most external and internal fibres are more or less longitudinal, and the deeper or more central fibres become more and more oblique as the centre of the parietes is reached. The longitudinal intersect the very oblique at nearly right angles; the slightly oblique and oblique at more acute angles. Dr. Pettigrew considers that there are indications of seven layers of fibres, three external, three internal, and one intermediate; but he uses the term layer in a more restricted sense than in his former papers on the heart and bladder, and now admits that there is a mutual interchange of fibres between the different layers.

Minute Structure of the Liver.-New views with regard to this matter have lately come before the world, and seem to be very generally accepted by the leading histologists. Hering, Eberth, and other foreign observers, have renounced Dr. Beale's view, as also that which attributes to the bile-ducts the formation of distinct capillaries within the lobules, having a membrana propria like the blood capillaries, and in contact only externally with the liver-cells. Professor Turner supports the new view, which is, that the bile passes to the periphery of the lobule in channels, which lie between and have their walls formed by the liver-cells, and which communicate with the interlobular branches of the hepatic duct. Preparations of rabbit's liver, in which the bile-ducts have been injected immediately after the death of the animal, are the data which have lead to this new conception. Professor Hering has also studied the lives of many other mammals and reptiles.

The Gall-Bladder.-The gall-bag is a most strangely variable organ. Dr. Macalister states that it is constantly present in bimana, quadrumana, cheiroptera, insectivora, carnivora, marsupialia, monotremata; absent from cetacea; variable in edentata, pachydermata, rodentia, and ruminantia. As a rule it is present in birds and reptiles, and almost universally in fish. An explanation of its variability (varying sometimes even in the same species) is that it is required in those animals whose intervals of feeding are protracted, and is of little use in those in which the bile flows continuously from the liver, to aid in the almost constant process of digestion.

The Axolotl and its Gill-tufts.-It has been long thought that the Mexican perennibranchiate Salamander might prove to be merely a larval form, and develop into a true Salamandroid. Moreover, the presence or absence of gills or their apertures in the adult state has been found to be merely a question of degree, and not of much taxonomical value. Van der Hoeven pointed out that the giant proteid of Japan could not be separated from the American Menopoma, though in the first the gill apertures are lost in adult life, and in the second they are persistent. From the experiments of M. Auguste Duméril on the Axolotls now alive and breeding in the ménagerie at Paris, it appears that in this creature the per

sistence of the gills is purely accidental: they are of no functional importance, and may be cut off without injuring the animal. When cut, they grow again, and may be again cut. Persistence in cutting the gills causes the Axolotl at length to undergo certain changes in colour and appearance, and to approach more closely to the fullydeveloped Salamandroid. It is a remarkable thing that even whilst these gills, evidently the mere relics of larval structure, are attached to the Axolotl, it becomes sexually mature, and breeds (as it has done at Paris). M. Duméril appears to show that sometimes an Axolotl may lose its gills at an early period of life-in other cases, perhaps not at all—and there is great variability in the time when the supply of blood to these parts is cut off, and an absorptive process commenced. Perhaps the diminution of accessible nutriment might have some effect in causing an earlier absorption of the appendages. The most important of M. Duméril's observations-zoologicallyis the discovery that the Axolotl does spontaneously lose its gilltufts and tail crest, and becomes a true Salamandroid-approaching certain North American forms. In fact, M. Duméril says the Axolotls are only the tadpoles of the Amblystomi, and, most strange to say, have the power of sexual reproduction as tadpoles. Does not this open up a case for the students of natural selection? The tadpole of a northerly Batrachian, when placed in a tropical clime, tends to retain its tadpole form, and to acquire sexual maturity in that condition (or vice versa). But there are almost the same remarkable facts with regard to our own common newt.

Amphioxus and Nerve Termination.-M. P. Bert has some remarks on this lowest of vertebrates in the 'Comptes Rendus.' It has been taken this year for the first time on the oceanic shores of France, though many specimens have been observed on the English south coast. M. Bert corrects some of the errors made by M. de Quatrefages. He denies the existence of the lateral canal opening at the side of the mouth, and describes the position of the abdominal pore and its relation to the body cavity. Like all other fish, Amphioxus has the generative glands early developed, and it has been strangely asserted by Agassiz that it is an immature form. M. Bert has seen it spontaneously discharge the spermatic fluid, which proves the assertion to be baseless. He also speaks of the termination of the nerves in corpuscular bodies. This gives us an opportunity to refer to a paper on the same termination of nerves in various animals published in M. Robin's Journal. In these, also, corpuscular terminations are described closely connected with muscle fibres. M. Bert very properly maintains that in Amphioxus there is a retiform or endless disposition of the finer nerve twigs as well as these corpuscles. No doubt the reconciliation between the views of Dr. Beale and of his opponents (who are now becoming very few in number) will be found in admitting fully both methods of ter

mination. It seems not at all improbable that the corpuscular bodies in connection with nerve-ending and muscle fibre may be connected with sensation-that form of it, which is called the muscular sense, just as other corpuscular bodies (tactile, &c.) are connected with the more obvious perception of heat, cold, and other vibrations. "Plaques motrices" will have to be abandoned as such, and regarded merely as corpuscles of muscular sense.

Development of Cuttle Fish.-The distinguished Russian ob server Mecznikow has been studying the development of Sepiola-a little Cephalopod common at Naples. He is led to deny some statements of Kölliker, and shows that the development proceeds from two layers. The skin and sense organs are developed as in Vertebrata, and what is most remarkable, a relationship between the Vertebrate's notochord and the so-called "cuttle-bone" is maintained. M. Mecznikow rejects all analogy between the foot of ordinary mollusks and the siphon, as advocated by Huxley. He is equally adverse to the hypothesis of Häckel (a natural philosopher of the Darwinian school) that the Pteropoda are the immediate ancestors of the Cephalopoda.

Insect Architecture.-A curious example of the weaving powers of insects is recorded by Mr. Tomes, of Christ Church, Oxford, in a recent number of the Microscopical Journal.' Mr. Tomes found in ponds on Hampstead Heath small cases made of green conferva and an animal basis; the fibres of conferva were very regularly and neatly interwoven, forming a tube open at each end. In this an insect-larva was found, which is minutely described and figured with its case in a coloured plate. Mr. Tomes considers that the larva belongs to the Trichopterous genus Hydroptila. He describes the habits of the animal and its method of building the case it inhabits. The perfect insect is not known to Mr. Tomes.

Structure and Differences of Egg-shells.-Dr. Blasius undertook the microscopic examination of birds'-eggs, in order to ascertain whether they presented any characters which would serve to separate the larger groups of birds. An account of his researches, which have been most extensive and detailed, appears in Kölliker's Zeitschrift,' 3rd part. It appears that the microscopic differences are not constant or reliable, and that oology must stand just where it did as regards systematic ornithology, even after such careful observations as those of Dr. Blasius.

THE PUBLIC HEALTH.

Ir any one wishes for a demonstration of the need of change in the Municipal Management of London, he should visit the Metropolis just after a snow storm. Such a storm visited London on the night of the 8th of December, 1867. The next morning, although hundreds of poor men were begging in the streets, being thrown out of work by the snow, there was no effort made to clear the streets and pavements of that snow; and the consequence was that, snow being trampled by the feet of men and horses into ice, numerous accidents to men and horses occurred. That the streets are allowed to remain in this disgraceful state does not arise from want of legal power to put them in a safe condition, but from an entire neglect of duty. Thus the police have the power to fine every person forty shillings who does not cleanse the footway in front of his house before a given time after a fall of snow; but they seldom or ever exercise this power. The greatest sinners in this respect are the government offices and the authorities who preside over our public parks. The footway around these parks is never swept. The vestries try to clean the streets, but their surveyors never have organizing skill enough to get the poor unemployed men together to do this necessary work. If the snow cannot be got away, an immense saving of horse flesh and horse pain would be effected by throwing gravel or sand down the principal thoroughfares. But the vestries will not see what they have to do with protecting strangers' horses passing through their thoroughfares. The loss by the payment for gravel and labour would appear against them in the rate book, and as the saving of life would not appear, they will have nothing to do with it. We should not have referred so much in detail to this London grievance if it were not that it illustrates a principle. London is badly managed because it is split up into forty Vestries, no two of which will act in concert, and none of them will do anything for the public good. Above all things we want in London public-spirited men, men who will sacrifice their own private interests and that of their parishes for the public good. It is too much to expect that the forty or fifty little parliaments by which the Metropolis is governed, with their two or three thousand members should ever produce a majority of public-spirited men. The present system is the worst possible that could be devised for securing the public good. What we really want is that the Metropolis should be governed as a whole, and that it should not be split up into forty or fifty parishes, each having its own narrow-minded

parliament, bent on opposing every advantage to its neighbours, on the ground that it would injure itself. It is to break up this system that Mr. J. S. Mill brought forward a measure for the Reform of the Municipal Government of the Metropolis. It is not necessary that we should here enter into any details of this measure. We must regard it as a means to an end. The concentration of authority which he proposes in this bill, and the administrative power which it gives to bodies having larger powers and wider administrative districts than at present exist in London, would undoubtedly be the means of effecting an immense amount of benefit. This excellent measure has been opposed by nearly every vestry in London. The great excuse for opposition has been that it would increase the expense of the Local Government of the Metropolis. This is regarded as a sufficient ground for opposition to any measure. The cry of expense is raised against any measure, whatever may be its promise of prospective gain. The fact is, that when a thoroughly careful examination is made of Mr. Mill's bill, it will be found that a great economy will be ultimately effected. Instead of the multitude of officers with small salaries, which are now the burdens of London parishes, a few effective officers with larger salaries will be appointed. For instance, instead of a large number of medical officers of health, half of whom are confessedly paid for doing nothing, there would be five or six men appointed, who would attend to their duties, and not be allowed to hold sinecures, as is at present the case. In the interests of public health we advocate this measure. As an instance of how the present vestries treat their medical officers, we may give a report of what occurred in the Vestry of St. James's, Westminster, on the 5th of December last, when the medical officer of health, calling attention to the deaths from typhoid fever among the wealthy inhabitants of that parish, said, "Several cases have come under my notice where life has been lost amongst this class. No one should take a house without a certificate of the drains being properly laid; and bricklayers and builders, neglecting their duties in this respect, should be liable to prosecution and fine." The very idea of a man being prosecuted for killing his neighbours in this way was ridiculed; and the report in the Marylebone Mercury' of the 7th of December, says "The reading of this passage was received with cries of 'Oh, and laughter.' There can be no question that in order that the duties of the medical officer of health should be carried out efficiently, his appointment should be independent of such bodies as the present vestries of London. No effectual sanitary measures can be carried out in many districts of London till the medical officer of health is made independent of the influence which the vestry is now capable of exercising over him.

The question of the position and duties of the Medical Officer of