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At the request of Prof. Armstrong, I have summarised already what seems to me the electrical evidence for the dissociation theory, and I will not repeat what appeared in your columns of May 31; but I wish again to express a hope that someone who rejects the theory will put forward an alternative scheme to explain the mechanism of electrolytic conduction. W. C. D. WHETHAM.

Trinity College, Cambridge, July 13.

The Fertilisation of Pieris.

ON May 20, near Chindi, in the State of Sukét, NorthWestern Himalaya, I was able to make notes on the pollination of Pieris ovalifolia by Pieris brassicae, Pieris soracta, and other insects. Pieris ovalifolia, D. Don, at Chindi, grows to be a small tree in forests of Pinus longifolia and Pinus excelsa on hill-sides about 6000

feet, where in May thousands of Pieris soracta, and hundreds of Pieris brassicae, flit through the trees.

My first observations were made about 6 a.m., before

I give here just a few instances of the double use of a generic name. Liparis is the nun moth of Europe and an orchid of Europe; Îris is an insect and the well-known plant; Lælia is a moth and an orchid; Adesmia is a beetle and a shrub; Castalia is a beetle of India and the water-lily, while Castalius is an Indian butterfly; Graeffea is a Phasmid of Fiji and a plant of Fiji; Empusa is an insect and an insect-killing fungus; Prosopis is a bee and a plant, Stilbum is a Chrysid and a fungus; Acrocephalus is a bird and a herb; Taphria is an insect and the legitimised form of Taphrina, a fungus. To emphasise my point it will be my endeavour to ascertain if a fungus of the genus Empusa can destroy the insect Empusa, if Castalius visits Castalia, and if Acrocephalus eats the seed of Acrocephalus I. HENRY BURKILL. Indian Museum, Calcutta.

the sun was fully on the hill-side; and then the Pieris F

flowers were visited by Bombus haemorrhoidalis, Smith, in a very diligent way. Later, after the sun was well up, came Pieris brassicae, Schrank, to the flowers, and then many individuals of Pieris soracta, F. Moore, which is in May a most abundant butterfly. With the butterflies a large steel-blue and orange wasp came to the Pieris bushes, and bit holes in the corollas, which later little Aphids also used for stealing the honey.

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Pieris branches stand horizontal, with the leaves on a plane above the racemes of flowers. There are twenty to thirty flowers on a raceme, and the topmost open as the lowest die. Each flower is a bell, like that of one of our common English Ericas, ΙΟ mm. long, and very slightly constricted at the middle; the mouth is only 2 mm. diameter. Pierids and Bombus suck honey hanging under the bells, except where some fortuitous circumstance brings the flowers of one branch close to the leaves of another; and then the butterflies are very ready to try to get the honey without having to hang back downwards to reach into the bells. When once back downwards they walk as on a causeway along the long, regular racemes, generally from younger to older flowers, i.e. towards the base.

Pieris anthers are two-horned, as are so many of the anthers in the Ericaceæ, and with the help of their filaments make an entanglement at the constriction of the bell. The filaments are much more bent into an S than

is usual in the Ericaceæ, and form a spring which, by pressing with the lower curve of the letter against the corolla, holds the anther pores against the style, in such a firm manner that they can only free the powdery pollen when the pressure of the spring is interfered with. This the visiting insects do, and receive a shower of pollen on their heads or probosces. As it is impossible to slit the corolla without causing pollen to fall, the part it plays in keeping closed the anther pores is evident ; and it is also impossible to push a needle past the ring of anthers without liberating pollen. The stigma is close to the mouth of the flower, and is bound to be touched by an insect's tongue before it touches the anthers. When mature it is 4.5 mm. beyond the anther-ring. The stigma matures after the opening of the flower, and the style grows 1.5 mm. between the opening of the bud and its maturity, but the anther-pores appear in the bud. Hones is secreted very abundantly behind the slightly broadened bases of the filaments. The duration of the flowers is several days. After the fall of the corolla, the sepals close over the ovary, and the pedicel ultimately turns upwards.

I have communicated the above actual observations to NATURE in the hope that both zoologists and botanists may read them, and be reminded of the possible inconveniences resulting from using the same generic name for two even very distinct organisms. I admit that we are not at present at all likely to rule that a previous use of a name in zoology or botany precludes its use in botany or zoology; but it is desirable to do what one can to avoid using used names, and to forward that end indexes like Durand's "Index Generum Phanerogamarum" become the more and more wanted, especially from the zoologists.

AUSTRALIAN ORIGINS.'

F the enthusiasm which leads a man of science to travel at midsummer to one of the hottest regions of the world may be taken as evidence, geology will soon have much to say on Australian anthropological problems. Prof. Gregory, at the instigation of Dr. Howitt, visited the Lake Eyre region, with a prospect of encountering a temperature of some 120° F., in order to throw light on the legends of the aborigines and the problem of their original home. All over Australia are found stories of monsters like the Bunyip; but in the Lake Eyre region they present peculiar features; the animals, called Kadimakara, are said to be extinct, and are represented as arboreal in their habits according to one form of the legend, aquatic in another. The latter is of no special interest, but it is difficult to see how the idea of sky people and animals could have originated in Australia, the vegetation of which is not apt to suggest the idea. Prof. Gregory sees in it evidence of migration, either of legends or of their narrators, from tropical parts.

It is certain that at the present day transmission of the dramatic performances known as corroborees is very common. The expedition saw on the Peak Station, west of Lake Eyre, a corroboree known to have travelled from North-west Central Queensland since the year 1893. From a photograph in the possession of the present writer it is certain that the dance called Molongo in Queensland and Tji-tjingalla near Lake Eyre was known to the Arunta at Alice Springs in 1903 or 1904; but whether it came via the Peak or from the north-east cannot be determined. From Dr. Howitt and others we learn that new songs are passed from tribe to tribe, their meanings being forgotten; and the tendency seems to have existed in the 'thirties of the last century, so that it cannot be put down to European influence and easier communication. There is, however, no similar evidence of transmission of myths; prima facie, therefore, there is no ground for supposing that the Kadimakara story is of foreign origin; to raise the presumption it would be necessary to find its analogue elsewhere.

The argument for the foreign origin of this myth rests in part on the assumption that the geographical conditions of the region have been unchanged since its present, or rather, in only too many cases, late occupiers reached it. In proof of this Prof. Gregory quotes legends explaining the origin of natural features and representing them as the same when they were first known as they are at the present day. But it is clear that we are not entitled to assume the

1 "The Dead Heart of Australia; a Journey round Lake Eyre in the Summer of 1901-2, with some Account of the Lake Eyre Basin and the Flowing Wells of Central Australia." Pp. xvi+384. (London: John Murray, 1906.) Price 16s. net. By Prof. J. W. Gregory, F.R.S

same age for all items in a stock of folk-tales; and in any case the evidence of myths is untrustworthy in matters of history. It seems possible that man was in the area before the great climatic changes described in the work before us; the failure to find worked stones associated with the extinct marsupials cannot be regarded as decisive until a wider search has been made.

Unfortunately, Prof. Gregory was unable to see more than a portion of the Tji-tji-ngalla corroboree. Its transmission raises interesting problems; in Queensland the Molongo is a kind of evil spirit, and it would be interesting to know whether it is in this light that the principal performer is regarded in Central Australia. Some of the words are recorded, and the author is disposed to see in the fact that they are untranslatable by the performers evidence of rapid

that there is no evidence of intermixture, and points to the singular uniformity of type in Australia as evidence of racial purity. Against this it may be said that there is considerable variation in hair, as may be seen by comparing Taplin's South Australian types with Spencer and Gillen's Central tribesmen. As Prof. Gregory points out, the skull is more variable than hair; similarity of physical conditions may have more to do with similarity of skull-type than any original uniformity of physical type.

The latter half of the book is devoted to a discussion of how the dead heart of Australia can be revived, and of the origin of the water supply of the so-called artesian well in Australia. It appears that the scheme for an inland sea, to be formed by supplying Lake Eyre with water from the Southern Ocean, is impracticable. It would cost little less than the amount

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changes in language. But it is the unintelligibility which causes the changes, and not vice versa. song passes from tribe to tribe, and is unintelligible a few miles from its centre of origin. The change in corroboree words is therefore comparable to the variations introduced by children into counting-out rhymes, &c., which they have learnt, parrot fashion, from a foreigner; these changes would not be evidence of modifications in European languages.

By discovering dingo bones in association with those of the Thylacinus, now found alive only in Tasmania, Dr. Gregory has added force to the argument that the dingo was not introduced by man. He also argues that the Tasmanians must have been in Australia before the dingo if, as Dr. Howitt argues, they passed into Tasmania by land. On the relation of the Tasmanians and Australians Prof. Gregory has seen reason to change his view. He now holds

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From "The Dead Heart of Australia.

of our national debt. Prof. Gregory protests against the waste of water from the wells, justifiable only on the supposition that they will never cease to flow. Experience shows that they are already diminishing their supplies, not from any choking of the bores, but from more radical causes, and it is suggested in the work before us that the real source of the supply is not meteoric, but plutonic; in other words, Australia is recklessly drawing on a banking account which has been steadily piled up for tens or hundreds of thousands of years. Unless measures are taken to check youthful extravagance, future generations of colonists will have cause to regret that no heed is paid to the warnings of geologists.

The work is excellently illustrated by numerous maps, plans, and plates. Anthropologists will look forward to the other work on the aborigines which Prof. Gregory promises in the preface. N. W. T.

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Strait and of the drift in the ice contain most new information. The text is illustrated by twenty-nine photographs and plates, many of which are of unusual merit. Most of the photographs were taken by Dr. Cook, others by M. Lecointe, and some by M. Arctowski. M. É. de Wildeman's report on the phanerogams of the Magellan Archipelago is based upon the material collected by M. Racovitza, during a short stay there, before the departure of the expedition to the south. The report begins with a description of M. Racovitza's collection, and, as many of the species were imperfectly known, the author has taken this opportunity of giving a detailed account of them, illustrated by a series of fine plates. Then follows a systematic enumer ation of the phanerogamic flora of the southern part of Patagonia and of the adjacent archipelago, and a detailed table of distribution. The author concludes that the new collections show that the flora of Tierra del Fuego is less primitive and distinct from that of the mainland of South America than had been thought. All the species are found on the American continent, and some of them have a wide distribution. Amongst other British species there are Rumex maritimus, on Tierra del Fuego, while Urtica dioica and Veronica

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FIG. 1.-The stream falling into Torrent Bay, Beagle Channel.-Magellan Strait.

make deep-sea collections within the Antarctic circle. The scientific results of the expedition are in process of publication in a fine series of volumes which will long be an indispensable work of reference on Antarctic geography and biology. The three memoirs the titles of which are given below contain further instalments of the geographical, botanical, and zoological contributions.

66

The second part of the first volume of the 'Rapports scientifiques" of the expedition gives the technical geographical observations, and some account of the methods. Every effort has been made to remove uncertainty as to the geographical positions attained, as the calculations for some of them are repeated at length. The text is mainly devoted to detailed descriptions of the harbours and coasts visited in the Magellan Archipelago, and in the subsequent journey past Graham's Land and through Gerlache Strait, and there is a full account of the long drift of the Belgica in the ice, from February 19,

1898, to March 15, 1899. The volume is accompanied by an atlas of seven charts, of which those of Gerlache 1 "Expédition Antarctique Belge. Résultats du Voyage du S.Y. Belgica en 1897-99 sous le Commandement de A. de Gerlache de Gomery' Rapports scientifiques. Travaux hydrographiques et Instructions nautiques. Vol. i., part i. By G. Lecointe. Pp. 110, xxix plates, with a portfolio of 7 charts. (Antwerp, 1905.)

"Botanique-Les Phanérogames des Terres Magellaniques." By É. de Wildeman. Pp. 222, xxiii plates. (Antwerp, 1905.) "Zoologie-Poissons." By L. Dollo. Pp. 239, xii plates.

1905.)

(Antwerp,

arvensis occur on the mainland. The memoir by M. Dollo on the fish collected by the Belgica discusses problems of more general interest

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FIG. 2.-Sierra Du Fief (Wiencke Island).

than those of the two other reports. It includes a systematic description of the fish collected by the expedition, including three new genera-Cryodraco, Gerlachia, and Racovitzaia. The Cryodraco is of some historic interest, as a specimen no doubt belonging to this genus was caught frozen against the bow of the Erebus during Ross's expedition. The fish was sketched at the time by Robertson, but it was devoured by the ship's cat before it could

be preserved. The fishes collected by the Belgica in the Weddell Sea were all pelagic. One species, a Nematonurus, came from a depth of 2800 metres. In addition to the account of the first deep-sea fish collected within the Antarctic circle, there is an account of a larger collection made in the Magellan Archipelago, accompanied by a bibliography and full account of the fish fauna of that area. The fish are not only described and illustrated with M. Dollo's usual skill and care, but their significance is discussed in the very interesting chapters devoted to their zoo

FIG. 3.-Cryodraco, according to Robertson's sketch made on the Erebus. logical and geographical relations. M. Dollo maintains that the Antarctic fish are of modern development and highly specialised, and are not, as has been thought, a primitive fauna. He discusses the problem of bipolarity, which has commanded wide attention owing to its advocacy by Sir John Murray. M. Dollo maintains that the evidence of the fish gives no support to this theory. Thus he points out that in the Antarctic area the predominant family of fish is that of the Nototheniida, whereas in the Arctic Ocean the dominant group is the Cottida. In the wide distribution of the Nototheniidae in the Southern Ocean and the South Pacific M. Dollo sees further support

of the existence of the assumed Miocene Antarctic continent, connected with New Zealand, Australia,

FIG. 4.-Cryodraco, according to Dollo.

and South America, but separated from South Africa; for eleven-twelfths of the Nototheniidæ are littoral species, and, according to Dollo, they can only have spread along the former shores of this sunken land. J. W. G.

YELLOW JACK.1

TH HE main facts established regarding yellow fever and mosquitoes can be summed up in a few propositions.

(i) The cause of yellow fever is unknown.

1 Report to the Government of British Honduras upon the Outbreak of Yellow Fever in that Colony in 1905. together with an Account of the Distribution of the Stegomyia fas iata in Belize, and the Measures necessary to stamp out or prevent the Recurrence of Yellow Fever. By Rubert Boyce, M.B., F.R.S. Pp. ix+104+13 Plates. (London: Waterlow and Sons Ltd., 1906.)

(2) Yellow fever is transmitted by one particular mosquito, known to science as Stegomyia fasciata, and by no other mosquito or in any other way.

(3) In order to transmit the infection, the Stegomyia must have sucked the blood of a patient during the first three days of the fever, not earlier (during the incubation period), and not later.

(4) The infection is transmitted after an incubation period in the mosquito of not less than twelve days, and the mosquito may still be infectious fifty-seven days after its first infection.

It is a peculiar fact that although there are many species of Stegomyia, so far as is known it is only S. fasciata that is capable of transmitting the disease. If we may accept this as established, it points to a peculiar relationship between the mosquito and yellow fever which is not exactly paralleled by the case of any other disease-transmitting agent, be it mosquito, fly, or tick.

This

In the case of malaria, filariasis, and trypanosomiasis there is not this absolutely limited correlation between the disease and the agent that transmits. Malaria we know is transmitted only by mosquitoes of the subfamily Anophelina of the Culicidæ. subfamily is divided into a number of genera, and not only do different species of the same genus, e.g. Myzomyia culicifacies and Myzomyia funesta, transmit malaria, but also species pertaining to different genera, e.g. Pyretophorus costalis and Anopheles maculipennis, or, if we do not accept these as different genera, and classify them all as belonging to a single genus, Anopheles, still we have the fact of transmission by different species. In filariasis the correlation between Filaria and the mosquito is still less definite; thus not only various species of Culex, but various species of Anopheles all permit of the development of the microfilaria (filarial embryos) in their tissues. (It may be well to say in passing that the proof that mosquitoes actually do transmit Filaria is still wanting.)

Our knowledge of the correlation of trypanosomes and flies, especially species of Glossina, Tabanus, and Stomoxys, is still incomplete. Ngana, the tsetse-fly disease of Africa, is transmitted by species of Glossina,

but not by Stomoxys or Tabanus. The trypanosome of sleeping sickness is transmitted by Gl. palpalis mainly, but also by other species; but it is not yet known which exactly these are.

Again, in the transmission of various species of Piroplasma by ticks, various genera and species of ticks suffice to transmit the same species of Piroplasma.

As to the transmission of Spirochetes by ticks, our knowledge is at present incomplete, and it would be especially interesting to discover if the relationship were as strict as it appears to be in yellow fever, for Spirochetes (invisible) have been suggested by Schaudinn as the possible cause of yellow fever.

The fact, then, that yellow fever appears to be transmitted by only one genus of mosquitoes, and only one species in that genus, points to some very peculiar relationship, and would suggest an organism as the cause, of a different kind from any of those we have mentioned, and, indeed, this is no doubt the case, as, if it had not been so, the cause would have been already discovered.

Yellow fever, then, is transmitted by a particular and practically world-wide mosquito, Stegomyia fasciata. The fact still requires emphasis that mosquitoes only transmit disease from the sick person to the healthy after certain changes have proceeded in the tissues of the mosquitoes, and that mosquitoes

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FIG. 1.- Operations in yellow fever prophylaxis at New Orleans. An outhouse completely closed with paper.

a "conscientious belief" that malaria is due to marshes and yellow fever to digging the soil.

The Stegomyia fasciata is essentially a domestic mosquito, i.e. it frequents houses, it breeds in domestic utensils, pots, cisterns, tubs, tins, calabashes, boats, flower-pots, &c., in fact, in any collection of water about a house.

The destruction of larvæ is, therefore, a comparatively simple matter, and if the water were emptied out, thousands of potential mosquitoes would be at once destroyed. Where it is impossible to empty any collection of water, then the simple device of covering the receptacle with suitable gauze has the same effect. So that the destruction of larvæ of Stegomyia can readily be effected if only people will or can be compelled to do it!

We may express some doubt, however, as to what would happen supposing Stegomyia suddenly by some governor's edict found all their breeding tubs emptied of water or covered over. Would they be content to die, or would they now breed in ditches, canals, slowly-flowing streams, &c., as Anophelinæ do? We think they

town it is conceivable that the condition of things might be no better than before. For the doing away with canals, &c., implies drainage and re-levelling, and is a far more expensive matter than mosquitodestroying in back-yards. But no considerations of this kind should restrain us from doing our utmost absolutely to free a town of its tub-bred larvæ, and that this is possible is shown by experience at Havana and New Orleans.

Not only must the larvæ be proceeded against, but also all adult mosquitoes, and that this is not the impossible task it might at first sight appear has also been shown by the Americans.

By very simple means, by pasting up a house with sheets of paper, and by the use of a suitable fumigating mixture (camphor and carbolic acid), not only rooms, but outhouses and sheds can be expeditiously and completely freed from mosquitoes.

By these means the epidemic of yellow fever in New Orleans of 1905 was rapidly, brought to an end. The history of the epidemic shows what can be done by systematised effort supported by the intelligent cooperation of the whole of a city.

The present very able and comprehensive report sets out at length the conditions prevailing in British Honduras, showing how in Belize, the capital, and other towns all those conditions exist which in the light of our present knowledge should not exist. Stegomyia fasciata exists in profusion, and breeds freely, and so far without hindrance, in water vats, tanks, wells, barrels, tins, and a multitude of other receptacles.

In considering the origin of the outbreak of the disease in British Honduras, the author adopts the view that the disease was imported, and does not discuss another possibility. It is well known, however, that among the native population in yellowfever areas the children suffer from extremely mild attacks of fever, and, indeed, many of these cases are not recognised as such. By this means an endemic supply of yellow fever may always exist, and it may be only at some years' interval that the disease breaks out again in epidemic form.

Apart from this, however, the outbreak of the epidemic is minutely traced, and the difficulty of

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FIG. 2.-House in Belize with waterlogged yard. Numerous water receptacles consisting of barrels

would choose the latter course, and this point is not solely of academical interest, for the most vigorous campaign against tubs and cisterns might have been carried out, and yet the Stegomyia might now be enforced to breed in drains, canals, &c., and if these existed in the midst of the

and kerosene tins.

detection of early cases, and the resulting fatality under such conditions, emphasised.

The necessity for efficient sanitary survey, especially in the matter of breeding-places, is pointed out.

Finally, we have a complete account of the influence on shipping and disturbance of trade of such an out

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