Electricity. Rotatory effect of terrestrial magnetism. - In 1878 H. Becquerel showed that the rotatory influence of terrestrial magnetism on light traversing gases could be accurately measured. The fundamental experiment consists in arranging upon the same horizontal support, movable about a vertical axis, a source of light, a polarizer, a column of the substance to be investigated, and an analyzer mounted upon a divided circle. The axis of the column and of the beam of light is placed in the magnetic meridian, and the plane of polarization noted: the apparatus is then turned end for end; the plane of polarization is still the same, but the divided circle has been turned about, so that the apparent rotation is reversed. The effect was multiplied by successive reflection from mirrors at the end of the column of gas, and also by interposing a thin crystalline plate, which rotated the plane of polarization symmetrically about the axis of the crystal. J. T. The author found that the plane of polarization of the luminous rays, D, is rotated through .9435' in traversing 1 metre of CS2 at 0° C. under the influence of terrestrial magnetism, and that between two points 1 cm. distant, in a magnetic field of strength unity (c. G. s.), the rotation of the same rays in passing through CS2 at 0° C. is .0463.0004. Thus he claims he can measure, by an optical determination, the intensity of any magnetic field whatever to of its value. (Ann. chim. phys., Nov., 1882.) [420 Electric discharge in rarefied air. - Edlund continues his investigation of this subject. He connects the combs of a Holtz machine by means of a wire interrupted by a short air-space. The circuit contains in multiple arc a sensitive galvanometer, and a rarefied-air space, 5 mm. long, between aluminium electrodes. The galvanometer is also shunted by a wire; and one junction of this shunt with the rest of the circuit is grounded. When the Holtz machine is worked, frequent sparks pass, and the galvanometerneedle finally attains a nearly constant deflection. The singular fact is observed, that this deflection is many times greater, when the galvanometer is shunted by the rarefied-air space, than when it is not so shunted. The explanation proposed is, that, after each spark from the Holtz machine passes through the rarefied-air space, a 'disjunction,' or reverse current, is set up by the e. m. f., which the discharge has generated at the surface of the electrodes. This current passes through the galvanometer in the same direction as the current from the machine. Edlund's articles seem to be of value in calling particular attention to the long-recognized resistance at the surface of the electrodes in a discharge-tube, thus making it appear probable that the proper resistance of rarefied air has been overestimated, and so tending to remove the difficulty at present felt in regard to the height of auroras. Edlund's own conclusion -viz., that empty space, or rather the ether, is an excellent conductor will probably be accepted by few. -(Phil. mag., Jan.) E. H. H. ENGINEERING. [421 The Corinth canal.- As early as the year 625 B.C.. the idea of connecting the gulfs of Corinth and Aegina by means of a canal was conceived. It was abandoned after some discussion, from the belief that the level of the sea in the gulf of Corinth was higher than that in the gulf of Athens. Later, Julius Caesar, Caligula, and Nero employed engineers to plan this work; but little was actually accomplished. Quite recently Gen. Türr obtained a concession from the Hellenic government to cut a canal across the isthmus, of dimensions sufficient to pass one vessel at a time; the cross-section being the same as that of the Suez Canal, i.e., 72 feet wide at the bottom, and with a depth of 26 feet. Three several routes were surveyed, being respectively 3.94 miles, 4.2 miles, and 6.8 miles in length. The first of these lines was selected, being the same as that proposed by Nero's engineers. The work was commenced last May, the estimated cost being thirty million francs. It is believed that the investment will be a good one, as the traffic across the isthmus is now from five to six million tons annually. - (Engineering, Dec. 8, 1882.) [422 G. L. V. The Kinzua viaduct.—This remarkable structure carries a branch of the New-York, Lake-Erie, and Western railroad, over a deep gorge in western Pennsylvania, the Kinzua Creek. This is the highest railroad-bridge in the world, the distance of the rails above the stream being 301 feet, while the whole length of the work is 2,052 feet. The structure is designed to sustain a continuous line of the heaviest locomotive engines from one end to the other, or 2,660 tons in all. The original conception of a viaduct at this place is due to Mr. O. W. Barnes, C. E. The execution has been made under the general direction of Mr. O. Chanute; the details being arranged and the construction carried out by Messrs. Clarke, Reeves, and Co. of Philadelphia. The total cost of this enormous structure was but $237,000, and the time occupied in building was only 94 days. The towers were erected without scaffolding of any kind, while the superstructure was placed in position by means of a travelling crane; a method which secured economy of both time and money. Especial care has been taken to enable the structure to resist the severest gales of wind. Ample provision, too, has been made for the effect of heat and cold upon the iron-work. — (Engineering, Dec. 22, 29, 1882.) G. L. V. [423 Centrifugal pumps.-The common objection to this kind of pump is, that it wastes a large percentage of the power applied; but G. Kapp of London maintains, that, if the pump is rightly made and rightly worked, it will utilize as large a percentage of the applied work as any hydraulic machine. He gives the mathematical theory of the centrifugal pump, shows how to find the loss through friction, investigates the best form for the wheel-blades, and lays down general rules for the construction throughout. -(Civilingenieur, heft 4, 1882.) G. A. H. CHEMISTRY. [424 (General, physical, and inorganic.) Formation of natural manganese binoxide, and certain reactions of other peroxides. — From the results of M. Berthelot, it seems that the heat of formation of Mn O, in the reaction Mn O +0 = Mn O, is larger by 3.9 cal. than that of Mn CO3 in the reaction CO (in solution) + Mn O= Mn CO3. An explanation is thus found for the formation of the mineral pyrolusite by the action of air, either free, or dissolved in water. In the reactions 2 Fe 0+0= Fe2O3, 13.3 cal. for Fe 0; 3 Fe 0 + 0 = Fe3O1, + 10.3 cal. for Fe O; CO2 (in solution) + Fe O=Fe CO3, +5 cal. (or, CO2 (gaseous), +7.8 cal.), more heat is evolved in the formation of the oxide than of the carbonate. The stability of Ba CO3 is shown in the reactions Ba + 0 = Ba 0, + 6 cal.; Ba O + CO2 Ba CO, 28 cal. Hydrogen peroxide cannot be formed from Mn O2, since there would be an absorption of heat: Mn O2 + HCl = Mn Cl2 + H2O2, −9.7 cal. It cannot be formed from ferric oxide, since the quantity of heat absorbed would equal - 16 cal. With barium peroxide, heat is evolved: Ba O2+ 2HCl = Ba Cl2 + H2O2, +11 cal. — (Comptes rendus, xcvi. 88.) C. F. M. [425 Electric conductivity of silver chloride, bromide, and iodide.-W. Kohlrausch finds that silver salts of the halogens offer less resistance to an electric current than sulphuric acid. In the order of their conducting-power, the chloride stands first, the iodide last, and the bromide occupies an intermediary position. (Ann. chim. phys., xxvii. 612.) c. F. M. [426 C. F. M. Antiseptic character of carbonic-dioxide gas. -In an atmosphere of this gas, H. Kolbe finds that the quality of fresh beef can be preserved for several weeks, even in a warm room. Fish, game, mutton, and veal begin to decay after a few days. - (Journ. Prakt. chem., n.f. xlvi. 249.) [427 Investigations on uranium. - For the atomic weight of uranium, the values 120, 180, and 240 have been proposed, the latter appearing in Mendelejeff's classification. In order to decide which of these values is correct, C. Zimmermann determined the vapor density of the tetrabromide and tetrachloride, and the specific gravity and specific heat of the metal. Vapor density of the tetrabromide obtained, 19.46; calculated for UBr, (U240), 19.36: of the tetrachloride obtained, 13.3; calculated for UC14 (U = 240), 13.21. The metal was prepared by ignition of a mixture of the chloride with sodium covered with salt. Specific gravity, 18.7; atomic volume, 12.84; specific heat of the melted metal, 0.02765. This value multiplied by the atomic weight (240) gives, as the atomic heat, 6.64; the law of Dulong and Petit requiring 6.64. Uranium must therefore occupy a position in the sixth group of the periodic system with chromium, molybdenum, and tungsten. (Ann. der chem., 216, 1.) C. F. M. [428 Heat of formation of volatile organic bodies. The heat of formation of such compounds as carbon tetrachloride, chloroform, and perchlorethylen has not been determined, on account of the great difficulty of obtaining complete combustion. In the combustion of compounds of chlorine and carbon containing a small percentage of hydrogen, Julius Thomsen obtains accurate results by burning the volatile substance, mixed with hydrogen, in a special form of apparatus, which he has devised for this purpose. Thomsen concludes from his results, that carbon possesses an equally strong affinity for hydrogen and chlorine. The heat of formation of ethylen and perchlorethylen are nearly the same; and, assuming 14,130 cal. as the most probable value of the double bond between the carbon atoms, the affinity of a hydrogen atom for carbon would be 15,080 cal., and that of a chlorine atom, 14,330 cal. (Berichte deutsch. chem. gesellsch., xv. 2996.) C. F. M. [429 Constitution of carbonic acid.-Since a solution of carbonic dioxide in water dissolves magnesium with evolution of hydrogen, M. Ballo concludes that it contains the hydrated acid H2CO3. As a further proof, he mentions the fact that potassium and sodium bicarbonates dissolve magnesium, forming the carbonate MgCO3. 3 H2O. The formation of magnesium sulphite, by the action of SO2 in solution upon the metal, indicates the hydrated acid H2SO3. (Berichte deutsch. chem. gesellsch., xv. 3003.) C. F. M. MINERALOGY. [430 Cryolite. A review of the history of the fluorine minerals, especially those occurring with cryolite from Greenland, is given by P. Groth along with results of renewed crystallographic and chemical investigation. Crystals of cryolite, after having been identified and measured, were given over for chemical analysis to J. Brandl, whose results agreed very closely with the composition expressed by the formula 3 Na F, AlF3. The results of the renewed crystallographic measurements prove the mineral to be monoclinic with the axial relation a:b: c = 0.9662 : 1 : 1.3882. B = 89° 49. The optical deportment of the mineral also indicates its monoclinic character. — (Zeitschr. kryst., vii. 375.) s. L. P. [432 W. M. D. PHYSICAL GEOGRAPHY. - Commander 1433 Former great tides. Prof. R. S. Ball, in a second lecture on this question, reviews the criticisms of his previous statements, and repeats his belief that the accumulation of the oldest stratified rocks was very probably aided by this newly discovered and very important agent; namely, the stronger tides produced by the moon when not so far from the earth as it now is. - (Nature, Dec. 28, 1882.) [434 Gulf-Stream. Bartlett's recent measures on the coast-survey steamer Blake show that the current off Florida, where the channel is 48 miles wide, and the deepest point 439 fathoms, has a cross-section of 429,526,240 feet; a velocity from one to five, averaging three miles an hour; a discharge of 51,000,000,000,000 gallons an hour; and a temperature varying from 78° to 83° at the surface, and from 57° to 44° at the bottom. Farther along our coast, the current flows over an even plateau, narrowing toward Cape Hatteras, about 400 fathoms deep, and suddenly dropping off to over 2,000 fathoms at its eastern edge. In the stronger parts of the stream, the bottom is swept clean, and consists of firm coral rock, hard enough to dent the brass cylinder of the sounding-apparatus. Where fine deposits occur, south of Charleston, they are of pteropod ooze, characteristic of the Caribbean and Gulf of Mexico; farther north, globigerina ooze becomes more common, as it is in the open north Atlantic. The division between these two deposits is considered the boundary of the cold, arctic current which follows down our shore from the north, passing under the Gulf-Stream off Hatteras, where the shallow plateau forces it out. No warm and cold bands or bifurcations were found in the surface-waters till off Hatteras, and no distinct cold wall.' Near shore the current was much influenced by winds. A brief description is given of the Siemens deep-sea thermometer, based on the variation of electrical resistance in metals with change of temperature. Measures made with this and with the Miller-Casella thermometer show almost absolute agreement, even at considerable depths. (Bull. Amer, geogr. soc., 1882, 69. Further account of Bartlett's work may be found in Proc. U. S. naval inst., vii. 1881, 25; viii. 1882, 221.) [435 W. M. D. GEOGRAPHY. (Europe.) French census of 1881.-After deducting the number of foreigners temporarily resident in France, estimated at about 1,000,000, Chervin finds that the population increased with extreme slowness, or even remained stationary, when compared with the enumerations of 1872 and 1876. Departments showing an increase have grown by immigration. Decrease of population is found even in some of the rich and well situated departments, as parts of Normandy; and the same districts show a large percentage (40 or 50) of rejections from the conscripts for recruiting the army. Both these marks of a lack of healthy growth are ascribed to the effects of drunkenness, which is unfortunately prevalent in some of the communes of this region. - (Comptes rendus soc. géogr. Paris, 1883, 40.) W. M. D. [436 Geographic work in Spain. -According to a summary by Ferreiro, the geographical and statistical institute of Spain have the past year determined the force of gravity at Madrid, and the latitude and longitude (telegraphic) of Madrid and Bajadoz. The difference of level between the Atlantic and Mediterranean is found to be +0.6625 metre: for more accurate determination of this in the future, automatic temperature, pressure, and wind registers have been established at Alicante, Santander, and Cadiz. — (Bol. soc. geog. Madrid, xiii., 1882, 317.) (Atlantic Ocean.) W. M. D. 1437 Cape Verde Islands. This seldom - visited group was examined by Dr. C. Doelter of Graz in the autumn of 1880. The islands do not consist exclusively of volcanic rocks, but contain also gneiss, mica and clay slates, and limestones, lending support to the view that they make part of a continental mass once of considerable extent. Their former direct connection with the mainland is, however, questionable, as the opposite shore of Africa does not contain similar formations in their latitude. (A connection would seem more probable north-eastward to the Atlas range.) Doelter's geological results are given in Die vulkane der Kapverden und ihre producte (Graz, 1882). This is to be followed by a general narrative including his journey to western Africa, with the title Nach den Kapverden und dem Rio Grande (Leipzig, Frohberg). (Peterm. mitth., 1883, 72.) w. M. D. [438 Atlantic Soundings. - The brothers Siemens have established a broad reputation by their technical as well as scientific work, ranging from their copper-works in the Caucasus to the construction of cables and telegraph-lines through oceans and wildernesses, as well as to practical researches in electricity. It has not, however, been generally known, that, since 1874, they have undertaken deep soundings in the North Atlantic from one of their own vessels, in connection with their work of cablelaying. Their results have lately been published (Stanford, London) in three charts, giving a valuable addition to our knowledge of the relief of the seafloor in the cable-zone between Ireland and Newfoundland. The soundings were made with Sir William Thomson's steel wire apparatus, and, by repeated measures in the same place, are found accurate within a few fathoms, even in depths of two miles. The charts are of limited areas; one including the Faraday Hills,' N. lat. 49° 20′ to 50o, W. long. 28° 30′ to 30° 15'; the other two, in the region of the Vlamic cape, east of the Newfoundland banks. ―(Peterm. mitth., 1883, 39.) W. M. D. [439 The 'Travailleur's' cruise in 1882. — Lieutenant Parfait reports that the Travailleur spent July and August of last summer in following near the coast of Spain and Morocco as far as the Canaries, and The back by Madeira to Lisbon and Rochefort. weather was much worse than was expected; but 71 dredgings were made in depths from 50 to 1,800 fathoms. The 100-fathom plateau was found along the northern coast of Spain, with a width of about twenty miles; beyond its border the depths were very variable, as had been the case in the previous cruises. With this rapid change of depth, the character of the bottom changed also, and the fauna was local. Off Morocco, the bottom was more even, and was covered with a soft reddish mud; the fauna was new and interesting. Among the Canary islands the depths were variable; the bottom was almost barren of life, and was strewn with volcanic dust and ashes. By Madeira, the dredge was often brought up torn by the corals on the bottom.. (Comptes rendus, soc. géogr. Paris, 1883, 55, map.) [An account of the outfit and previous soundings of the Travailleur is given by Milne-Edwards (Bull. soc. géogr., 1882, 93.)] W. M. D. BOTANY. Cryptogams. [440 Marine algae of Germany and Austria. The first three parts of the second volume of Rabenhorst's Kryptogamen-flora contain an account of the marine algae of Germany and Austria by Hauck, illustrated with numerous and excellent woodcuts, showing the structure of the fronds and fruit of the different genera, and three full-page photolithographs of species of Corallineae. The parts already published include the lower orders of Florideae, from Porphyraceae to Cryptonemiaceae. The descriptions are clear and full, and the synonymy carefully arranged; and the work will be of great value to American algologists, as it gives the best comprehensive account of the European genera of red seaweeds, the greater part of which have representatives on our own coast. -W. G. F. [441 Reproduction in Saprolegniaceae. — The Botanische zeitung contains a reply of DeBary to the remarks of Pringsheim in the Berlin Monatsbericht, in which he questioned the accuracy of some of DeBary's statements in his work, Beitraege zur morphologie der pilze, heft 4. DeBary regarded those forms in which ripe spores were produced in oogonia without the intervention of pollinodia (which, in most of the species, make their way into the oogonia) as instances of apogamy, and considered that the forms in question were originally derived from some form having proper pollinodia, but had gradually lost their sexuality. Even in the species of Achlya in which pollinodia are present, DeBary failed to see any direct communication between the contents of the oogonia and pollinodia. Pringsheim, on the other hand, describes bodies which he calls spermamoebae, which are contractile masses of protoplasm formed in the pollinodia, and which may be discharged through the walls of the pollinodia without any apparent opening, and unite at once with the oospheres when the pollinodia are in the oogonium, or, in case they do not reach the oogonia, as in some species of Achlya, the spermamoebae are discharged into the water, and then make their way into the oogonia. In the Botanisches centralblatt, Zopf maintains that Pringsheim's spermamoebae are amoeboid parasites. DeBary believes, that, even on the supposition that the spermamoebae are not parasites, there are species of Achlya and Saprolegnia in which sexuality is entirely wanting, and that one cannot assume, as Pringsheim has done, that, in the forms in which the oospores are produced without any apparent formation of pol Leafy berries in Mitchella repens. - Monstrous fruits of partridge-berry, from the valley of Cayuga lake, have been studied with attention by Prof. Dudley, who gives several good figures of the malformations. The following statement shows that the cases possess more than ordinary interest: "The true peduncle has entirely disappeared; and those parts of the petioles coming in direct contact with the berry have become part of it, and have readily assumed its color, texture, and general aspect. But this union has not interfered with the fruitfulness or development of the ovary; the seeds being present, and the size of the berry not being under the average.' -(Torrey bot. bull., Jan., 1883.) G. L. G. [443 Fertilization of Asclepias cornuti.—The structure and development of the asclepiad flower have been restudied by Mr. T. H. Corry, who stated the result of his work before the Linnean society Dec. 21, 1882. Self-fertilization, with the parts in situ, is believed to be impossible. —(Nature, Jan. 11, 1883.) W. T. [444 Pollination of Arum italicum. - Dr. Kraus, who has recently studied at Rome the rise of temperature observable in the spathe of this aroid, finds that the maximum is reached between four and six P.M.,when it may exceed the temperature of the surrounding air by 27.7° C. At this time the stigmas of the pistillate flowers are receptive, and the spathe opens to allow the entrance of small diptera, which are attracted by the warmth and shelter offered. If they have previously escaped from older spathes, they bring pollen to fertilize the mature pistils. Their escape is prevented by a whorl of rudimentary stamens, as in A. maculatum and some spathes of Arisaema triphyllum. The temperature gradually falls until morning, when each stigma, having wilted, emits a drop of nectar that is greedily eaten by the flies. The stamens now dehisce, and the insects, pollen-laden, escape to visit other young spathes later in the day. (Abhandl. naturf. gesellsch. Halle, xvi.; fide Kosmos, Dec. 30.) [446 W. T. ZOOLOGY. Polyps. Operculate corals.— G. Lindström has just issued an important memoir on the operculiferous corals of the paleozoic formations, illustrated with nine fine plates. He divides them into two groups, — Calceolidae and Araeopomatidae; the former containing Calceola, Rhizophyllum, and the recently described Platyphyllum Lindström (upper Silurian of China), -all with opercula of a single valve, and Goniophyllum, with an opercular apparatus of four pieces. None of the species are new; though Platyphyllum sinense has barely entered into paleontological literature in the fourth volume of Richthofen's China.' The second family contains the new genera Areopoma and Rhytidophyllum; the former proposed for Cystiphyllum prismaticum Lindström (1868), from the Silurian of Gotland, and the latter for R. pusillum, a new species from the same formation. A broken operculum from Lerberget, not named, is believed by the author to represent a new genus of the same family. Remarks follow on Pholidophyllum and Syringophyllum. Chelodes Dav. & King, a very problematical genus, is referred to as probably Chitonoid. The text (ninety-four pages) is in Swedish. Twenty-one species are illustrated. (Svensk. vet. akad. handl., vii. iv., 1882.) W. H. D. [447 Mollusks. European land-shells. The first supplement to the second edition of Kobelt's catalogue of the European land and fresh-water mollusk-fauna is just published. It is presented in the shape of a systematic catalogue of species, with synonymes, locality of publication, and habitat, for each of the additions, which are very considerable. Most of the real additions are from the Caucasian region, the borders of the western Mediterranean, Italy, and Sardinia, and are due to Boettger, Kobelt, Paulucci, Lessona, and Pollonera. To Locard and Bourguignat we are indebted for an extraordinary number of new names, applied to variations and varieties of well-known species. The amount and character of the current literature of this topic may be imagined from the fact that this supplement contains about twenty pages of new names supposed to be valid, and five pages of pure synonymes. In the same issue appears an article by H. Tschapeck, on the varieties of Clausilia dubia found in Steiermark. (Nachr. blatt. malac. ges., 1883.) [448 W. H. D. Shells from the Colorado region.— Mr. Stearns has recently received from Indio, Colorado desert, a most interesting lot of Physae, collected by Prof. George Davidson. They intergrade perfectly with one another, connecting P. humerosa with P. heterostropha, and these with P. virgata, etc. Recent data also carry the distribution of Anodonta californiensis two hundred and fifty miles east of the main stream of the Colorado river.-W. H. D. [449 Variations of Pompholyx.-A calcareous deposit occurs in Pyramid lake, Nevada, consisting chiefly of incrusted pine-needles and shells of Pompholyx effusa. These last vary widely from the original type, showing all grades of costation from perfectly smooth to strongly costate, as in Vorticifex; these being the form named costata by Hemphill. Others show decided inclination to become umbilicated, thus verging toward Carinifex and its allies.-W. H. D. [450 haemaglobin. Lankester's second specimen had only one genital papilla and orifice, instead of two, and contained five males, which live, as in Bonellia, as minute parasites on the female. The male is provided with a pair of large genital setae, although such are wanting in the female. — (Ann. mag. nat. hist., xi. 37.) c. s. M. [452 Myriapods and arachnids. The blastopore and mesoblast of Peripatus. -The late Prof. Balfour was engaged, just before his death, upon a monograph on the anatomy and development of Peripatus, and left a series of notes, completed manuscripts, and drawings, which it is intended to publish in the Quarterly journal of microscopical science for April next. Some of the results have been presented as a preliminary note to the Royal society of London. The results are briefly as follows: that a widelyopen slit-like blastopore is formed in the early oval embryo. The blastopore, which occupies the median ventral line, becomes closed in its centre, an anterior portion remaining open as a mouth, while a posterior portion apparently becomes the anus. The meso blast is formed from the entoderm at the lips of the blastopore, and makes its appearance as a series of paired hollow outgrowths from the cavity of the archenteron.-(Journ. microsc. soc. Lond., Feb., 1883, 52.) c. S. M. [453 Eyes of Scorpio and Limulus. - E. Ray Lankester and A. G. Bourne have investigated the minute structure of the eyes in Limulus and Scorpio, and conclude that the results, which are given in detail and with elaborate illustrations, confirm the opinion previously expressed by Lankester, that the scorpions and king-crabs are closely allied representatives of the class Arachnida. The compound lateral eyes of Limulus are compared with the lateral groups of simple eyes in scorpions, and found to agree in the most essential points. The central eyes of Limulus are found to agree still more closely with those of scorpions.-(Quart. journ. microsc. sc., Jan., 1883.) s. I. s. Insects. [454 The scales of Coleoptera.-Mr. George Dimmock described the scales, or scale-like hairs, of a number of beetles, and considered the effects of scales on the coloration of these insects, and the modes of coloration of scales themselves. Scale-like hairs of Cicindela, Psiloptera, Anthrenus, Hoplia, Polyphylla, Valgus, Chalcolepidius, Alaus, an undetermined genus of European Elateridae, Ptinus, Clytus, and Entimus, were described. This adds the Elateridae and Cerambycidae to the families which were already recorded as sometimes owing their figuration to a scale-covering. The influence of air in producing silvery and milky whiteness in insects and in their scales was also discussed. The author adopted Dr. H. A. Hagen's division of the colors of insects into optical' and 'natural' colors of two sorts, —‘dermal' and 'hypodermal,' - and gave a table of treatment with reagents, to enable one to distinguish these colors in scales under the microscope. As far as examined, scales of Lepidoptera owed their coloration to optical and hypodermal colors; scales of Coleoptera, to optical and dermal colors; although too much stress must not be put upon the differences between dermal and hypodermal colors. The paper, which will appear in full in Psyche, was illustrated by numerous figures and microscopic preparations. In conclusion, a mode of collecting together scales, or other minute objects of similar nature, on a microscope slide, was exhibited. This consists in putting the scales in a drop of some quickly evaporating substance-chloroform is best for most purposes-on the slide. The scales will form in a kind of whirlpool, nearly all the scales finally settling down, as the liquid evaporates, in one place on the slide. This mode of operating is very convenient; and, by inclining the slide gently, the mass of floating scales can be made to settle on the exact centre of the glass. One part of Canada balsam to several hundred of chloroform will cause them to stick to the slide.-(Cambr. ent. club; meeting March 9.) [455 Mimicry of humming-birds by moths. - The striking resemblance in size, form, and movements, of the South-American Macroglossa Titan to humming-birds, which has been noticed by Bates, Fritz Müller, and others, and referred to the similarity in their habits, is believed by Dr. Krause to be a case of protective mimicry; the moths benefiting by their resemblance to the birds, which have few winged enemies. The closeness of the resemblance is supposed also to protect the moths from the humming-birds, which always give chase when they recognize them. To do away with an objection that might be urged from the similar appearance of European Macroglossae, which have no Trochilidae to imitate, it is assumed either that these birds occurred in Europe in late tertiary times, or that the moths are recent importations from the new world. — (Kosmos, Nov.) [456 W. T. (Economic entomology.) The regulative action of birds upon insect oscillations. -The question "Do birds sometimes vary their diet so far as to neglect their more usual food, and take extraordinary numbers of those species of insects, which, for any reason, become superabundant for a time?" is answered by Prof. Forbes in a very conclusive manner. He selected an orchard which had been for some years badly infested by cankerworms; shot a considerable number of birds therein for two successive years (54 birds of 24 species the first year, and 92 birds of 31 species the second year), representing nearly all the kinds seen in the orchard; made full notes of the relative abundance of the species; examined carefully the contents of the stomachs obtained, with reference not only to the presence of canker-worms, but of all other insects as well; and tabulated the results. The summaries on these tables are brought into comparison with those derived from birds of the same species shot in ordinary situations during the same month. Thirty-six species of birds were taken in the infested orchard. 72% of the species, and 60% of the specimens, had eaten canker-worms. 35% of all the food eaten by all the birds was cankerworms. The comparisons made between the food of these birds and that of birds shot in other situations show, that the large proportion of the food which the canker-worms constituted, in one case was compensated by a general diminution of the ratios of all the other kinds of food, and not by a neglect of one or two alone. Hence the birds, in checking the increase of the canker-worm, were not tending to allow an undue increase of any other species of insect. — (Bull. Ill. state lab., No. 6, Dec., 1882.) J. H. C. [457 Corn-root worm.- The eggs of Diabrotica longicornis have been discovered by Prof. Forbes. They are laid in September and October in the ground upon or about the roots of corn, and probably do not hatch until the following May or June. The best means of checking the increase of this insect is, therefore, rotation of crops. (Prairie farmer, Dec. 30, 1882.) J. H. C. [458 - |