The explanation of the curious phenomenon of S.W. rollers coming in with a N.E. wind followed in due time. They were caused by a typhoon which was blowing between 200 and 300 miles to the south of us, and which recurved in lat. 16° 10′ N. and long. 116° 30' E., according to the observations of Capt. Symington, whose ship, the Northfleet,' was twice caught in it, and who published an account of the Cyclone.

Pratas Island being so small a spot and situated 170 miles from the mainland of China and about 250 from Formosa, it is remarkable that so many land-birds should have found a home there; and the incidents of the two or three days which elapsed during our passage from the reef to the Island of Formosa were particularly interesting, as throwing light upon this circumstance. Steering N.E. for Tacao-con, we experienced a strong head-wind the whole way, that is, the direction of the wind being in a straight line from southern Formosa to Pratas Island. We left the reef on May 3rd, on the 4th a large flock of sandpipers met us going with the wind towards Pratas, where no doubt they would find a resting-place. But the following day, being then a little more than halfway from the reef to Formosa, the rigging was scarcely free at any time during the day from feathered guests, which must have been driven off the Formosa coast by the wind, and some of them at least would have reached Pratas had they not found a resting-place and in some instances a passage back, on board the Serpent.' The following birds I observed at various times during the day, and sometimes several of them flying about the ship, and from time to time lying on various parts of the rigging; a yellow warbler (Sylvia), a yellow wagtail (Motacilla), a shrike (Lanius), grey with a black moustache, apparently identical with the one already seen on the island, two species of swallow (Hirundo), a small heron (Ardea), a very handsome blackbird rather bigger than a common blackbird, with a crimson beak and a large white spot on each wing, a very pretty red dove with a white head, a yellow and black spotted plover, precisely resembling the British golden plover, a species of flycatcher (? Myiagra azurea), and a bird closely resembling a hen chaffinch (? Munia topila).

This interesting assemblage of birds was evidently but a few of the numbers blown off the land (probably Formosa) by the force of a moderately strong N.E. wind, and of them, many would perish in the sea, a few would find relief and restoration in passing ships, and without doubt some would reach Pratas Island, and finding means of subsistence, would take up their residence there, and be jotted down in the Avi-fauna of the next observer.

II. NERVE STRUCTURE AND FORCE.

By HOLMES COOTE, F.R.C.S.,

Of St. Bartholomew's Hospital.

A SUPERFICIAL examination of the earth's crust shows, that from the most remote epochs there has been a succession of animal forms corresponding with the nature of the atmosphere in which such animals were framed to live; also that the transition from sea to estuary, and from estuary to river and thence to dry land, has been slow and without violence; and that among the marine strata there are mingled both animal and vegetable productions belonging to fresh-water life or the inhabitants of dry land. The study of geology therefore embraces not only the structure of the earth, but likewise natural history, comparative anatomy, and the physical sciences generally, and hence proves to its followers a source of endless intellectual enjoyment.

Among the early ideas, which strike us, is the important part played by the invertebrate or lower forms of animals, as compared with the vertebrate, in the history of the revolutions of the globe: through their ceaseless operations, islands are raised in the middle of the ocean, while from their débris such masses as those which constitute our chalk-cliffs are constructed. Whatever may have been the decree of the divine will as to their first creation, they must each in their generations have increased and multiplied until their missions were respectively accomplished. Some inquiry into their nature and organization becomes therefore interesting.

There are two great functions in operation in all forms of animal life, without which the race becomes extinct, namely, alimentation and reproduction. Even in the most complex organisms, such as man, endowed with the highest faculties and capable of the grandest mental efforts, the desire to "eat to live" and the fostering love of offspring constitute the most abiding emotions. In savage life the hunter will endure any amount of fatigue to secure his supply of food, and will fight to the death for the preservation of his young; and so among brute animals, though in a less degree, until, in the more simply organized, the love of self consumes all other feelings under the form of a reflex action of personal wants, and the young are provided for by those mysterious laws whose phenomena we may study, whose source and directing power we can refer only to the "One great Cause."

In the vertebrata, the organs of alimentation consist of a tube with oral and anal aperture; of teeth, to seize and grind; and of numerous accessory glands, such as parotid gland, liver, pancreas, &c. By means of these the nutritive material is prepared, that it may be subjected to other changes, which convert it into blood;

and then come excretory organs, such as the kidneys, to deprive the blood of all noxious principles. But in the invertebrata, the mode of alimentation is often more simple, although we may find the animal supplied with other organs fitted for its own preservation, but not directly for propagation, such as poison-bags, spinning apparatus of spiders, the ink-bag of the cephalopods.

Under most conditions in the animal world the act of reproduction takes place by means of an ovum or egg, which is fecundated by the spermatozoon, a mysterious germ moving about in a peculiar secretion. The organs, therefore, subservient to such functions are the most important. But other modes consist in the act of spontaneous fission or division of the parent animal, or by the act of budding or gemmation.

The young animal which leaves the egg is very often an exact counterpart of the parent, differing only in size, as in the case of the common chick; but in a vast number of instances this resemblance does not exist; sometimes the young require yet further evolution and change; in other cases there is no resemblance at all, either in form or mode of living; and this brood may repeat itself in its dissimilar character, or may again acquire the peculiar organs which bring it back to the parent shape. Then again we have the wellknown metamorphoses as illustrated by the larvae of insects, in which the offspring, though unlike the mother, passes through a definite series of changes, until it again acquires the parent form, again to reproduce in like fashion, and finally to die.

In all animals this function seems under the direction of what, for want of a better term, has been called "vital principle," "nerve power," &c.-not that brain ganglia or nerve fibres can invariably be found-but the changes are such as can hardly be explained on the ground of mere chemical affinity or of nutrition and assimilation.

What have we to say of nerve-power? Viewing it from its lowest manifestation, we may regard it as some dynamic force, evolved and regulated by co-existing, but yet unknown laws. Regarded from its higher attributes, we must incline to a principle of life, which is something superadded to ordinary laws, something which, while it lasts, keeps in abeyance the usual elements of deterioration and decay. Call it what we will, the ; the vital principle; its presence expresses life and creative or constructive action; its absence, decay, dissolution, degradation.

In the lowest forms of animal life, its presence is recognized by no known structure, but we soon observe nerve ganglia and fibres. They first appear about the oral aperture, their fibres extend to the radiating tentacles. The distribution of such nerve fibres and ganglia depends on the form of the individual, so that in myriapoda and annelida, they are repeated at segmental intervals, or concentrated in insecta, where the vitality is most clearly manifested in the head.

But as the higher manifestations of the mind become developed, so we notice that the accumulation of nerve-matter about the head increases; and that moreover there is a distinct line of demarcation between one kind of nerve substance, which is white, and another, which is grey; in other words, between the "nerve generators," or holders, and the "nerve conductors."

In the present communication my object will be to trace the relation between the habits of the animal and the functions performed by its different organs, with the apparent object of its mission. Such an inquiry, embracing the most comprehensive field of natural history, appears to me to exceed, in our day, the capabilities of a single individual; and my remarks must therefore be received only as a partial contribution towards our knowledge on the subject.

In both water and air, the two atmospheres which support animal and vegetable life, nature has provided means for maintaining purity and freshness. The antagonistic influences of animal and vegetable respiration have long been recognized, and similar provisions are made for fresh and salt water. The great sources of impurity in the two latter would proceed from the surface and from the deep, and not from the intermediate strata. On the former, and especially in warm climates, we should find hosts of insect forms; in the latter, multitudes of infusoria, small crustacea, and other denizens of the water.

It is said that if the young gnat were not devoured by fish, water-fowl, &c., the air would become darkened, even in this cold climate, by their immense multitudes. The same remark applies with greater force to the mosquito, each female of which lays annually, on the surface of water, about 300,000 ova. But there are yet other forms, more minute and microscopic, which in summer time may be detected in the spray thrown up by the paddle of the steamboat. What means are provided for keeping within bounds this exuberance of life?

Among the most beautiful appearances presented by the ocean is the silvery phosphorescent light, seen on a summer's night, illuminating the track of every boat and defining the contour of the waves. This subject has been studied by many naturalists, the foremost of whom is M. de Quatrefages, of Paris, whose researches on Noctiluca miliaris are too well known to require comment; and an important addition to our knowledge has also emanated from the labours of Professor Huxley. This luminosity proceeds in the main from living invertebrate animals-Protozoa, Medusa, annelids, crustaceans. Among these the most important part is played by a singular and anomalous creature, of very simple organization, the Noctiluca miliaris just named. This form has been described as a gelatinous transparent body, about of an inch in diameter, having very nearly the form of a peach; where the stalk of the peach

might be, a filiform tentacle, equal in length to about the diameter of the body, depends from it, and exhibits slow wavy motions when the creature is in full activity. The body is composed of a structureless membrane; beneath this there is a layer of granules, or rather, a gelatinous membrane, through whose substance minute granules are scattered without any definite arrangement. From hence arises a network of very delicate fibres. There is an oral aperture, a sort of half oval, with a straight edge anteriorly, and a deeply curved outline posteriorly. From the bottom of the oral cavity a very delicate filament is occasionally protruded, which exhibits a rapid undulating motion, and is then suddenly withdrawn ; doubtless, as suggested by Krohn, who first discovered it, the function is to sweep nutritive matter into the oral cavity. Close to the right extremity of the anterior oral margin, is a horny-looking S-shaped ridge, named by Huxley, a tooth, 1-7000 inch high. The oral aperture leads to the granular mass of the alimentary cavity, from which the fibres and the fibrils radiate.

What purpose now does the luminosity of Noctiluca serve? Passing down the Mediterranean in 1854 I was struck with its brightness and universality on most nights. Is it a voluntary act on the part of the animal, or is it determined only by reflex laws? In the fire-fly (Lampyris Noctiluca) it serves for the attraction of the sexes, and can be extinguished and renewed as the animal pleases. In Noctiluca miliaris, its purpose must be for the attraction of its minute prey: the oral aperture, its tongue and teeth all point to the fact that the animal is carnivorous, and serves to keep down those still more minute animal forms, which might otherwise render the water in which they live and generate, impure. But no distinct nervous system has here been traced.

Another class of marine animals, also carnivorous, the Actiniæ, live among rocks and broken surfaces, where they perform a similar purifying function, by the destruction of animals of larger form and of apparently much greater power than they themselves possess. But in these, as in the preceding, no trace of nerve matter can be clearly found, and yet they exhibit a power of selection which gives evidence of sense. If a young actinia be put within the tentacles of a larger individual, that fatal grasp is withheld, while a young crab or prawn is promptly seized and devoured. Its migra tions, though slow, have usually some definite purpose; it avoids bright light, preferring the shelter of a piece of rock; it requires air, and will hang, tentacles downward, for hours from the surface of the water, floating by means of an air-bladder of its own formation.

Near the oral aperture we often see a series of bright spots, called Ocelli; they are not always present, and are subject to change of colour-are brighter at some times than at others. They have been considered by some as organs of vision placed on nerve ganglia,