so distinct that they evidently indicate diffe rent species. Mr. Murray believes, however, that only one form is met with on one sphere; and that in order to produce the numerous forms figured by Hæckel and Oscar Schmidt, all of which, and many additional varieties, he has observed, the spheres must vary in age and development, or in kind. Their constant presence in the surfacenet, in surface-water drawn in a bucket, and in the stomachs of surface animals, sufficiently prove that, like the ooze-forming foraminiferes, the coccoliths and rhabdoliths, which enter so largely into the composition of the recent deep-sea calcareous formations, live on the surface and at intermediate depths, and sink to the bottom after death. Coccospheres and rhabdospheres have a very wide but not an unlimited distribution. From the Cape of Good Hope they rapidly decreased in number on the surface, and at the bottom as we progressed southwards. The proportion of their remains in the Globigerina ooze near the Crozets and Prince Edward Island was comparatively small; and to this circumstance the extreme clearness and the unusual appearance of being composed of Globigerinæ alone was probably mainly due. We found the same kind of ooze nearly free from coccoliths and rhabdoliths in what may be considered about a corresponding latitude in the north, to the west of Faröe.

Before leaving the subject of the modern chalk, it may be convenient to pass on to stations 158, 159, and 160, on March 7th, roth, and 13th, on our return voyage from the ice. The first two of these, at depths of 1,800 and 2, 150 fathoms respectively, are marked on the chart "Globigerina ooze;" and it will be observed that these soundings nearly correspond in latitude with the like belt which we crossed going southwards; the third sounding at a depth of 2,600 fathoms is marked "red clay."

According to our present experience the deposit of Globigerina ooze is limited to water of a certain depth, the extreme limit of the pure characteristic formation being placed at a depth of somewhere about 2,250 fathoms. Crossing from these shallower regions occupied by the ooze into deeper soundings, we find universally that the calcareous formation gradually passes into and is finally replaced by an extremely fine pure clay, which occupies, speaking generally, all depths below 2,500 fathoms, and consists almost entirely of a silicate of the red oxide of iron and alumina. The transition is very slow, and extends over several hundred fathoms of increasing depth; the shells gradually lose their sharpness of outline and assume a kind of rotten look and a brownish colour, and become more and more mixed with a fine amorphous red-brown powder, which increases steadily in proportion until the lime has almost entirely disappeared. This brown matter is in the finest possible state of subdivision, so fine that when, after sifting it to separate any organisms it might contain, we put it into jars to settle, it remained for days in suspension, giving the water very much the appearance and colour of chocolate.

or

66

In indicating the nature of the bottom on the charts, we came, from experience and without any theoretical consideration, to use three terms for soundings in deep water. Two of these, Gl. oz. and r. cl., were very definite, and indicated strongly marked formations, with apparently but few characters in common; but we frequently got soundings which we could not exactly call either "Globigerina ooze "red clay;" and before we were fully aware of the nature of these we were in the habit of indicating them as "grey ooze" (gr. oz.) We now recognise the " grey ooze as an intermediate stage between the Globigerina ooze and the red clay; we find that on one side as it were of an ideal line, the red clay contains more and more of the material of the calcareous ooze, while on the other the ooze is mixed with an increasing proportion of "red clay.'

Although we have met with the same phenomenon so frequently that we were at length able to predict the nature of the bottom from the depth of the sounds with absolute certainty for the Atlantic and the Southern Sea, we had perhaps the best opportunity of observing it in our first section across the Atlantic, between Teneriffe and St. Thomas. The first four stations on this section, at depths from 1,525 to 2,220 fathoms, show Globigerina ooze. From the last of these, which is about 300 miles from Teneriffe, the depth gradually increases to 2,740 fathoms at 500, and 2,950 fathoms at 750 miles from Teneriffe. The bottom in these two soundings might have been called " ooze;" for although its nature has altered entirely from the Globigerina ooze, the red clay into which it is rapidly passing still contains a considerable admixture of carbonate of lime.

grey

The depth goes on increasing to a distance of 1,150 miles from Teneriffe, when it reaches 3,150 fathoms; there the clay is pure and smooth, and contains scarcely a trace of lime. From this great depth the bottom gradually rises, and with decreasing depth the grey colour and the calcareous composition of the ooze return. Three soundings in 2,050, 1,900, and 1,950 fathoms on the "Dolphin Rise," gave highly characteristic examples of the Globigerina formation. Passing from the middle plateau of the Atlantic into the western trough with depths a little over 3,000 fathoms, the red clay returned in all its purity and our last sounding in 1,420 fathoms before reaching Sombrero, restored the Globigerina ooze with its peculiar

associated fauna.

THE Journal of the Chemical Society for October commences with a paper, by Prof. Roscoe, On a new chloride of uranium. The new compound is the pentachloride UCl5, obtained by passing chlorine over a heated mixture of any oxide of uranium and charcoal. If the current of chlorine is slow, the substance forms dark needle-shaped crystals with a green metallic lustre and ruby red by transmitted light. When the chlorine is passed rapidly, UCI, is formed as a brown powder. The compound decomposes on heating into the tetrachloride and free chlorine.The next paper is on suberone, by C. Schorlemmer and R. S. Dale. This body is formed by distilling suberic acid with lime according to the equation—

2C8H14042CO2+ 2H2O + C14H2402.

=

Hexane is produced at the same time, and can be separated by fractional distillation. Pure suberone is a mobile liquid, boiling at 179° to 181°. The molecular formula is C,H1O, and it is oxidised by nitric acid into an acid of the formula C,H1204. The authors have examined the barium, calcium, and silver salts of this acid. The new acid has the same composition as the pimelic acid obtained by Hlasiwetz and Grabowsky from camphoric acid, but its properties are quite different, and it has been provisionally named a-pimelic acid. The authors assign the following constitutional formulæ to suberone and a-pimelic CH2-CH2-CO.OH CH, CH, CH, CO.OH

acid :

CH-CH-CH2

CH2-CH2-CH2

Suberone.

CO

a-Pimelic acid.

Note on the crystalline forms of meconic and a-pimelic acids, by Dr. C. A. Burghardt.-On the action of earth on organic nitrogen, by E. C. C. Stanford. The experiments were made on mixtures of lean meat with ordinary loam-earth, and the author deduces therefrom the following conclusions:-I. Earth mixed with organic nitrogenous matter is an indifferent dryer, and, except in considerable quantity, a poor deodoriser. 2. That the mixtures continuously lose nitrogen to about the extent of 73 per cent. in five months. 3. That the loss is perhaps wholly due to decay, the nitrogen being probably evolved as ammonia. 4. That in such mixtures the earth does not act as an oxidiser, no nitrification taking place. The remainder of the journal is devoted to abstracts from foreign periodicals, many of which have been already noticed in these columns.

Gazzetta Chimica Italiana, fascicolo vi., vii., and viii., October. This part begins with a long and valuable paper by W. Koerner, entitled "Studies of the Isomerism of the bodies known as Aromatic Substances with six Carbon Atoms." This research has led the author to study the action of nitric acid on acetanilide giving rise to the formation of nitro-acetanilide, which is converted by potassium hydrate into a mixture of ortho- and

a

meta-nitroaniline. Para-nitroaniline from ordinary dinitro-benzene is next treated of, then the reduction of meta-nitroaniline. Iodobenzene acted upon by nitric acid yields ortho- and meta-iodo-nitrobenzene, the first of which was converted by the action of nitro sulphuric acid into dinitro derivative, which, on treatment with a dilute solution of potassium hydrate, is converted into the potassium salt of ordinary dinitrophenic acid, and by the action of alcoholic ammonia into ordinary dinitro-aniline. From these reactions the author concludes that this dinitro-iodobenzene has the structural formula I: 2:4. Dinitro-iodobenzene from meta-nitroiodobenzene has been prepared and proved to be identical with the foregoing body; at the same time a small quantity of a second dinitro compound is produced, which the author considers as the iodide of the B dinitrophenol of Huebner and Werner. The dinitro-aniline from this body has been prepared, and the constitution 26 is assigned to it. The author next enters into the consideration of this ẞ dinitrophenol-a table comparing the fusion points of this body and its derivatives with those of the a compounds is given. The brominated derivatives of the aniline have been examined, and the constitution I: 2:4 assigned to the dibromo-aniline. A large section is next devoted to the three isomeric dibromo-benzenes; dichlorobenzene is also considered, and the three monobromo-toluenes. The action of bromine on the isomeric nitro-anilines has been studied, and constitutional formulæ are assigned to the resulting compounds. The author then goes on to consider the preparation of the new dinitrobenzene and the products of its transformations. The mono-nitro compound has been submitted to a similar study, and likewise the mono-nitro derivatives of the dichloro-, chlorobromo-, chloro-iodo-, bromo-iodo-, and di-iodo-benzene. The next section is devoted to the constitution of the principal substitution products of phenol. The isomeric monobromophenols are first treated of, then the following bodies in succession:dibromo-ortho-nitroanisol, the corresponding meta compound, Laurent's bromodinitrophenol, the dinitrochlorophenol of Dubois, and the corresponding bromo- and iodo compounds; finally, dinitro-para-dibromobenzene, its phenol and aniline. The three isomeric tribromobenzenes are next treated of: nitrotribromobenzene and the products of its decomposition. The constitution of the di-derivatives is discussed, and the present state of our knowledge with respect to the ortho-, para-, and meta- series of the aromatic compounds is well displayed in a series of tables. The remainder of this paper, of which the foregoing is but an imperfect outline, is entirely devoted to theoretical considerations.

3

The next paper is a preliminary note on the action of hydriodic acid on santonic acid, by S. Cannizzaro and D. Amato.-This is followed by a paper by the same authors on metasantonine, to which the formula C15H180g is assigned.—Quantitative determination of the atomic group C,H,O contained in acetyl substitution products, by Fausto Sestini.-On the action of bromine on anhydrous chloral, by A. Oglialoro.-Allylate of chloral, by the same author.-Transformation of benzamide into benzoic aldehyde and alcohol, by Prof. J. Guareschi. --Action of sulphur on calcium carbonate, by E. Pollacci.—On the production of ozone by means of the electric discharge, by C. Giannetti and A. Volta. -On the necessity for searching for phosphorus in the urine in cases of poisoning, by F. Selmi. The same author contributes a paper on milk. The concluding paper is by M. Mercadante, on the behaviour of tannic acid when used in agriculture.-The part concludes with notices of current foreign work in technical chemistry.

Bulletin de la Société d'Anthropologie de Paris, tome neuvième.-M. Dareste, in reply to the discussion which his paper on double or twin monsters (as given in a former number) had called forth, explains the nature of the observations on which his deductions were based. It would appear that after submitting nearly 8,000 hens' eggs to the process of artificial incubation, he obtained nearly 4,000 anomalies or monstrosities, but of these only about thirty were double embryos or twin monstrosities. A similar result has been observed in the case of osseous fishes; and Jacobi, who was the first to discover (in the course of the last century) the mechanism of fecundation among these fishes, had noted the proportion of twin monsters in fishes' eggs.

His observations and those of Lerebouillet coincide with the result obtained by M. Dareste, that while external conditions may often determine the formation of simple monsters, they are absolutely without effect in regard to the evolutions of double monstrosities.-M. M. A. Bertrand, in a communication specially addressed to the Society, has propounded the novel hypothesis

that the discovery of the manipulation of metals, as copper, tin, iron, silver, and lead, is due to Oriental peoples, with whom it was far advanced at a period when Europe was still in a state of barbarism. He, moreover, is of opinion that these arts came from a common centre by two channels, viz., the valley of the Dnieper and the valley of the Danube, in the latter of which the semi-barbarous Slavonic tribes still practise these arts very much as they first learned them from their Asiatic neighbours. M. Hamy considers, in a short paper, the value as a distinctive palæontological character of the bifid condition of the canines in the Smeermaas jaw. He had frequently before noticed a transversal flattening in other fossil canines, and since his examination of the Smeermaas jaw he has found two other examples of this from the Quaternary period.-M. Broca discusses at length the influence of humidity on the form and dimensions of fossil crania, and deduces from his observations the general conclusions that the capacity of crania varies greatly in accordance with the hygrometric condition of their walls; that in drying, after removal from a humid soil, they undergo a considerable retraction, amounting in some instances to fully twenty cubic centimetres; that the walls of fossil crania are hygrometric; and that, consequently, no comparative observations of cranial capacity have any value unless all the crania have been exhumed for a space of many months.

THE August number of the Bulletin de la Société d'Acclimatation de Paris opens with a list of the various animals and plants which the society is prepared to lend to its members, with a view to establishing any new or rare forms of animal or vegetable life in different parts of the country. This is an organisation which might usefully be adopted in England. -A paper by M. B. Rico shows how varieties of Salmonida may be kept in enclosed waters, and points out-as Mr. Buckland has proved in England - that salmon and trout will keep in good condition in enclosed places with a good supply of food and of running water.—Dr. Turrel, in a paper entitled "Les Oiseaux et les Insectes," combats the theory of M. Perris that birds have very little effect in checking the increase of insects. He thinks that to the indiscriminate slaughter of small birds may be traced, to a certain extent, the spread of the Phylloxera.-Mr. R. Trimen contributes an interesting paper on the animals and useful plants of the Cape of Good Hope, from which it appears that there are no mammalia indigenous to South Africa which have been employed as beasts of burden; but the colony is rich in edible animals and valuable birds.-M. Cabonnier announces the arrival from India of several specimens of three varieties of fish never hitherto brought to Europe-the Anabas scandens or Climbing Perch, the Telescope Fish, and the Gourami.-The Phylloxera is the object of various notes and suggestions, with the view of providing some means of rresting its progress.

Reale Istituto Lombardo, Rendiconti, vol. 7, fasc. viii.Prof. Giovanni Cantoni contributes a note, "Researches on Heterogenesis." Ten years ago the Academy appointed a committee to investigate spontaneous generation, which from time to time reports its experiments. Dr. Grassi and Dr. Macagno, at Asti, have devoted themselves to the question of vinous fermentation. With saccharine solutions and new wine, they obtained the cryptogams characteristic of vinous fermentation. A certain number appeared in flasks hermetically sealed and heated for half an hour to 100°, and some occurred in flasks containing air filtered through cotton-wool, and washed both in sulphuric acid and an alkaline solution. These observers affirm that raising the temperature of wine does not destroy Pasteur's germs, owing to a special combination between the liquid and the small quantity of free oxygen remaining in the sealed vessel.—The next paper, On the limits of electrical resistance in non-conductors, is by the same author.-Prof. Giovanni Zoga gives an account of the Anatomical Museum of Pavia, which contains 638 preparations, of which 38 are complete skeletons, 26 male and 12 female, varying in age from the foetus of two months to IOI years. Most of them are Italian, though two are German, one American, one Moor, and one Egyptian. There are 200 skulls and 400 portions of different skeletons. Of these skulls only 46 are females, and although the greater part are Italian, they include representatives of the various nations of Europe, Asia, and America, and of different social grades. The author mentions peculiarities seen in the several bones, and gives measurements of the skulls.-The last article is by Dr. Guido Grassi, and is devoted to the explanation of a new reflecting balance. This is a common balance with a reflector fixed above the index. details experiments to show the way in which it may be used,

He

entire or sparsely serrulated. The third and subsequent pairs of leaves partook of the form of the first pair, though seldom so large. It was worthy of remark, that in plants with alternate leaves, the leaves with their axial buds were generally about the same size. In some few instances there were variations in the size, especially in the arrangement of the leaves on the stem. In opposite leaved plants the rule was the other way; one bud or one leaf, either in the blade or petiole, being larger or longer than the other. In the maples this was especially the case. At times the petioles in some cases would be not more than half the length of the opposite. He had found this especial peculiarity, however, in no other species but A. Pennsylvanicum that he had been able to examine, which included most in common cultivation. It might be in A. spicatum, Lam., which he had not been able to examine this season, and which he supposed to be but a variety of A. Pennslyvanicum.

Aug. 25.-Dr. Ruschenberger, president, in the chair.-Prof. Leidy exhibited a living specimen of the freshwater ciliated polyp, formerly described by him under the name of Pectinatella magnifica. Pectinatella is by far the largest of all the known freshwater ciliated polyps, and, indeed, is not surpassed by any of the marine forms known to us. It has not been determined whether the huge Pectinatella colonies start each from a single individual, or are the result of the confluence of a number of small colonies. On the approach of winter the colonies die and undergo decomposition, in which process the remarkable winter eggs or statoblasts are liberated. These are provided with anchor-like spines, by which, as in the case of the eggs of skates and sharks, they become attached to various fixed bodies. In examining various common animals of our household, Prof. Leidy had found a thread-worm infesting the common house-fly. The worm is from a line to the tenth of an inch long, and lives in the proboscis of the fly. It was found in numbers from one to three in about one fly in five. The parasite was first discovered in the house-fly of India, by the English naturalist, Mr. H. J. Carter, who described it under the name of Filaria musca, and suggested the opinion that it might be the source of the Guinea worm, Filara medinensis, in man. Mr. Carter states that he found from two to twenty of the worms in one fly of three. Dr. Diesing referred the parasite to a new genus with the name of Habronema muscæ. The singular position in which the worm lives suggests the many unsuspected places we have to search to find the parents or offspring of our own parasites.

PARIS

The

Academy of Sciences, Nov. 16.-M. Bertrand in the chair. The following papers were read :-On a new class of organic compounds, the carbonyls, and on the true function of ordinary camphor, by M. Berthelot. The author classes as carbonyls the three bodies, ordinary camphor, oxide of allylene, and diphenylacetone.-Action of heat on ordinary aldehyde, by M. Berthelot.-On the carpellary theory according to the Liliaceae and the Melanthaceae, by M. A. Trécul. On wounds from trepanning and their dressing, by M. C. Sédillot.-Observations on the November shooting stars, by M. Leverrier.-On the age of the Pyrenean red sandstone and relationship to the Saint-Béat statuary marble, by M. A. Leymerie.-On electric induction, by M. P. Volpicelli.-Action exercised by an electro-magnet on the spectra of rarefied gases traversed by the electric discharge, by M. J. Chautard. author has hitherto examined only the spectra of metalloids. The magnet appears to influence the number, position, fineness, &c., of the spectral lines in a special manner for each element. -Note on magnetism and on a new exploding fuse, by M. Trève. On the circulatory system of the Echinidæ, by M. Edm. Perrier.-Note on the manufacture of paper from gombo (Hibiscus esculentus), and on the industrial uses of this plant, by M. Ed. Landrin. On the relationship existing between the chemical composition of the air in the swim-bladder and the depth at which the fish are taken, by M. A. Moreau.-Unwholesomeness of the Seine in August, September, and October, 1874, by M. Boudet.-Method pursued in searching for the most efficacious substance for resisting Phylloxera at the viticultural station of Cognac, by M. Max Cornu.-Effects produced by the first frosts on the phylloxerised vines in the vicinity of Cognac, by M. Maurice Girard.-A despatch was read from the French Minister at Pekin, and a letter from M. Fleuriais, announcing the safe arrival and installation of the Transit of Venus Expedition in that city. On two points in the theory of substitutions, by M. C. Jordan.--On fluorene, by M. Ph. Barbier. The formula

for this hydrocarbon is CH10. The author has examined many of its derivatives.-On the marsupium of the eye of birds, by MM. J. André and Beauregard.-New method for the antiseptic occlusion of wounds, by M. Sarazin.-On the mutability of microscopic germs and on the passive function of the organisms classed as ferments, by M. J. Duval.-The carboniferous limestone soil of the Pyrenees, by M. Henri Magnan.-The shooting stars of November 1874, by M. Chapelas.

Nov. 23.-M. Cl. Bernard in the chair.-The following papers were read :-Meridional observations of the minor planets made at Greenwich Observatory (forwarded by Sir G. B. Airy, Astronomer Royal) and at the Observatory of Paris during the third quarter of the year 1874, communicated by M. Leverrier.-M. H. A. Weddell communicated a botanical note on the algolichenic theory.-Note on the gum-bearing Acacia of Tunis, by M. Doûmet-Adanson.-On new improvements in magneto-electric machines, by M. Z. T. Gramme.-On the saccharine matter contained in mushrooms, by M. A. Müntz.-Effects of potassium sulphocarbonate on Phylloxera, by M. Mouillefert.-M. Max Cornu presented a paper containing the continuation of his researches for the most efficacious substance for the destruction of Phylloxera.-Experiments made on branches of vine immersed in water containing various substances in solution, by M. A. Baudrimont.-Facts relating to Phylloxera and to the submersion of vines and cereals; application of M. Naudin's process to vines that cannot be submerged, by M. G. Grimaud.-On the stability of the equilibrium of a heavy body resting on a curved support, by M. C. Jordan.-Influence of temperature on the coefficient of capillary flowing of liquids, by M. A. Gueront.-On the product formed by the addition of hypochlorous acid to propylene, by M. L. Henry. On the Actinia of the oceanic coasts of France, by M. P. Fischer.-New researches on the organogenesis of Lophospermum erubens, by M. Frémineau.-M. E. Duchemin communicated a note concerning the invention of the circular compass. -During the meeting the perpetual secretary announced to the Academy the safe arrival at Sydney of MM. André and Angot, the members of the Transit of Venus Expedition who are to observe this phenomenon from Noumea.

BOOKS AND PAMPHLETS RECEIVED BRITISH.-Report of Newcastle-on-Tyne Chemical Society.-The Aërial World: G. Hartwig (Longmans).-Transits of Venus: R. A. Proctor, B.A. (Longmans).-Descent of Man (New Edition): Charles Darwin, M.A., F.R.S. (J. Murray).-Transactions of the Institute of Engineers and Shipbuilders in Scotland. Report on Safety Valves.-Chambers's Information for the People (W. and R. Chambers).-The Origin of Civilisation and the Primitive Condition of Man: Sir John Lubbock, Bart., M.P., F.R.S. (Longmans).-Elements of Embryology: M. Foster, M. A., M.D., F.R.S., and F. M. Balfour, B.A. (Macmillan and Co.)

AMERICAN.-Relation between the Barometric Gradient and the Velocity of the Wind: Wm. Ferrel, A.M. (Washington, U.S.)-Complete Works of Count Rumford, vol. iii. (Boston, U.S.)-Proceedings of the American Society of Arts and Science (John Wilson, Boston).-Proceedings of the American Philosophical Society (Philadelphia).-Annotated List of Birds of Utah: H. W. Henshaw (Salem, U.S.)-Report of Explorations of 1873 of the Colorado of the West: Prof. J. W. Powell (Washington).-Synopsis of the Flora of Colorado: T. C. Porter (Washington).

FOREIGN.-Correspondenzblatt des Naturforscher-Vereins zu Riga.—Observacions magneticas y Meteorologicas (Havana, Cuba).

THURSDAY, DECEMBER 10, 1874

happens among the unicellular Fungi and Alga (e.g., Mucor, Vaucheria, Caulerpa).

II. The METAZOA are distinguishable, in the first place,

KINGDOM*

LINNÆUS defines the object of classification as

follows:- Methodus, anima scientiæ, indigitat, primo intuitu, quodcunque corpus naturale, ut hoc corpus dicat proprium suum nomen, et hoc nomen quæcumque de nominato corpore beneficio seculi innotuere, ut sic in summa confusione rerum apparenti, summus conspiciatur Naturæ ordo." (Systema Naturæ, ed. 12, p. 13.)

With the same general conception of classificatory method as Linnæus, Cuvier saw the importance of an exhaustive analysis of the adult structure of animals, and his classification is an attempt to enunciate the facts of structure thus determined, in a series of propositions, of which the most general constitute the definitions of the largest, and the most special, the definitions of the smallest, groups.

Von Baer showed that our knowledge of animal structure is imperfect unless we know the developmental stages through which that structure has passed; and since the publication of his "Entwickelungs-Geschichte der Thiere," no philosophical naturalist has neglected embryological facts in forming a classification.

Darwin, by laying a novel and solid foundation for the theory of Evolution, introduced a new element into Taxonomy. If a species, like an individual, is the product of a process of development, its mode of evolution must be taken into account in determining its likeness or unlikeness to other species; and thus " phylogeny" becomes not less important than embryogeny to the taxonomist. But while the logical value of phylogeny must be fully admitted, it is to be recollected that, in the present state of science, absolutely nothing is positively known respecting the phylogeny of any of the larger groups of animals. Valuable and important as phylogenic speculations are, as guides to, and suggestions of, investigation, they are pure hypotheses incapable of any objective test; and there is no little danger of introducing confusion into science by mixing up such hypotheses with Taxonomy, which should be a precise and logical arrangement of verifiable facts.

The present essay is an attempt to classify the known facts of animal structure, including the development of that structure, without reference to phylogeny, and, therefore, to form a classification of the animal kingdom, which will hold good however much phylogenic speculations may vary.

Animals are primarily divisible into those in which the body is not differentiated into histogenetic cells (PROTOZOA), and those in which the body becomes differentiated into such cells (METAZOA of Hæckel).

I. The PROTOZOA are again divisible into two groups: 1. the Monera (Hæckel), in which the body contains no nucleus; and 2. the Endoplastica, in which the body contains one or more nuclei. Among these, the Infusoria ciliata and flagellata (Noctiluca, e.g.), while not forsaking the general type of the single cell, attain a considerable complexity of organisation, presenting a parallel to what * Paper read at the Linnean Society, Dec. 4, 1874, by Prof. Huxley, VOL. XI.-No. 267

Sec. R.S.

which is accompanied by the differentiation of the body wall into, at fewest, two layers, an epiblast and a hypoblast (Gastrea of Hæckel), and those in which no alimentary cavity is ever formed.

Among the Gastreæ, there are some in which the gastrula, or primitive sac with a double wall open at one end, retains this primitive opening throughout life—as the egestive aperture; numerous ingestive apertures being developed in the lateral walls of the gastrula-whence these may be termed Polystomata. This group comprehends the Spongida or Porifera. All other Gastreæ are Monostomata, that is to say, the gastrula develops but one ingestive aperture. The case of compound organisms in which new gastrula are produced by gemmation is of course not a real exception to this rule.

In some Monostomata the primitive aperture becomes the permanent mouth of the animal (Archæostomata).

This division includes two groups, the members of each of which respectively are very closely allied :-I. The Cœlenterata. 2. The Scolecimorpha. Under the latter head are included the Turbellaria, the Nematoidea, the Trematoda, the Hirudinea, the Oligochata, and probably the Rotifera and Gephyrea.

In all the other Monostomata the primitive opening of the gastrula, whatever its fate, does not become the mouth, but the latter is produced by a secondary perforation of the body wall. In these Deuterostomata there is a perivisceral cavity distinct from the alimentary canal, but this perivisceral cavity is produced in different ways.

1. A perivisceral cavity is formed by diverticula of the alimentary canal, which become shut off from the latter (Enterocala).

The researches of Alexander Agassiz and of Metschnikoff have shown that, not only the ambulacral vessels, but the perivisceral cavity of the Echinodermata are produced in this manner; a fact which may be interpreted as indicating an affinity with the Cœlenterates (though it must not be forgotten that the dendrocœle Turbellaria and many Trematoda are truly "cœlenterate"), but does

not in the least interfere with the fundamental blance of these animals to the worms.

1 resem

Kowalewsky has shown that the perivisceral cavity of the anomalous Sagitta is formed in the same way, and the researches of Metschnikoff appear to indicate that something of the same kind takes place in Balanoglossus.

2. A perivisceral cavity, is formed by the splitting of the mesoblast (Schizocala).

This appears to be the case in all ordinary Mollusca, in all the polychatous Annelida, of which the Mollusca are little more than oligomerous modifications, and in all the Arthropoda.

It remains to be seen whether the Brachiopoda and the Polyzoa belong to this or the preceding division. 3. A perivisceral cavity is formed neither from diverticula of the alimentary canal nor by the splitting of the mesoblast, but by an outgrowth or invagination of the outer wall of the body (Epicala).

The Tunicata are in this case, the atrial cavity in them being formed by invagination of the epiblast.