstrator of Anatomy in the University of Oxford, has lately described a form of acarus found inside pigeons, chiefly amongst the connective tissue of the skin, the large veins near the heart, and on the surface of the pericardium. In some respects the acarus described agrees with Sarcoptes, but has an extraordinary maggot-like appearance. The discovery of an external parasite inside an animal, in such numbers as Mr. Robertson records, is very remarkable. Colonel Montagu found such acari in the gannet, and Mr. Robertson has since found them in the pelican. It is exceedingly difficult to account for their appearance. Are they undergoing a normal phase of their existence, or have they been accidentally introduced in the cases recorded, and found the habitat a favourable one?

Nerve endings.-The termination of nerves in muscle is a subject which still continues to call forth the energies of microscopic observers. Dr. Moxon has published a paper in the last number of the Microscopical Journal,' in which he describes the peripheral termination of a motor nerve of an insect. The case described by Dr. Moxon is one of considerable importance, since the insectlarva (culex) is one which is plentifully distributed, and any competent microscopist can easily find the particular muscle and assure himself of the mode of motor nerve ending. The muscle is the retractor antennæ, and on it the nerve described ends in a corpuscular expansion. This is most clearly figured and described in the paper, and is of course a strong case against the views of Dr. Beale, and in favour of those of Continental observers, unless there be one mode of termination of motor nerves in frogs and another in insect larvæ. Dr. Moxon cannot in any way give his support to Dr. Beale's view, but thinks the question discussed between Rouget and Kühne as to the exact method of termination, after the nerve has penetrated the muscle-fibre, is that to which attention should be given.

PHYSIOLOGY.

Action of Prussic Acid in small quantities. It is rarely that our brothers in the Colonies contribute anything to the literature of physiology, which is of real value. Mr. Ralph has, however, lately read a paper before the Medical Society of Victoria of

great interest, "On the Effects of Prussic Acid on the Animal Economy." He administered prussic acid to various animals, flies, bees, maggots, rabbits, &c., and in all cases found concretions of Prussian blue afterwards in the tissues, having failed to detect any such coloured masses previously. In two cases of persons to whom prussic acid was administered as a medicine the films and concretions of Prussian blue were noticed in the blood with the microscope. From these observations which appear to have been most carefully made, he feels satisfied that prussic acid causes a change in some of the constituents of the blood, that it attacks the iron when in some particular condition, and, with perhaps the aid of some alkaline base, the Prussian blue is formed, which may vary very much, as is well known, in its constitution. He further finds that at the same time as the ferrocyanide is formed, amylaceous particles are set free, and draws some valuable conclusions as to the formation of corpora amylacea, and suggests that the iron in the blood may not improbably have other functions besides that connected with oxygen; viz. that of being a vehicle or medium for holding carbon and hydrogen together, and for their more ready distribution to the tissues. Dr. Hassall some years since pointed out the formation of indigo in the urine and tissues of the body. Mr. Ralph's experiments show that the blue particles are not indigo, but Prussian blue or a cyanide of iron.

The physiological working of Deodorizing agents.-At a recent meeting of the Ashmolean Society of Oxford, Mr. Chapman, of Merton College, described some experiments which he had been performing with regard to the action of various deodorizing agents on the life of ferments. Equal portions of water containing decomposing animal matter were taken, one was left untouched, to a second carbolic acid was added; to a third, sulphate of iron; to another, Condy's fluid, and to a fourth, Burnett's. The development of vegetable life, which is the invariable accompaniment of the destructive fermentation of organic matters, was then looked for daily, in each portion of liquid. In the untouched liquid, abundance of bacteria, and afterwards infusoria, were apparent. In that to which carbolic acid was added the organisms previously occupying the solution were killed, but their lifeless bodies were preserved and remained floating in the liquid. In the case of sulphate of iron there was complete destruction of all trace of organized matter, and a brown sediment of peroxide fell to the bottom of the vessel. Burnett's fluid had an action similar to that of carbolic acid, whilst Condy's fluid was found to act at first similarly to sulphate of iron, but after a short period its virtue was exhausted and a re-development of ferment-causing organisms occurred. The subject is one of great interest, and might be treated in a much more philosophical way than that which Mr. Chapman has adopted. His only object