been completely washed out of it on its way to the surface. The bottom water gave a specific gravity of 102504 at 19°6 C., that of the surface being 102617 at 21°3 C. While sounding, the current-drag was tried, and indicated a slight north-westerly current.

As the attempt to dredge on the previous day had been unsuccessful, it was determined to repeat the operation with every possible precaution on the 26th. The morning was bright and clear, and the swell, which had been rather heavy the day before, had gone down considerably. A sounding was taken about 10 o'clock A M. with the "Hydra" machine and 4 cwt. The sounding was thoroughly satisfactory, a sudden change of rate in the running out of the line indicating in the most marked way when the weight had reached the bottom. During the sounding a current-drag was put down to the depth of 200 fathoms, and it was then ascertained that, by means of management and by meeting the current by an occasional turn of the screw, the ship scarcely moved from

her position during the whole time the lead was running out. The depth was 3,150 fathoms; the bottom a perfectly smooth red clay, containing scarcely a trace of organic matter-merely a few coccoliths, and one or two minute granular masses. The thermometer indicated a bottom temperature of 1° 9 C.

The small dredge was sent down at 2.15 P.M. with two hempen tangles; and, in order to ensure its reaching the bottom, attached to the iron bar below the dredge which is used for suspending the tangles, a " Hydra" instrument with detaching weight of 3 cwt. Two additional weights of I cwt. each were fixed to the rope 200 fathoms before the dredge. 3,600 fathoms of rope were payed out-1,000 fathoms 2 in. in circumference, and the remainder (2,600 fathoms) 2 in. The dredge came up at 10.15 P.M. with about I cwt. of red clay.

This haul interested us greatly. It was the deepest by several hundred fathoms which had ever been taken, and, at all events coincidentally with this great increase in

depth, totally different from what we had been in the habit of meeting with in the depths of the Atlantic. For a few soundings part of the ooze had been assuming a darker tint, and showed on analysis a continually lessening amount of calcareous matter, and, under the microscope, a smaller number of foraminifera. Now calcareous shells of foraminifera were entirely wanting, and the only organisms which could be detected after washing over and sifting the whole of the mud with the greatest care, were three or four foraminifera of the Cristellarian series, with their tests made up of particles of the same red mud. The shells and spines of surface animals were entirely wanting; and this is the more remarkable as the claymud was excessively fine, remaining for days suspended in the water, looking in colour and consistence exactly like chocolate, indicating therefore an almost total absence of movement in the water where it is being deposited. When at length it settles, it forms a perfectly smooth redbrown paste, without the least feeling of grittiness between the fingers, as if it had been levigated with extreme care

for a process in some refined art. On analysis it is almost pure clay, a silicate of alumina and the sesquioxide of iron, with a small quantity of manganese.

It is of course a most interesting question whether the peculiar nature of this deposit is connected in any way with the extreme depth. I am certainly inclined at present to believe that it is not. The depth at Station 5 was 2,740 fathoms, and on that occasion foraminifera were abundant, and several bivalve mollusca were taken living. I cannot believe there can be any difference between a depth of 2,740 fathoms and one of 3,150 so essential as to arrest the life of the organisms to the secretions of whose tests the grey Atlantic ooze is due. I am rather inclined in the meantime to attribute this peculiar deposit to the movement of water from some special locality-very possibly the mouths of the great South American rivers-the movement possibly directed in some measure by the form of the bottom. This, however, is a question for the solution of which we may hope to procure sufficient data. WYVILLE THOMSON

31

INSECTS* III.

thoracic legs; those which feed on leaves have the thoracic legs more developed, but less so than the carnivorous species. Now, the Hymenoptera, as a general rule,

mons, &c., which live in animals,—those of the Cynipida, which inhabit galls, and those of ants, bees, wasps, &c., which are fed by their parents, are all fleshy, apodal grubs. On the other hand, the larvæ of Sirex, which are wood-burrowers, quit the type which is common to the majority of the order, and remain in the egg until they have developed small thoracic legs. Again, the larvæ of the Tenthredinidæ, which feed upon leaves, closely

FIG. 1. Larva of the Cockchafer (Melolontha). (Westwood. Int. to the Modern Classification of Insects, v. 1., p. 194) 2, Larva of Cetonia, 3, Larva of Trox. 4, Larva of Oryctes. 5, Larva of Aphodius. (Chapuis and Candeze, Mem Soc. Roy. Liege, 1853. 6, Larva of Lucanus. (Packard, "Guide to the Study of Insects," Fig. 403).

If, again, we take a group, such, for instance, as the Lamellicorn beetles, we shall find larvæ extremely similar in form, yet very different in habits. Those for instance of the common cockchafer (Fig. 1) feed on the roots of grass, those of Cetonia aurata (Fig. 2) are found in ants' nests; the larvæ of the genus Trox (Fig. 3) on dry animal substances; of Oryctes (Fig. 4) in tan-pits: of Aphodius (Fig. 5) in dung; of Lucanus (the stag-beetle, Fig. 6) in wood.

FIG. 7, Larva of Brachytarsus (Ratzeburg, Forst Insecten). 8, Larva of Crioceris (Westwood, l.c.) 14, Larva of Sirex (Westwood 1.c.) 15. Egg of Rhynchites, showing the parasitic larva in the interior. 16, the parasitic larva more magnified.

resemble the caterpillars of Lepidoptera, even to the little variety in this respect, some species having eleven presence of abdominal prolegs. There is, however, some pairs, some ten, some nine, while the genus Lyda has only the three thoracic pairs.

and more or less flattened: but on the other hand with Again, the larvæ of beetles are generally active, hexapod, the weevils, they are apod fleshy grubs, like those of those species which live inside vegetable tissues, such as Hymenoptera. Pl. 2, Fig. 6, represents the larva of

FIG. 9, Larva of Sitaris humeralis. (Fabre, Ann. d. Sci. Nat. Ser. 4. vol. vii.) 10, Larva of Sitaris humeralis, in the second stage. 11, Larva of Sitaris humeralis, in the third stage. 12, Larva of Sitaris humeralis, in the fourth stage. 13, Pupa of Sitaris.

In the present chapter it will be my object to show that the form of the larva depends also very much on its mode of life. Thus, those larvæ which are internal parasites, whether in animals or plants, belong to the vermiform state; and the same is the case with those which live in cells, and depend on their parents for food. On the other hand, larvæ which burrow in * Continued from vol. vii. p. 489.

FIG. 17, Egg of Platygaster (after Ganin). 18, Egg of Platygaster showing the central cell. 19, Egg of Platygaster after the division of the central wall 20, Egg of Platygaster more advanced. 21, Egg of Platygaster more advanced. 22, Egg of Platygaster showing the rudiment of the embryo.

the nut-weevil, Balaninus (Pl. 1, Fig. 6), and it will be seen that it closely resembles Pl. 2, Fig. 5, which represents that of a fly (Anthrax), Pl. 1, Fig. 5, and Pl. 2, Figs. 7, 8, and 9, which represent respectively those of a Cynips or gall-fly (Pl. 1, Fig. 7), an ant (Pl. 1, Fig. 8), and wasp (Pl. 1, Fig. 9). Nor is this the only group of Coleoptera which affords us examples of this fact. Thus in the genus Scolytus (Pl. 1, Fig. 4), the larvæ (Pl. 2, Fig. 4),

23

which, as already mentioned, feed on the bark of the elm, closely resemble those just described, as also do those of Brachytarsus (Fig. 7). On the other hand the larvæ of certain beetles feed on leaves, like the caterpillars of Lepidoptera; thus the larva of Crioceris Asparagi (Fig. 8), which, as its name denotes, feeds on the asparagus, closely resembles that of certain Lepidoptera, as for instance of Thecla spini. A striking illustration of this is afforded by the genus Sitaris (Pl. 3, Fig. 4), a small beetle allied to Cantharis, the blister-fly, and Meloe, the oil-beetle. The habits of this species have been very carefully investigated by M. Fabre.*

The genus Sitaris is parasitic on Anthophora, in the galleries in which it lays its eggs. These are hatched at the end of September or beginning of October; and M. Fabre not unnaturally expected that the young larvæ, which, as already mentioned, are active little

FIG. 23, Larva of Platygaster (after Ganin-mo, mouth; a, antenna; kf, hooked feet; r, toothed process; fg, lateral process;f, branches of the tail. 24, Larva of another species of Platygaster. The letters indicate the same parts as in the preceding figure. 25, Larva of a third species of Platygaster. The letters indicate the same parts as in the preceding figures. 6, Larva of Platygaster in the second stage-mo, mouth; slk, esophagus; gsae, supra oesophagal ganglion; m, muscles; bsm, nervous system; gagh, rudiments of the reproductive glands. 27, Larva of Platygaster in the third stage-mo, mouth; md, mandibles; g sae, supra-oesophagal ganglion; sik, oesophagus; ag, ducts of the salivary glands; b'n m, ventral nervous system; sp, salivary glands; ms, stomach; im, imaginal discs; tr, trachea; fk, fatty tissue; ed, intestine; ga, rudiments of reproductive organs; ew, wider portion of intestine; a o, posterior opening.

creatures with six serviceable legs (Fig. 9), would at once eat their way into the cells of the Anthophora. No such thing till the month of April following they remain without leaving their birth-place, and consequently without food; nor do they in this long time change either in form or size. M. Fabre ascertained this, not only by examining the burrows of the Anthophoras, but also by direct observation of some young larvæ kept in captivity. In April, however, his specimens at last threw off their long lethargy, and hurried anxiously about their prisons. Naturally inferring that they were in search of food, M. Fabre supposed that this would consist either of the larvæ or pupæ of the Anthophora, or of the honey with which it stores its cell. All three were tried without * Ann. das. Sc. Nat. V. vii. T. 4. See also Natural History Review, April 1862.

success.

The two first were neglected, and when placed on the latter the larvæ hurried away, or perished in the attempt, being evidently unable to deal with the sticky substance. M. Fabre was in despair: "Jamais experience," he says, "n'a éprouvé pareille déconfiture. Larves, nymphes, cellules, miel, je vous ai tous offert; que voulez-vous donc, bestioles maudites?" The first ray of light came to him from our countryman, Newport, who ascertained that a small parasite found by Léon Dufour on one of the wild bees, and named by him Triungulinus, was, in fact, the larva of the Meloe. The larvæ of Sitaris much resembled Dufour's Triungulinus; and acting on this hint, M. Fabre examined many specimens of Anthophora, and at last found on them the larvae of his Sitaris. The males of Anthophora emerge from the pupæ before the females, and he ascertained that as they come out of their galleries, the little larvæ fasten upon them. Not, however, for long: their instinct teaches them that they are not yet in the straight path of development; and, watching their opportunity, they pass from the male to the female bee. Guided by these indications, M. Fabre examined several cells of Anthophora: in some, the egg of the Anthophora floated by itself on the surface of the honey; in others, on the egg, as on a raft, sat the still more minute larva of the Sitaris. The mystery was solved. At the moment when the egg is laid, the Sitarislarva springs upon it. Even while the poor mother is carefully fastening up her cell, her mortal enemy is beginning to devour her offspring. For the egg of the Anthophora serves not only as a raft, but as a repast. The honey, which is enough for either, would be too little for both; and the Sitaris, therefore, in its first meal, relieves itself from its only rival. After eight days the egg is consumed, and on the empty shell the Sitaris undergoes its first transformation, and makes its appearance in a very different form as shown in Fig. 10.

The honey which was fatal before is now necessary; the activity which before was necessary, is now useless; consequently, with the change of skin the active, slim larva changes into a white, fleshy grub, so organised as to float on the surface of the honey, with the mouth below, and the spiracles above the surface; "grâce à l'embonpoint du ventre," says M. Fabre, "la larve est à l'abri de l'asphyxie." In this state it remains till the honey is consumed; then the animal contracts, and detaches itself from its skin, within which the other transformations take place. In the next stage, which M. Fabre calls the pseudo-chrysalis (Fig. 11), the larva has a solid corneous envelope and an oval shape, and in its colour, consistency, and immobility reminds one of a Dipterous pupa. The time passed in that condition varies much. When it has elapsed, the animal moults again, and again changes its form, and assumes that shown in Fig. 12; after this it becomes a pupa (Fig. 13) without any remarkable peculiarities; and finally, after these wonderful changes and adventures, in the month of August the perfect Sitaris (Pl. 3, Fig. 4) makes its appearance.

d. On the other hand, there are cases in which larvæ "iverge remarkably from the ordinary type of the group to which they belong, without, as it seems in our present imperfect state of information, any sufficient reason.

Thus the ordinary type of Hymenopterous larvæ, as we have already seen, is a fleshy apod grub; replaced however in the leaf-eating and wood-boring groups, Tenthredinidæ and Sirecida (Fig. 14) by caterpillars, more or less closely resembling those of Lepidoptera. There is, however, a group of minute Hymenoptera, the larvae of which reside within the eggs or larvæ of other insects. It is difficult to understand why these larvæ should differ from those of Ichneumons, but as will be seen by the accompanying figures, they assume very remarkable and grotesque forms. The first of these curious larvæ was observed by De Filippi,*

* Ann, and Mag. Jof Nat. His., 1852.

who had collected some of the transparent ova of Rhynchites betuleti and to his great surprise found more than half of them attacked by a small parasite, which proved to be the larva of a minute Hymenopterous insect belonging to the Pteromalidæ. Fig. 15 shows the egg of Rhynchites, with the parasitic larva, which is represented on a larger scale in Fig. 16. Recently, however, this group has been more completely studied by M. Ganin,* who thus describes the development of Platygaster. The egg, as in other allied hymenopterous families, for instance in Cynips, is elongated and club-shaped (Fig. 17). After a while a large nucleated cell appears in the centre (Fig. 18); this is a new formation not derived from the germinal vesicle. This nucleated cell divides (Fig. 19) and subdivides. The outermost cells continue the same process, thus forming an outer investing layer. The central one, on the contrary, enlarges considerably, and develops within itself a number of daughter cells (Figs. 20 and 21), which gradually form themselves into a mulberry-like mass, thus giving rise to the embryo (Fig. 22).

Ganin met with these larvæ in those of a small gnat, Cecidomyia. Sometimes as many as fifteen parasites occurred in one host, but as a rule only one attained maturity. The three species of Platygaster differed considerably in form, as shown in the three following Figs. (23-25). They creep about in the egg by means of the strong hooked feet, kf, somewhat aided by movements of the tail. They possess a mouth, stomach, and muscles, but the nervous, vascular, and respiratory systems do not make their appearance until later. After some time the larva changes its skin and assumes the form represented in Fig. 26. In this moult the last abdominal segment of the first larva is entirely thrown off: not merely the outer skin as in the case of the other segments, but also the hypodermis and the muscles. This larva, as will be seen by the figure, is in the form of a barrel or egg, and 870 mm. in length, the external appendages having disappeared, and the segments being indicated only by the arrangement of the muscles; slk fis the esophagus leading into a wide stomach which occupies nearly the whole body, sgs ae is the rudiment of the supracesophagal ganglia, bsn the ventra nervous_cords. The ventral nervous mass has the form of a broad band, with straight sides; it consists of embryonal cells, and remains in this undeveloped condition, during the whole larval state.

At the next moult the larva enters its third state, which, however, as far as the external form (Fig. 27) is concerned, differs from the second only in being somewhat more elongated. The internal organs, however, are much more complex and complete. The trachea have made their appearance, and the mouth is provided with a pair of mandibles. From this point the metamorphoses of Platygaster do not appear to differ materially from those of other Hymenoptera.

An allied genus, Polynema, has also very curious larvæ. The perfect insect is aquatic in its habits, swimming by means of its wings; flying, if we may say so, under water. It lays its eggs inside those of Dragon flies; and the larva, as shown in Fig. 28, leaves the egg in the form of a bottled-shaped mass of undifferentiated embryonal cells, covered by a thin cuticle, but without any trace of further organisation. Protected by the egg shell of the Dragon fly, the young Polynema is early able to dispense with its own; and bathed in the nourishing fluid of the Dragon fly's egg, it imbibes nourishment through its whole surface, and increases rapidly in size. The digestive canal gradually makes its appearance, the cellular mass forms beneath the original cuticle a new skin, distinctly divided into segments, and provided with certain appendages. After a while the old cuticle is thrown off, and the larva gradually assumes the form shown in Fig. 29. asch are the antennal discs, or * Zeits f. Wiss. Zool., 1869.

rudiments of the antennæ, flsch of the wings, bsch of the legs, ufg are lateral projections, gsch of the ovipositor, &c, fk is the fatty tissue. The subsequent metamorphoses of Polynema offer no special peculiarities.

From these facts-and, if necessary, many more of the same nature might have been brought forward-it seems to me evident that while the form of any given larva depends to a certain extent on the group of insects to which it belongs, it is also greatly influenced by the external conditions to which the animal is subjected; that it is a function of the life which the larva leads and of the group to which it belongs.

The larvæ of insects are generally regarded as being nothing more than immature states-as stages in the development of the egg into the imago; and this might more especially appear to be the case with those insects in which the larvæ offer a general resemblance in form and structure (excepting of course so far as relates to the wings) to the perfect insects. Nevertheless we see that this would be a very incomplete view of the case The larva and pupa undergo changes which have no relation to the form which they will ultimately assume. general tendency, as regards size and the production of wings, to this goal, there are combined other changes bearing reference only to their existing wants and condition. Nor is there in this, I think, anything which need

With a

vfg

ysch

FIG. 28. Embryo of Polynema (after Ganin). 29, Larva of Polynema, asch, rudiments of the antenna; fisch of the wings; bsch of the eggs; fg, lateral projections; gscht, rudiments of the ovipositor; fk, fatty tissue.

surprise us. External circumstances act on the insect in its preparatory states, as well as in its perfect condition. Those who believe that animals are susceptible of great, though gradual, change through the influence of external conditions, whether acting, as Mr. Darwin has suggested, through natural selection, or in any other manner, will see no reason why these changes should be confined to the mature animal. And it is evident that creatures which, like the majority of insects, live during different parts of their existence in very different circumstances, may undergo considerable changes in their larval organisation, in consequence of forces acting on their larval condition; not, indeed, without affecting, but certainly without affecting to any corresponding extent, their ultimate form.

I conclude, therefore, that the form of the larva in insects, whenever it departs from the original vermiformor the later Campodea-type, depends in great measure on the conditions in which it lives. The external forces acting upon it are different from those which affect the mature form; and thus changes are produced in the young, which have reference to its immediate wants, rather than to its final form.

And, lastly, as a consequence, that metamorphoses may be divided into two kinds, developmental and adaptional.

NOTES

THE following are the names of the fifteen candidates who have been selected by the Council of the Royal Society, for election this year into that body:-William Aitken, M.D., Sir Alexander Armstrong, M.D., K. C.B., Robert Stawell Ball, LL.D., John Beddoe, M.D., Frederick Joseph Bramwell, C.E., Staff-Captain Edward Kilwick Calver, R.N., Robert Lewis John Ellery, F. R. A.S., Lieut.-Col. J. Augustus Grant, C. B., C.S.I., Clements Robert Markham, C.B., George Edward Paget, M.D., George West Royston Pigott, M.D., Osbert Salvin, M. A., The Hon. John William Strutt, M.A., Henry Woodward, F.G.S., James Young, F.C.S.

THE University of Cambridge has accepted the offer made by Dr. Anton Dohrn of the Zoological Station at Naples, through Dr. Michael Foster and Prof. Newton, of a working table in the laboratory of the station; and last week, on the recommendation of the Board of Natural Sciences, a grace passed the senate without opposition to the effect that from the Worts Travelling Bachelors' Fund the sum of 100l. per annum be granted for three years, for the purpose of securing to such members of the University, as the Board shall from time to time nominate, facilities of studying in the station.

WITH reference to a short article entitled "Survival of the Fittest," in NATURE, vol. vii. p. 404, Prof. L. Agassiz writes us that the observations therein attributed to him are taken from an unauthorised newspaper report, from which we infer that he disclaims them.

WITH reference to our report of the American Philosophical Society for August 16, 1872 (NATURE, vol. vii. p. 335), Prof. Cope writes that we have been misinformed as to the date at which his communication on the discovery of Proboscidia in the Wyoming Eocene was communicated to the Society. The paper was not announced to the Society till its meeting on September 20, and was not published till February 6, 1873.

MR. PENGELLY writes us that the specimens referred to by Mr. Everett (NATURE, April 17) did reach him through Mr. Everett's mother, and were duly acknowledged. The labels were rotten with wet, and the specimens consisted of shells and bones, the latter including human teeth and portions of a skull, incisors of some rodent, and a large hog-like molar.

Plans

PENIKESE ISLAND, the gift of which for the study of natural history to Prof. Agassiz by Mr. Anderson we have already more than once spoken of, was handed over by the donor on Monday, April 21, in a very simple way, accompanied by some speechmaking. Prof. Agassiz and his generous admirer then met for the first time, and for the first time Agassiz set foot on the future sphere of his labours. The short deed of conveyance was read and handed over, and Prof. Agassiz briefly returned thanks, announcing that he intended to christen the institution to be founded on the island, "The Anderson School of Natural History." Preparations for the school, which will open this summer, will be immediately commenced. have already been drawn for a two-story wooden building Ico ft. long and 25 ft. wide. The lower floor is intended for laboratories and working-rooms, of which there will be eight, with a large hall. The second story will contain twenty-six sleeping-rooms, two bath-rooms, and a large room for the Superintendent of the Institution. Several friends of Mr. Anderson in New York have become interested in the school, and will probably give liberally towards its endowment. The island of Penikese, Penekese, or Penequese, and often called Pune by the pilots, is one of a group of the Elizabethan Isles, lying between Buzzard's Bay and Vineyard Sound, and stretching southward from Cape Cod to a point nearly opposite the coast of Rhode Island. Penikese is just inside and on starboard hand of the

entrance to Buzzard's Bay. It is twelve miles from New Bedford. The island is three-fourths of a mile long and half a mile wide, and contains ninety-seven acres of land, some of which is of good quality. A young tree was pointed out that had grown in one season higher than anybody in the party could reach. The surface is hilly, the highest point being about a hundred feet above the water. Mr. Anderson reserves a peninsula of some fifteen acres on the east end of the island, and here he proposes to build a house next year. Prof. Agassiz states that Penikese is a much better location for the school than the one originally contemplated at Nantucket. The school is to be devoted mainly to the study of fish and marine objects in the summer season, and a much larger variety is found in Penikese. The Sound and waters in the vicinity of Nantucket have almost invariably a sandy bottom, while the diversity in marine topography in Buzzard's Bay invites and fosters a corresponding variety of animal and vegetable life.

AT the meeting of the Iron and Steel Institute recently held in London, Mr. Lowthian Bell was elected president, and delivered a very interesting address. He pointed out the great success which had attended the organisation of the society, which although only in the fifth year of its existence, now numbered on its rolls 522 members. He expressed his opinion that the Institute had far from reached its limits. Referring then to the instances which still exist here and there, of a disregard for scientific inquiry, the result, perhaps, of considerable success effected independently of philosophical research, in which cases practical experience, as it is called, is the only rule admitted, Mr. Bell remarked, that on the other hand, abstract science, correct as it may be in every step employed in its elaboration, when introduced into the workshop may be found unable to stand the rude but inevitable test of commercial practicability; hence the necessity of a convenient method of effecting a sound union between these two great principles, and to obtain this was the object of the organisation of the Iron and Steel Institute, where are brought face to face men, some distinguished for their practical knowledge, and others equally eminent for their attachments to scientific observation. He then proceeded to consider the present aspect of foreign competition, and thought the progress in other countries in iron manufacture had arisen from an adaptation of our own appliances, and not from any important discoveries abroad. In speaking of the recent scarcity of coal, although it was his impression that an important addition can and will be made to their present output, he yet contemplated the possibility of a time being now approaching when 'any extension of manufacturing operation in this country would have to be regulated, not by the requirements of society for their produce, but by the means our coal mines might possess of furnishing the fuel required. Mr. Bell, after referring to several improvements in the plant and processes for manufacturing iron, looking forward to the future, expressed his opinion that, unless new discoveries of coal be made in Europe, the great rival we have to fear in the iron manufacture is the United States, which possesses unlimited quantities of ores of the finest quality, and such enormous deposits of coal, that our own wealth in that mineral is but comparative poverty. At the proceedings on April 30, a paper by Dr. C. William Siemens, "On the Manufacture of Iron and Steel by Direct Process, was read. Dr. Siemens described his rotative regenerative gas furnace.

A SPECIAL meeting of the Council and Natural History Committee of the Asiatic Society was held at Calcutta a few weeks since, for the purpose of considering Mr. Schwendler's scheme for the establishment of a Zoological Garden in Calcutta. After considerable discussion it was resolved that the Council of the Society should once more record their opinion as to the great advantage to Natural History Science, as well as to the public