Praslin. Its palms are either male or female, and our examination of more than 300 of its nuts showed that they are of two distinct, structurally different forms in approximately equal proportions, both kinds growing on the same female tree. The case is, so far as I know, unique.

Of the land animals we did not attempt to collect the birds, as they were already sufficiently known. Moreover, most of the peculiar Seychelles species would seem to have been nearly, if not entirely, destroyed by paid collectors. The Government of the Seychelles has, however, promised an ordinance to hinder further destruction. The introduced birds do not belong to the jungle, where, indeed, land birds are seldom seen. Mammals are represented by rats, mice, and bats, and the tenrec runs wild everywhere. Of reptiles we obtained about eleven species of lizards and three snakes. The crocodile would once seem to have been a regular inhabitant, but the last was killed about seventy years ago. Three of the apparently four species of frogs occur at any elevation, but the fourth is peculiar to the high jungles. Cæcilians are numerous, the one genus being an earth burrower, and the other lying under damp leaves in the jungles. Mollusca were represented among the indigenous vegetation by twenty-five to thirty species, including two slugs, and we obtained a fair variety of insects and arachnids. Isopods were numerous everywhere, but centipedes and millipedes were scarce on the high lands, and seemed to consist of species peculiar to them. We carefully searched for Peripatus, but do not think it exists in the archipelago. Land worms were scarce; one species was peculiar in living within the bases of the screw pine leaves, even 40 feet to 50 feet above the ground. We obtained no land leeches or Turbellarians, but found two species of Nemerteans at about 2000 feet.

The fresh-waters consist of certain pools near the sea and a large number of tiny mountain streams, which become roaring torrents in the wet season, but never dry up. In a pool at La Digne we obtained one tortoise with hinged plastron, and in the streams there were four species of fish. The Crustacea comprise at least two species of prawn and a crab, all living up to more than 2000 feet. The Mollusca number only three, and for the rest there were the usual genera of fresh-water insects, &c.

means

The number of species of land and fresh-water animals would on the whole appear to be singularly few, and individuals were, with a few exceptions, by no abundant. Their small variety may be due to the comparatively few plants which grow in the islands, but one is inclined to question the former connection of the group with any larger land mass. In any case, our work has made certain that the archipelago has been sufficiently collected for a thorough examination into this question from a biological point of view. It is our opinion, however, that such a research should include both animals and plants considered together. In any case, the Seychelles is the continuation of a broken line extending north from Madagascar, and its rock would seem to be similar to that which forms the great central plateau of that island.

Since I returned to England I have received a letter from Commander Boyle Somerville giving the soundings obtained by H.M.S. Sealark on her return from the Seychelles. to Ceylon He has confirmed by additional soundings the complete separation of the 2000-fathom lines of the Chagos, Maldive, and Seychelles groups. I have also heard from Mr. D. Matthews that he has obtained about 1000 samples of sea-water from the Indian Ocean during the last nine months, and analysed about 700. Bainbrigge Fletcher, H.M.S. Sealark, reports that a considerable number of the Chagos Lepidoptera appear to be new species or varieties.

Mr.

J. STANLEY GARDINER. Zoological Laboratory, Cambridge, January 15.

What Causes the Destructive Effects of Lightning? I ENCLOSE a cutting from the Hampstead and Highgate Express (January 20) containing an epitome of a lecture which I lately gave at the local scientific society on a case of death by lightning which occurred on the Heath in the month of July last.

I discussed, amongst other matters, the question as to how the more destructive effects of lightning were produced, and now my object in writing to NATURE is to ask

you, Sir, or any of your readers, if you can inform me whether this question has been solved in any probable manner. In the case of the death of an animal from lightning I think we may safely rest on the word electricity as sufficient, for it is not difficult to understand how this form of energy when let loose in the organism of an animal should not only disturb the equilibrium of the machinery, but actually stop it. But the word electricity does not seem sufficient to account for the more destructive effects produced by lightning, which closely resemble those which arise from other well known allied forces. Heat certainly is produced, as we see by the burning of the flesh and by its effects on metals, but as regards the destruction of trees, buildings, and other imperfect conducting substances, the forces seem to be of an explosive character, as are mentioned in the accompanying extract from my lecture.

"The subject which was of most interest to the lecturer was the nature of the destructive agency of the lightning flash, and the present fatal case he thought threw a considerable light upon it. Of course, there was no difficulty in understanding how an electric shock can kill an animal suddenly by bringing the machinery to a stop, when it is considered how fearfully and wonderfully we are made, and that vital processes are at work in every part, when a violent electric shock comes and arrests all these at once. But it is not so easy to perceive how all the more marked and mechanically destructive processes occur, such as the splitting of the timbers in the hut or tearing off the clothes. The destructive effect seemed to be exactly of the kind which follows explosions of gunpowder and kindred substances. This could only occur through a gas being suddenly formed; but whether this would be the production of the vaporisation of a liquid or the formation of some new conditions of the atmosphere by the electricity itself cannot at present be determined. The first object struck by the lightning was the finial, and this was split into numbers of pieces in the direction of the grain of the wood, and the same effect was seen on all the upright posts down which the lightning ran; but, midway across the middle of the hut was a transverse beam, through which the flash passed. At this spot about a foot of the wood was torn off, but in a transverse or horizontal direction in the course of the grain. If a chisel had been driven into the cross beam it would have broken the wood exactly in the same manner; or, indeed, any other force acting on the middle of the splintered wood as an explosive. The coat, and more especially the shirt, showed the explosive force which had produced the rents still better. Although the rents ran down the arm, they had no appearance as if done by an instrument, but rather by a violent pull exerted from side to side, for not only was there one large rent, but similar partial ones running parallel to it. These could only have been done by forcibly stretching from within; in fact, the only way suggested would be an explosion of gas taking place in the shirt sleeve, and so forcibly thrusting it out, causing the fibres of the fabric to give way. The split boot, which was nearly off the foot of the child, could not be imitated except by placing a charge of dynamite within it."

Not professing to have much knowledge of what has been written on the modes and causes of the great destruction caused by lightning, I am writing to obtain more information on the subject. SAMUEL WILKS. January 20.

projection eastward of Ross Island and the peaks called by Ross the Parry Mountains, which were all regarded as part of the mainland, suggested that behind Ross's ice-sheet the mountains of Victoria Land trend to the east. Captain Scott tells us that the Parry Mountains do not exist; but a group of islands, White Island, Black Island, and Minna Bluff, occur in almost the same relation to Mounts Erebus and Terror as Ross marked his Parry Mountains. Behind this archipelago there is a great bight, the land first trending somewhat westward, and bending to the east after about 81° S. Thence, so far as Captain Scott could see, the land has an average trend to S.S.E. from Mount Wharton to the most distant southern peak observed beyond Mount Longstaff. Captain Scott concludes that the mountains continue in the same direction to Graham's Land.

slope southward to the Pole and across it northward to the Atlantic." This view is fully supported by Captain Scott's opinion that, according to his view of the course of the main mountain chain, "the geographical pole would be situated 200 miles more from it, and on the high ice-plateau which must continue behind" (vol. ii. p. 427).

The lands, problematical and proved, to the south of the Pacific probably belong to one of those island festoons, which are still so characteristic, and apparently once occurred along all the Pacific coasts. The only objection to placing the main coastline of the South Pacific south-west of Ross's ice-sheet, instead of along a line north-eastward through King Edward Land, is the ice-barrier, on Captain Scott's theory of its formation. If it be land ice, and be flowing rapidly northward, a mile in three years, it

There is nothing a priori improbable in the connection of Victoria Land and Graham's Land along this line; for coasts of the Pacific type are characteristically straight for long distances, and have broad open curves rather than sudden bends.

This does not affect the essential part of my suggestion made in NATURE, April 25, 1901, "that we may expect the greatest elevations on the Antarctic Lands will lie along the Graham's Land-Victoria Land line, and will be near the sea. To the south of the main mountain range there may be an undulating icecovered region descending slowly across the Pole to the shore of the Weddell Sea. The main ice drainage would then be not from the Pole radially in all directions; the ice-shed would run along the Pacific Shore with a short steep northern face and a long gradual

must be fed from snow-fields among mountains to the south, and is probably confined between high lands to east and west.

It is here that we feel most the need of more precise information regarding the ice of Ross's icesheet, as Ferrar proposes it should be re-named. That this ice is land ice flowing out to sea has been the generally accepted explanation of the facts described by Ross. The difficulty presented by Ross's icesheet, if it be advancing northward along its whole face at anything like the rate of the ice movement round Minna Bluff, is that its surface appears to be practically level, so far as it was followed by Royds to the south-east and by Scott to the south. Hence its rapid movement cannot be due to flow down a slope as in the case of ordinary glacier ice. The best

photograph of the ice (vol. i., p. 192) shows that it is very regularly stratified, and there is no visible interglacial material; the ice appears very different from that typical of glaciers. A photograph of a block of the barrier ice, of which the structure had been brought out by throwing over it a bucket or two of hot water, would have been very useful. The characters of glacier ice are so distinctive that any precise information as to the structure of the barrier ice would have left no doubt as to its nature. The photograph (Fig. 1) which gives most information about the ice suggests that, at least the part above sea-level (see also Fig. 2) has been formed by the accumulation of layers of snow upon the surface, more quickly than the ice was dissolved by the sea beneath. If this view of the origin of the ice sheet be correct, both its horizontal position and the gentle undulations of its surface are intelligible; and it forms no obstacle to belief in the connection of Graham's Land and Victoria Land along the shortest and most direct line. In this case Ross's ice-sheet will agree in character with the floebergs of Sir George Nares's Palæocrystic Sea, except that they were supposed to have grown by the additions of layers of ice from the sea below, instead of by the fall of snow from above. In this connection, some information as to the rate of solution and growth of the ice in sea-water at various temperatures would have been useful. Captain Scott tells us that such observations were suggested in the "Antarctic Manual." I have been unable to find there the passage referred to. The suggestion is, however, dismissed (vol. i., p. 305) as ridiculous. More than once during the course of the expedition the observations desired were accidentally noticed, but the conditions are not stated with sufficient precision to be of service. The structure of Victoria Land, both geographically and geologically, is much as was expected from the considerations which led to the conclusion, first suggested by Ritter, that the eastern coast of Victoria Land represents the continuation of the volcanic line of New Zealand, and that a plateau occurs behind it. The discovery of the plateau structure seems to have occasioned surprise, though the hope was expressed in NATURE, April 25, 1901, p. 612, that one party would "" cross the volcanic mountain chain to the

plateau that probably lies beyond it.” The geological structure, as described in Mr. Ferrar's interesting chapter, consists of low-lying archæan coast hills, beyond which occur sheets of horizontal sediments and broad sheets of plateau basalts. Huge volcanic cones occur off the main coast line, like the worn down volcanic hills of Dunedin and Bank's Peninsula in New Zealand, and apparently there are great volcanic cones on the plateau near its edge. It would be difficult to find land with a structure more typical of the Pacific coast type.

In contrast to the extensive discoveries achieved by the sledging parties from the winter quarters are the limited results obtained at sea, which make the title of the book, "The Voyage of the Discovery," somewhat of a misnomer. In the book 176 pages are devoted to describing the whole voyage of the Discovery from London to London, and 698 pages to describing the sledging and other work on shore. It was hoped that the Discovery would have thrown some light on the two chief problems offered by the outline of Antarctica, in the area reserved for the British sphere of operations. After the discovery of Coats Land by the Scottish expedition, the longest unknown stretch of the Antarctic coast is that south of the Pacific. It was believed from the work of Ross and Cook that land exists connecting Graham's Land to that on the eastern edge of the barrier. The Discovery has con

firmed the existence of land close by the point where Ross described his " strong appearance of land "; but the necessity for the whole expedition returning to winter on McMurdo Sound prevented the discovery of its nature. Captain Scott seems disposed to regard this land as probably volcanic, and Mr. Ferrar as probably continental.

It was also hoped that the expedition would determine the character of the land to the west of Cape Adare; for a section along that coast, which cuts across the grain of the continent, would no doubt give more information as to its structure, than could be obtained along the coast of Victoria Land or by a traverse of the ice-clad interior. But here again the expedition had to return from the threshold of the unknown regions. This was Captain Scott's misfortune, and was in no way his fault. It was the result of the plan of the expedition being to keep the Discovery at the winter quarters. The limited work done by the Discovery at sea, and its inability to accomplish the much desired deepsea trawling, is possibly due to the heavy demands on the available coal supply made by her engines; for the 500 horse-power which they gave required a large consumption of fuel, and this rendered impossible any prolonged period of full steaming away from a coaling station. Whether the Discovery was a complete success as a ship appears doubtful. Captain Scott praises many features in its design, and of its magnificent strength there can be no question. But in spite (vol. ii. p. 327) of what Captain Scott calls the "depth of sentiment " he naturally feels for the ship, "which for long proved such a comfortable home," he says that when they tested her sailing qualities they "found to our chagrin that they were exceedingly poor "; she had a fine capacity for rolling, sometimes going over 90°, and he describes (vol. ii. p. 375) her "lurching from side to side in the most uncomfortable fashion while our consort [the Terra Nova] followed in our wake with scarcely a movement." Her leakiness is described as a continual source of trouble, and the only expression of irritation in the book is at "another very stupid arrangement" in the ship (vol. i. p. 339). But for the somewhat meagre results achieved by the Discovery Captain Scott is not responsible; if the ship could have been kept at work at sea, while Captain Scott was doing his sledge journeys on land,

a wider and richer harvest of results would doubtless have been obtained. J. W. GREGORY.

KECENT ETHNOLOGICAL PUBLICATIONS FROM THE FIELD COLUMBIAN MUSEUM,'

OF peculiar interest is Dr. Dorsey's account of the

ceremonial organisation of the Cheyenne, which dates back, according to tradition, to two or three thousand years ago, being founded by Motzeyeuff, a prophet who came as a messenger from the Great Medicine with four great medicine arrows, which were sent to the Cheyenne as an emblem for their future, decreed they should produce effects beyond natural as they possessed magic, and the Great Medicine powers. These arrows are still preserved, but two of them are in the hands of the Pawnee. prophet organised five societies-the Red Shield. Hoof-rattle, Coyote, Dog-men, and Inverted Bowstring. The first two of these are concerned with

The