by the chronoscope, convince the authors that the inhibition or facilitation thus experimentally produced is one which cannot be . . . explained neurologically as a division of energy, or drainage." They believe that "an association cannot be explained as a mere path of lowered resistance," but that it "involves other processes which prevent any other stimulus from using the same neuroses at the same time. . . and which block any other association that is tending to operate at the same time, even though both will lead to the same end result." IN vol. viii., Section D, No. 3. of The Philippine Journal of Science, Mr. A. E. W. Salt gives an elaborate account of the endowment provided by Francisco de Carriedo y Peredo, the greatest benefactor of the city of Manila, who died in 1743. From the funds received under his will, a water supply was provided for the city until the American occupation. A new system to supplement the ancient supply was opened in 1908. Water is now brought from an almost virgin watershed of one hundred square miles in area, and thence carried to a storage reservoir with a capacity of 210,000,000 gallons. The city, however, is so rapidly developing that this system is barely adequate to the needs of the population. Mr. Salt has done good service in directing attention to the benevolence of a citizen who, at a time when sanitation occupied little public attention, devoted his wealth. to this excellent purpose. IN Professional Paper No. 79 of the United States Geological Survey, Mr. H. S. Williams discusses the recurrent Tropidoleptus zones of the Upper Devonian in New York. In preparing the data for the Watkins Glen-Catatonk folio (No. 169 Geol. Atlas USUS, Geol. Survey, 1909) the occasional discovery of Tripodolpetus carinatus (Conrad) in strata far above the supposed range of the species or of the fauna with which the species is normally associated led the writer to undertake an examination of the sections and sequence of fauna where they appeared. The result throws important light upon the regional geography. The departure and return of the fauna must have been due to diastrophic changes which produced recurring favourable or unfavourable conditions for the existence of the fauna. Those changes of conditions may have resulted from the alternate closing and reopening of an actual passage-way which obstructed or admitted the access of the fauna and of waters favourable to them, or from changes that affected the direction, character, or volume of the existing ocean currents. THE insect food of Canadian fresh-water fishes forms the subject of an article by Dr. Gordon Hewitt, the Dominion entomologist, published in the fourth annual report of the Commision of [Fish] Conservation of Ottawa. Attention is directed by the author to the futility of attempting to restock depleted rivers, or to introduce new kinds of fish into Canadian rivers, without taking measures to ensure an abundant supply of suitable insect food. In Europe it has been demonstrated that the artificial cultivation of many kinds of insects constituting the chief food of fishes is perfectly practicable; and in many rivers an insect hatchery is almost as necessary and important as a fish-hatchery. Before such insectaria can be introduced with satisfactory results in Canada, a close investigation into the nature of the food of native or introduced fishes is absolutely essential. A RECENT number of the Zeitschrift für wissenschaftliche Zoologie (Bd. cv., Heft 3) is entirely devoted to a memoir on the chemical composition of the hæmolymph of insects and its significance as regards sexual differentiation. According to the author, Herr Kurt Geyer, the hæmolymph in caterpillars and pupa of Lepidoptera is usually green in females and pale yellow or colourless in males. The green pigment is, as Poulton has already shown, slightly altered chlorophyll in solution, derived from the food-plant; it constitutes a protective coloration, and it is improbable that it has any assimilatory function. The yellow colour of the male hæmolymph is due to the yellow constituents of chlorophyll (xanthophyll). The hæmolymph of non-phytophagous insects shows no such colour difference. When the male and female hæmolymph are mixed a heavy precipitate is at once formed, and this reaction can only be distinguished quantitatively from that which takes place between different species. The author concludes that in insects the entire soma is sexually differentiated in male and female. DR. C. H. OSTENFELD'S account of the biology and distribution of the phytoplankton of Danish seas (De Danske Farvandes Plankton i aarene 1898-1901. Phytoplankton og Protozoer. D. Kgl. Danske, Vidensk. Selsk. Skrifter. 7. Raekke, Naturvidensk og Mathem. Afd. ix. 2. 1913) is of more than local interest. The main work is written in the Danish language, but there is a résumé in French, extending to 65 pp., which in itself constitutes one of the best summary accounts which we possess of the present state of our knowledge of the general problems of the biology of plankton organisms. The Danish seas, extending as they do from the Baltic through the deep waters of the Skager Rak to the North Sea, furnish such wide variations in salinity, temperature, and chemical constitution, that they offer exceptional opportunities for studying the effects of physical conditions on the distribution of the plankton, and this aspect of the subject receives a full consideration in the report. A good bibliography will be found on pp. 346-352. FROM the Kommissionen for Havundersögelser in Copenhagen we have received three further reports dealing with the investigations which have been carried out under the direction of Dr. Johs. Schmidt into the life-histories of eels. These are: Danish researches in the Atlantic and Mediterranean on the life-history of the freshwater-eel (Anguilla vulgaris, Turt.), with notes on other species, by Johs. Schmidt (Internat. Revue Hydrobiologie und Hydrographie. 1912); on the identification of murænoid larvæ in their early (preleptocephaline) stages, by Johs. Schmidt | (Meddel. Komm. Havunders. Fiskeri Bd. iv. 2); and the metamorphosis of elvers as influenced by outward conditions-some experiments, by A. Strubberg (Meddel. Komm. Havunders. Fiskeri Bd. iv. 3). In NATURE, vol. lxxxix., pp. 633-636, Dr. Schmidt himself gave a brief account of these researches, and those interested in the subject will no doubt welcome the more detailed reports. In his presidential address to the Quekett Microscopical Club for this year, Prof. Dendy dealt with the subject of "By-products of Evolution," illustrating. his theme by the spicules, more particularly the microscleres of siliceous sponges. After pointing out that these minute spicules exhibit constant specific characters, and have undoubtedly arisen by some process of evolution, since one form leads on to another, just as in the case of any other characters, it is argued that natural selection cannot be directly responsible for their origin, on the ground that the minute differences in the form of the microscleres cannot be of any importance to the sponge in the soft tissues of which they are scattered without order or arrangement. a By the principle of correlation non-adaptive characters of this kind may be linked inseparably with other characters which being adaptive, are directly influenced by natural selection, in such a way that any variation in the one must be accompanied by a corresponding variation in the other. Thus, non-adaptive character may undergo a progressive evolution indirectly controlled by the action of natural selection. The principle of correlation cannot, however, be invoked to explain the specific forms assumed by the microscleres; it can only help to explain why such characters exist at all and why they should undergo progressive evolution. The specific form of the microsclere must be produced by chemical and physical causes involved in, and controlled by, the hereditary constitution of the mother-cell. SIR F. W. MOORE contributes a useful paper on hardy water-lilies to Irish Gardening (vol. viii. May, 1913), including not merely cultural hints and lists of species suitable for ponds of different depths, but also some interesting remarks on the general biology and mode of growth of these plants. For instance, the author lays stress on the importance of the study of roots to the gardener; observation of water-lilies shows that from early April to June new roots are developed rapidly as the new leaves and flower-buds are formed and the rhizome elongates, while the older roots largely die away after having served as collectors of food reserves during previous years and as anchors during the winter. It is also noted that while, as a rule, the flowers close on bright days between three and four o'clock in the afternoon, if after noon the day becomes wet and gloomy the flowers usually remain open until dark. IN continuation of his investigations into "Southern Hemisphere Seasonal Correlations (NATURE, August 7), Mr. R. C. Mossman contributed a fourth article to Symons's Meteorological Magazine for August. He pointed out an interesting instance of the temporary character of many correlations. The example chosen was the comparison of April to September rainfall at Trinidad (West Indies) with that at Azo (Argentine Republic) for the following six months. Dealing with the fifty years, 1862-1911, it was found that from 1862 to 1877 and from 1895 to 1911 there was no relation between the rainfall of the six-monthly periods; but during the seventeen years 1878-94 the curves showing the rainfall departure from normal are the reverse of each other. The author observes that these results are of importance, as they show that the physical processes that produced a given precipitation at Trinidad during the period under discussion were associated during the six months following by an opposite effect in the south temperate zone, some 2850 geographical miles distant. Mr. Mossman also refers to one or two interesting correlations in other regions, especially one between the rainfall of Java and Trinidad. THE Meteorological Office chart of the North Atlantic and Mediterranean for September (first issue) shows that the last report from the scout-ship Scotia was dated August 7 in 54° 45′ N., 49° 30′ W.; no ice in sight. It is pointed out that the full scope and value of the work accomplished cannot be estimated until the reports of the captain and scientific staff have been submitted. The ice notices which may prove to have been of most value are those relating to the comparatively small quantities that have been seen drifting south in the polar current. An important feature this year is the fact that the ice has been held up, for the most part, north of latitude 43°. The special reports above mentioned will, it is thought, no doubt decide whether this was due to abnormal strength of the Gulf Stream, to unusual weakness of the Labrador current, or to both causes. A CIRCULAR headed "Road Dangers has been widely circulated by the editor of The Automotor Journal. It suggests that the dangers both of vehicular and foot-passenger traffic might be greatly minimised if at crossings the traffic of one street were arbitrarily given a right of way and the traffic of the other street which crosses it were made to go dead slow by a sign that must be obeved. The writer of the circular considers that not only would the accidents that occur from collisions of vehicles at crossings be greatly reduced, but the noisy use of the horn would be no longer necessary. It is difficult to see how the suggestion can be carried out without some enactment giving to a street authority a power to make bye-laws controlling the traffic in the less important streets and which can be enforced by the police. It would be easy for the Chief Commissioner, through his advisers in Scotland Yard, to decide which streets are to be of primary and which are to be of secondary importance, but short of keeping a constable on traffic duty at every crossing it is difficult to see how, with his existing powers, he can instruct them to summon drivers disobeying notices informing them that they must give way to traffic in the preferred streets. WE have received a copy of the third edition of Merck's "Reagenzien-Verzeichnis." It is a volume of 446 pages, and all the commoner reagents, tests, hardening and preservative fluids, and the like are given alphabetically under authors' names, some 5000 formulæ being thus detailed, with references to the literature. There is further a valuable list of the substances for which the tests are employed, and a similar one for those used in microscopic work. Finally, there is an index of the preparations employed for the various tests, with authors' names attached; thus we find that "arbutin" was recommended by Reichard EXHIBITION OF THE ROYAL PHOTO- HE Royal Photographic Society's annual exhibi- THE SPECTRA OF THE STARS.—After many years of patient labour by such pioneers as Rutherfurd, Secchi, Huggins, Vogel, Pickering and his co-workers, Lockyer and McClean, the subject of stellar spectra has attracted during the last decade the attention of an ever-increasing number of students in astronomy, astrophysics, physics, and chemistry. This is no doubt thanks in a great measure to the enormous number of spectra classified in connection with the Draper catalogue, but also largely to the simple nomenclature developed by Miss A. J. Cannon, further simplified by the suggestions of Dr. Hertzsprung: Although classification merely has received a great amount of attention of recent years, perhaps partly due to the prominence given to the matter by the Solar Union making it the work of a special committee, yet many important pieces of work have been accomplished beyond. Such are Campbell's and Kapteyn's work on the relations between radial velocities and type of spectrum, the similar work of Lewis Boss on the relation between proper motion and type, the work of Pickering and others on the distribution of stars of particular type of spectrum with reference to the Milky Way, &c. It is perhaps fitting that the importance of the subject should have led to the publication of a summary in the Memoirs of the Society of Italian Spectroscopists, No. 6, from the pen of Signor G. Abetti. It is, however, passing strange that this IN the publication referred to below Mr. Clarence B. Moore gives us another of his very careful dewriter makes no mention of the work of Rutherfurd,scriptions of the systematic excavations he is underHuggins, Lockyer, or McClean, except perhaps that some of them may be referred to in an "&c." Signor profusely illustrated with most excellent photographs taking in the Mississippi valley, and, as usual, it is Abetti does not deal at all adequately with the literaand coloured plates. By these investigations and the ture on the chemical constitution of the stars. He superb way in which he publishes his results, Mr. THE ARCHEOLOGICAL INVESTIGATIONS does state, however, that titanium stars are on a level Moore is laying a sure foundation for future general nearer to the helium stars than are the iron starsa statement for which we know no justification. SEPTEMBER 4, 1913] NATURE isations. The last year's work covered 519 miles of the Red River confluence were with the found in Mississippi. Few these were mainly in the often Louisiana, as flooded level ground, and the artificial mounds were erected for places of residence; since most of the finds are obtained from graves the spoil was not very large, and as many of the mounds are now utilised they could not be satisfactorily investigated. Along the Red River in Arkansas the conditions in the main are different; mounds containing burials, some of them richly endowed with artifacts, are fairly It abundant, and further northward the lavish use of pottery with burials has often been described. seems probable that the Arkansas mound burials were those of people of consequence. The pottery of Arkansas is as a rule tempered with fine gravel or sand, or with small bits of pottery, though kitchen vessels are often shell-tempered. The ware is thin and carefully modelled. There are few unusual shapes, grotesque or life forms were very rarely attempted, though they occur in the region to the north. Many vessels bear a high polish, and nearly all have incised designs filled in with red or white pigment. Circles, often series of concentric circles (probably sun-symbols), form a frequently recurring design. Decoration in polychrome was very exceptional, though common FIG. 1. more to the north. A remarkable feature-indeed, it form, Among have not from at is of Dr. Hrdlička adds a notice on the human remains. AND SOLAR STORMS N the publication referred to below only the first overlooked. Dr. Bosler regards his countryman Marchand (1887) as the first to claim a connection between the occurrence of magnetic storms and the presence of individual sun-spots or faculæ near the sun's central meridian, but he regards Maunder's observations on the recurrence of storms in the solar rotation period as the strongest evidence yet advanced in favour of this view. He seems to be unaware of Broun's early work. He apparently accepts Sabine's deduction of an elevenyear period-corresponding to the solar period-in magnetic disturbances, but while recognising the strength of the evidence adduced-especially that of Maunder-in favour of solar jet theories, he considers Dr. Schuster to have demonstrated the impossibility of swarms of any kind of electrified particles sticking together all the way from the sun to the earth. The view he inclines to is that earth currents are the immediate cause of most, if not all, magnetic disturbances. The evidence he advances in favour of this view is derived from comparisons of records of magnetic storms at Parc St. Maur and Greenwich-especially sudden commencements "-with corthose known as responding records of earth currents. This from an observational point of view is probably the most important part of the thesis, though only partly novel. 44 sun. The author thinks earth currents may be produced the by movements of electrified matter-associated with faculæ on or spots, protuberances, Taking the case of a cable of 0.25 cm.2 section, made of copper of resistivity 1600, enclosing a circle 8000 km. in perimeter, he calculates that the current induced in the cable by a magnetic field of amplitude 10y and at a distance of one metre from the wire produce an period 10 sec., normal to the plane of the circle, would alternating magnetic field of amplitude 1250y. This is adduced as an illustration of how a small field originating in the sun might be amplified on the earth. The idea may be worth considering, but the problem treated seems somewhat too remote from actuality. The magnetician will find a variety of other interesting matter in the thesis. C. CHREE. "Thèses rrésentées à la Faculté des Sciences de Paris pour obtenir le grade de Docteur ès Sciences Mathématiques." By M. J. Bosler. Pp. 96. (Paris: Gauthier-Villars, 1912.) There are, however, all sorts of interesting details in the life-history, and these details often differ considerably in different types. There are differences in the egg-laying habits; differences in the method of development of the embryo; differences in the way the larva gets out of the egg; differences in the way it feeds and in the nature of its food, and so on; and it is these differences which are of importance to each species in enabling it to fit in among other species in the life of the community. Although there are a number of widely separated species of beetles which inhabit the water, there are two groups which are usually referred to as "waterbeetles," and these may be broadly distinguished as the swimming carnivorous group-the Hydradephaga -and the creeping herbivorous group-the Palpicornia, or Hydrophilidæ. The description of this second group is not strictly accurate, as the larvæ are, apparently without exception, carnivorous, and the perfect insects, although capable of subsisting upon a vegetable diet, in at least many cases enjoy animal food; and although they are somewhat differently constructed from the swimming water-beetles, some of them are very fair swimmers. I propose to outline the life-history of a type of the Hydradephaga, and then to compare with it a type of the Palpicornia; and as a type of the former group I will describe a species of Dytiscus, D. lapponicus, the life-history of which I worked out during last summer. The male and female differ in general appearance, the former having smooth wing-cases, the latter having these grooved or fluted. The male has also a pad on each of the front legs, while the female has quite simple front legs. The slide also shows a full-grown larva, and thus gives an idea of the relative sizes of these two stages of the species. This species is extremely local in the British Islands, only having been found in a few localities in Scotland, and in one in north-west Ireland. It inhabits lochs, usually mere lochans, at altitudes of from 800 ft. upward, and there are certain characteristics about its habitat which make it possible generally to tell at a glance whether a particular lochan is or is not likely to hold the species. As a rule the habitat is a bare stony lochan, with very little vegetation; it has no stream flowing into or out of it, and trout and lapponicus are mutually exclusive. There are usually newts and fresh-water shrimps (gammarus), but otherwise there is always a marked scarcity of animal life. Very few other waterbeetles are associated with lapponicus, which usually is abundant where it occurs. The only place I have found the species in great abundance is in a lochan 950 ft. above sea-level on the island of Eigg. Along its eastern side this lochan is strewn with large stones, and under these the beetle is to be found, often as many as four or five under one stone. It occurs in other lochans on Eigg, 1 Discourse delivered at the Royal Institution on Friday, May 9, by F. Ralfour Browne. and has been found also in Rhum, Skye, Mull, and Arran, but otherwise it is only known from Invernessshire. One place in Mull where it used to occur abundantly is a peculiar loch, situated in the top of a hill, about 800 ft. behind Tobermory. The place looks like the crater of a volcano, but I believe is not so described by geologists. The species has apparently quite disappeared from this loch; it is probably slowly disappearing from our islands, being a remnant of the fauna which abounded when our climate was much colder than it is at present. All my specimens came from the one lochan on Eigg, and they were placed in large tubs in my garden in the north of Ireland. The tubs are filled with water, but the bottom is covered by a thick layer of soil, and in the soil a few species of water plants thrive, chiefly the common water-grass, Glyceria aquatica. The tubs are covered with wire-gauze to prevent the beetles escaping. Now the Dytiscus possesses a small apparatus capable of piercing the tissues of the water-plants, and each time this borer makes a hole in the waterplant one egg is deposited. In my tubs the lapponicus chose the water-grass as the receptacle for its eggs. In its native home this grass does not grow, the only water-plants being a common rush, a species of juncus, and the club rush cleocharis, both possessing round stems. Now, the grass possesses a round stem surrounded by leaves, each leaf consisting of a long sheathing base and a free lamina or blade. sheath is keeled, and in every case the mother-beetle The pierced the leaf-sheath, and always in the line of the keel, depositing the egg in the tissues of the sheath, and this shows the peculiar instinct possessed by the mother in the deposition of her eggs and the extreme sensitiveness of the borer or ovipositor. Although I examined very carefully the plants in the tubs, only twice did I find that the ovipositor had passed right through the sheath and dropped the egg between that and the stem. Lapponicus, unlike our other species of Dytiscus has a very definite egg-laying period, commencing in March and ending in June. From two of the British species I have had eggs in October, December, and February, as well as in the summer months. I collected a number of the eggs, dissecting them out of the leaf-sheaths, and placed them on wet cotton wool in tumblers and watched their development. I do not intend to weary you with the details of the development of the embryo, but I wish to point out that the embryo first appears on a part of one side of the mass of yolk-it does not at first occupy the whole length of the egg-and it then extends first backwards and then forwards, and the sides grow up around the yolk until the embryo ultimately encloses it. The nerve-chord does not increase in length with the embryo, and consequently appears to shorten as the embryo extends in the egg. The development of the embryo occupies about three weeks in June, but temperature affects the length of this embryonic period. In the case of another species, an egg laid in April matured in three weeks, while one laid in winter took six weeks to hatch. I Towards the end of the embryonic period the pressure of the embryo in the shell is very great. accidentally punctured an egg with a needle when turning it over, and immediately a portion of the embryo bulged through, just as the inner tube of a pneumatic tyre tends to bulge through a tear in the outer cover. The pressure is also indicated by the changed shape of the egg during the final stages. During the latter part of the egg-period, there are various slight movements of the embryo, but during the last few hours certain very definite movements |