GEODESY.

The lake survey. There has just been issued by the chief of engineers, in a quarto of 920 pp. with thirty plates, a detailed report of the operations in the prosecution of the survey of the Great Lakes. This important work is now finished, and the report presents in a comprehensive manner the methods used and results obtained. While omitting the vast amount of uninteresting detail with which such works are usually encumbered, all important features are given mention; and the whole volume is indexed with such care that any particular subject may be instantly found. The report starts with a historical account of the survey, from its inception in 1841, to its completion; gives a synopsis of the work accomplished under the various officers who from time to time have had charge of the survey; gives an account of the standards of length upon which the surveys depend, of the measuring-bars used and methods of using them, and of the results obtained both in the measurement of the base lines and in the results of their connection by triangulation, and of the geodetic and astronomical work. The part devoted to the discussion of the base apparatus will be found of special interest to geodeticians. Full account is given of the determination of the constants of the apparatus used, and of the co-efficients of expansion. Also there is a discussion of the 'set' of a zinc bar when heated. A portion of the book is devoted to the consideration of the mean levels of the Great Lakes, and the methods by which the results were obtained. The question of tides in the lakes had been previously considered (Report of chief of engineers, 1872). The tides are perceptible, but of scientific rather than practical importance, the maximum being less than two inches. (Professional papers, corps of engineers, no. 24.) [346

H. W. B.

Elliptic functions. - This is the first part of a paper by Otto Rausenberger, in which he introduces a new idea into the theory of elliptic functions. Instead of, as usual, considering doubly periodic elliptic functions, he considers that an advantage is gained by considering what may be called transcendants, with simply multiplicate periods (einfacher multiplicatorischer periode); that is, functions satisfying the equation f (px) = f(x). The notation which he has adopted is made to conform as nearly as possible with that employed by Königsberger in his 'Vorlesungen über die theorie der elliptischen functionen.'

He defines certain functions, 70, 71, 72, 73, which are analogous to the ordinary theta-functions, and gives the values of functions S (p, x), C (p, x), D (p, x), which correspond in the ordinary notation to sn x, en x, dn x, in terms of these 7-functions. The equations are identical in form with those giving sn x, etc., in terms of the @-functions. In conclusion a discussion of some of the properties of multiplicate periodic functions is given.—(Journ. reine angew. math., xciii.) T. c. [350

Binary quintics. - An extensive discussion of the Hessian of the binary quintic is given by Mr. F. Lindemann. The expressions for the invariants and quadratic covariants of this sextic covariant, in terms of the invariants and covariants of the quintic to which it belongs, are obtained, and a relation found to exist between them, which is the necessary and sufficient condition that a given sextic may be the Hessian of a quintic. The typical expression of the Hessian by means of its quadratic covariants is next found. In the course of obtaining this, it is observed, that, when a certain invariantive condition is fulfilled, the quintic is reducible to a known soluble form. The remainder of the article contains the investigation of the peculiarities which attach to the Hessian on the supposition of any peculiarity in the quintic, and vice versâ; the determination of a quintic whose Hessian is given; and, finally, a geometrical interpretation of the condition satisfied by any sextic which is the Hessian of a quintic. (Math. ann., xxi. 1, 1883.) F. F. [351

Theory of numbers. — In an article on powerresidues (potenzreste) F. Hofmann employs the device of representing the residues of the successive powers of a number with respect to a prime-number modulus as the successive vertices of a regular polygon inscribed in a circle, to prove Gauss's theorems concerning the sums of the primitive roots of the binomial congruence, a -1 (mod. p). He makes some remarks on binomial equations, and their connection with binomial congruences. (Math. ann., XX. 4, 1882.) F. F. [352

p-1

PHYSICS. Acoustics.

Range of sounds in air. - Allard has deduced a formula for the intensity of a sound in terms of the work done in producing it (T), the rate of vibration (n), and the extreme range (x). The table given by him shows that the intensity of the sound in air decreases more rapidly than is indicated by the law of inverse squares. At the extreme range, all the sounds are reduced to the same intensity; while the T

values of vary, for the six instruments used, from x2

0.10 to 13.46.

range for the extent of an octave is slight. - (Comptes rendus, Nov. 22, 1882.) C. R. C. [353

Heat.

Relation between latent heat, specific heat, and volume.-It is pointed out by Mr. Trouton that the latent heat of gasification at constant pressure of any body, divided by the product of the rélative volume of the gas and the specific heat of the body, is approximately constant. This constant is calculated for many substances. The only marked exceptions are water and acetic acid. (Nature, xxvii., No. 691.) C. B. P.

7

[354 Exception to the second law of thermodynamics. An ingenious method has been devised by Prof. H. T. Eddy to show that radiant heat is an exception to the second law of thermodynamics. The method is based upon the fact that heat is radiated, not instantaneously, but with a finite velocity, and consequently it is possible for occurrences to take place, during the exchange of radiations between two bodies, such as essentially to alter the ultimate distribution of heat. If three screens, composed of some perfectly reflecting material, are provided with suitable apertures, and are placed parallel between two radiating bodies, velocities can be communicated to the screens such that radiations from the first body will pass through the apertures to the second body, while the radiations from the second body will be intercepted, and reflected back. Thus, if the temperature of the first body is less than that of the second, heat can be transmitted from a colder to a hotter body without compensation, and without the expenditure of work.

The axiom of Clausius, that heat cannot of itself pass from a colder to a hotter body, and the similar axiom of Thomson, are thus only true with regard to radiations, if the velocity of radiation is infinite.

The arrangement employed by Prof. Eddy, which he calls the radiation siren,' proves that we can no longer regard the law of dissipation of energy of universal validity, and we cannot accept the principle of Clausius, that the entropy of the universe tends to a maximum. (Proc. Amer. phil. soc., xx. No. 112.) C. B. P. [355

Electricity.

Electric railways.-Professor Ayrton, in a lecture at the Royal institution, showed that the weight of a train on an electric railway would be comparatively small, because stationary engines would be used, and each pair of wheels on all the cars could be used as drivers. Hitherto the objection to the extension of electric railways has been, that the insulation of the rails used as part of the motive circuit was imperfect. Prof. Perry and the lecturer have devised an arrangement by which the passing train depresses a series of corrugated steel disks mounted on stands some inches above the track, and thus makes a carefully protected contact with the insulated main cables on each side; at the same time putting a temporary earth fault in an auxiliary wire, which records at the station the progress of the train. The track is divided into sections, from each of which the current is cut out while a train is on the section next in advance. If a train enters the section so cut out, its electromotors are shunted, so as to powerfully resist the motion of the train. The electric lighting of the cars is kept up, in such a contingency, by the automatic switching-in of Faure batteries.-(Nature, Jan. 11.) J. T.

[356 Wimshurst's electrical machine. -Two circuar glass plates 144 inches in diameter, and of an

inch apart, with 12 brass strips cemented on the outside of each at equal angular intervals, rotate in opposite directions on the same axis. Opposite strips on the same plate are connected once in each revolution by a curved metallic rod terminated with brushes. The electricity is collected by combs opposite the horizontal diameter. With the instrument described, under ordinary atmospheric conditions, a 44-inch spark was obtained once in every 2 revolutions. The only apparent exciting cause is the friction of the air between the plates. (Engineering, Jan. 5.) J. T. [357

New telephone receiver.-S. P. Thompson has devised an improvement on the instrument of Philip Reis, who utilized the sound emitted by a magnetized bar due to fluctuations in the magnetizing circuit. The improvement consists in making the magnetized core slender and subject to adjustable tension, and attaching one end to a suitable vibrating plate. In one form two cores are used, one being of nickel, which contracts when magnetized; the opposite movements being used to increase the distortion of the membrane. It is claimed that articulation, especially of sibilants and certain other consonants, is more distinct with this than with the common receiver.(Engineering, Jan. 26.) J. T. [358

Value of the Siemens unit.-E. Dorn, by a modification of Weber's second method by which he eliminates the influence of terrestrial magnetism, establishes the relation

Separation of barium from strontium or calcium by potassium chromate.-J. Merscherzerski finds that barium chromate is soluble in 23,000 parts water, more soluble in acetic acid, and it has a great tendency to carry down other salts from the solution in which it is precipitated. Since strontium chromate requires 840 parts water for solution, it would be precipitated in a solution containing more than one per cent. The author therefore concludes that this method affords a convenient and sufficiently accurate means for a qualitative separation; but it cannot be relied upon for quantitative purposes. (Zeitschr. anal. chem., 1882, 399.) C. F. M. [361 1 These results depend on the ratio, given by Kohlrausch, B. A. unit = 1.0493.

8. unit

The

Testing for barium or sulphuric acid. minimum strength of a solution of barium chloride in which barium can be detected with certainty, according to S. Pickering, is 1 part barium in 833,000 parts water; and the re-action is equally delicate with sulphuric acid or ammonium sulphate. The precipitation was observed against a black background by means of an artificial light placed almost vertically above the test-tube.(Chem. news, xlvi. 223.) C. F. M. [362 Estimation of sulphur in iron and steel. — G. Craig meets with good results by passing the gases evolved with hydrochloric acid through an ammoniacal solution of hydrogen peroxide. (Chem. news, xlvi. 199.) C. F. M. [363

Detection and estimation of titanium. — A. Weller finds that the change in color produced when titanic acid is formed by oxidation of the sulphate with hydrogen peroxide is sufficiently delicate to render the re-action a suitable means for the determination of titanium. - (Berichte deutsch. chem. gesellsch., xv. 2592.) C. F. M. [364

Estimation of titanic acid in presence of iron. -A method proposed by Pasani for the volumetric analysis of a solution containing titanic acid and iron depended upon his observation that the acid oxide of titanium (TiO2), when reduced to the sesquioxide (TiO3) by nascent hydrogen, could be completely oxidized by potassium permanganate, even in presence of iron in the ferrous condition. According to E. Wiegand, this method is incapable of giving constant results. He finds that ferrous oxide undergoes partial oxidation before oxidation of the titanic sesquioxide is complete, and therefore infers that ferric oxide and titanium sesquioxide can exist in the same solution. · (Zeitschr. fur anal. chem., 1882, 510.) C. F. M.

[365

Volumetric analysis of peroxides.-A comparison of Bunsen's and Mohr's methods for the determination of available oxygen in peroxides by W. Diehl shows that digestion with hydrochloric acid and potassium iodide, recommended by Mohr, gives as exact results as the distillation in Bunsen's method. Digestion with acetic instead of hydrochloric acid affects as complete decomposition of manganese dioxide, either freshly prepared or in pyrolusite; and at the same time potassium iodide is without action upon ferric acetate. The available oxygen and the percentage of iron in manganese dioxide may therefore be ascertained by two determinations, in one of which hydrochloric acid is used, and in the other acetic acid. In lead peroxide the available oxygen may be as accurately determined by digestion with acetic acid and potassium iodide as by Bunsen's method. - (Dingler's polytechn. journ., 246, 196.) C. F. M. [366

METALLURGY.

The Siemens direct process. This consists in heating mixed fine iron-ore and coal in a horizontal, slowly revolving cylinder. The iron forms a sponge ready for rolling, while the silica and earthy impurities form a slag, which removes the hurtful sulphur and phosphorus from the iron. Mr. James Davis of Landore, Wales, gives his experience. He makes one ton of wrought iron with one ton of gas-producer coal, reduces the sulphur to a trace, and the phosphorus to .05 per cent. He finds magnesia bricks to stand the best. In 32 days 21 hours net working time, with 200 heats, using 200 tons of ore and 120 tons hammer scale, he made 217 tons 5 cwt. of blooms. (Eng. and min. journ., Jan. 6, 1883.)

Recovery of precious metals from slags.— A patent has been obtained by Mr. Richard Pearce of Denver, on an improvement in smelting gold and silver ores. The process consists in throwing upon the slags, as soon as the charge is perfectly melted, a fine-powdered oxide of copper or roasted copper matte. The furnace is then closed a short time. A reaction takes place, and a matte descends, thereby robbing the slag of its precious metals. For a charge of 3 tons of ore, 30 lbs. of oxide of copper are needed. (Min. and sc. press, Dec. 16, 1882.) [368

R. H. R.

Basic open-hearth steel process. - Mr. O. T. Tellander has described the adaptation of this process at the Alexandrowsky steel-works, St. Petersburg, Russia. The steel is made from pig-iron, scrap-iron, spiegel, and ferro-manganese, which are melted in the usual Siemens-Martin furnace. The special feature of the basic process consists in lining the furnace with bricks made of dolomite mixed with 18 per cent of coal-tar. The joint between this lining and the outer Dinas bricks is made by a layer of chrome-iron-ore and coal-tar. A mixture containing .5 per cent of phosphorus yields steel with an average of only .04 per cent. The sulphur is also reduced as much, while the silicon is almost entirely removed. (Eng. and min. journ., Jan. 13, 1883.) R. H. R. [369

1. Mature seeds of common cultivated plants suffer no diminution of the proportion of seeds capable of sprouting, if soaked twelve hours in water, and then dried at ordinary temperatures. Some samples of peas constituted exceptions to this rule. Soaking twenty-four hours, and then drying, usually caused a slight decrease in the percentage of seed which germinated.

2. Some seeds even survive an interruption of germination in its first stages. The radicle dies, but is replaced by adventitious roots. The plumule is more enduring: even when the terminal bud is destroyed, lateral buds may develop.

3. The proportion of seeds capable of regermination is, in general, inversely proportional to the extent to which germination has progressed.

Mono

4. The extent to which the first germination_may be carried varies in different kinds of seeds. cotyledonous seeds seem, in general, to withstand this treatment better than di-cotyledonous.

5. In view of the fact that such seeds germinate only under the most favorable conditions, the use of seed that has once been germinated is not to be recommended in practice.—(Landw. versuchs-stat., xxviii. 51.) H. P. A.

[370 Prevention of potato-disease. According to Jensen, this disease, which is caused by a fungus (Peronospora infestans, Tul.), attacks first the tops, and is conveyed to the tubers by means of spores washed into the soil by rain. He therefore proposes to prevent this by running a plough between the rows, so as to throw up a furrow upon the top of the hills, while at the same time the tops are bent over so as to hang above the neighboring furrow. This should be done at least as soon as the disease shows itself on the tops; usually by the middle of August. In this way the washing of the spores into the hill is prevented. Furthermore, the potatoes should not be dug for at least two or three weeks after the tops are entirely wilted, to avoid infection from the latter. Field experiments with this method gave very favora

ble results. (Biedermann's centr.-blatt., 1882, 755.)

H. P. A.

He

[371 GEOLOGY. Impressions on Potsdam sandstone. - At the meeting of the Natural history society of Montreal, Feb. 26, Mr. Walter Ferrier exhibited specimens of some new trails and impressions of animals from the Potsdam of Rainbow Falls, near Au Sable chasm on Lake Champlain. One of them is a cast of two narrow furrows about a quarter of an inch apart, with a rim of punctiform impressions about an inch distant at either side. This impression is repeated in two places on a ripple-marked slab. It may be the track of a trilobite with two prominent spines on the pygidium, possibly of some species of Dikellocephalus. Another is a trail about an inch in width, marked with transverse furrows and ridges, perfectly simple, and without any median ridge. In this last respect they differ from the trails known as Rurichnites, Cruziana, Arthrichnites (Arthrophycus), and Traena. They resemble, though on a larger scale, impressions from the Erian sandstone of Gaspé, of which a slab from the collection of Dr. Dawson was exhibited for comparison. Such impressions, destitute of a central ridge, may have been made by gasteropods or by worms without any abdominal furrow. The name Clydichnites (wave-tracks) has been proposed for them by Dr. Dawson; and the Potsdam and Erian forms must belong to two distinct species. -J. W. D. [372 Newfoundland geology.—The report of progress of the Geological survey of Newfoundland for the year 1881 contains a report of Mr. J. P. Howley on the structure of the peninsula of Avalon. finds that the major part of the peninsula is made up of the various divisions of the Huronian or Intermediate system, as given in the report for 1868, resting upon a nucleus of gneiss, and succeeded by the fossiliferous beds of the primordial Silurian or Taconic, which skirt the shores of the bays, and form most of the islands therein. In division d of the Huronian system the fossils Aspidella terranovica and Arenicolites spiralis occur. He recognizes two large intrusive masses of plutonic rocks, one in the eastern, and the other in the western peninsula. That in the eastern peninsula he considers the older, as it has not affected the primordial strata, as has been the case in the western peninsula. The eruptive mass between Salmon cove and Collier's bay he considers as having been formed prior to the deposit of the higher members of the Huronian system, as the strata intersected are confined to the lower divisions, a and b. Mr. Howley failed to discover, in the auriferous quartz-veins of division c, a single example of visible gold. Some copper ores were found, mostly in divisions a and b of the Huronian system. Near Little Placentia, some argentiferous galenite occurred, which yielded, on analysis, 159 ounces of silver to the ton (2,240 pounds) of ore. Accompanying the report is an appendix with three plates, containing descriptions and figures of primordial fossils, by the late E. Billings. These figures and descriptions have already been published (Geol. surv. Can., pal. foss., 1874, ii. 1). A geological map on a scale of four miles to the inch, and showing very plainly the distribution of the formations, accompanies this report; also a section-map showing the corrugations effecting the stratification of the Huronian formation near Brigus, Conception bay, on a scale of four inches to a mile, surveyed by J. P. Howley. — J. B. M. Lithology.

[373

In the present paper the results of an extended study of the plagioclase rocks and phonolites of the Mecklenburg drift is given by one of the prominent young German lithologists, Dr. Eugen Ĝeinitz, of the Rostock university. Geinitz' method consists in examining thin sections of the rocks found in the drift, and comparing them with the descriptions given by the Scandinavian lithologists of rocks known in situ in that peninsula. In this way various basalts, diabases, gabbros, diorites, and phonolites are referred to certain localities in Sweden, whence they are supposed to have been derived. Interesting results can be obtained by such methods; but they are often uncertain, since it cannot be predicated that rocks of the same character do not exist, or have not existed, in the intermediate drift or water-covered

areas.

The paper is a valuable one on account of the extended descriptions of the rocks examined. - (Nova acta acad. leop.-carol., xlv. 35.) M. E. W.

[374 Hypersthene-andesite. The chief pyroxene of an apparently typical augite-andesite' from Buffalo Peaks, Col., was found by Whitman Cross to be hypersthene, both from its optical properties and chemical composition. The mineral was isolated for analysis by treating the rock powder with HF, which dissolved the feldspar, glass base, and finally the augite, leaving only the hypersthene (richer in iron than augite) and ore particles. The latter, being magnetite, were separated by a small magnet. The microscopic examination of many European and American augite-andesites of the same type seems to prove that they, likewise, contain more rhombic pyroxene (hypersthene) than augite; and Cross claims that they should be separated from other andesites, and called 'hypersthene-andesites.' Nearly all other so-called augite-andesites have more of the trachytic habitus, and are so nearly related to hornblende and mica-bearing andesites, that, according to the writer, they cannot be consistently separated, and considered as a distinct group. Should the determination of hypersthene in this sub-group of the andesites be confirmed, a very interesting, widely distributed, and well defined rock-type will have been discovered. (Amer. journ. sc., Feb., 1883.) s. F. E.

METEOROLOGY.

[375

Iowa weather service. Mr. Gustavus Hinrichs has issued an almanac for 1883, under the title of Iowa weather service annual, giving, in addition to the ordinary calendar, a summary statement of the climate of Iowa, illustrated by several diagrams. The mean temperature for Iowa City is, for the winter months, 250; for the summer, 72°. The barometer is highest in December, lowest in April and June. The winds are strongest in March and April, being mostly westerly or north-westerly in winter, often easterly in spring, southerly or calm in summer, and westerly in autumn. Besides the general cyclonic storms, Iowa has the blizzard,' an intensely cold, high wind following a winter thunder-storm; the tornado, commonest in June, but occurring from March to October; and the squall, a sudden north-westerly wind with heavy clouds and rain, following sultry weather with light southerly winds. Precipitation is greatest from June to August, and least in December. It is shown on monthly maps compiled from 26,082 measures from 1876 to 1880. It is least in the northwest (26), heaviest in the south (36") and east (38), and seems to be "dependent on the distribution of

the timber in the State, being greatest where the timber is most abundant."-W. M. D. [376

GEOGRAPHY.

(South America.)

Brazilian coast.-R. A. Hehl describes the physical peculiarities of this coast, between 21° and 23° south latitude, under the headings of shore-lagoons, rivers, neighboring mountain ranges, and lowlands. - (Peterm. mittheil., 1882, 443.) W. M. D. [377

Fontana's unsuccessful search for Crevaux. The Argentine expedition under Fontana, sent last July in search of the remains of Crevaux and his party, who were lost on the Pilcomayo some months earlier, has returned to Buenos Aires without any information of the unfortunate explorers. It is concluded that any expedition, to be successful, must attempt the river from its head waters, whence a voyage down stream would require only four or five months; while, in ascending the river, at least ten months would be needed, and many great difficulties would be encountered. (Comptes rendus soc. géogr. Paris, 1882, 466.) [378

W. M. D.

Rumor of Crevaux's survival.-M. Milhôme, a French settler in the province of Tarija, Bolivia, wrote last October that he was convinced that some of Crevaux's party were still alive, and held as slaves by the Tobas Indians. He had seen one of the party, named Zeballos, who had escaped the reported massacre, and who had seen another, named Blanco, kept as a prisoner. Moreover a cacique had brought information to Milhôme that the Indians had some white men as prisoners, and were learning the use of arms from them. (Compt. rend. soc. géogr. Paris, 1883.) [379

W. M. D.

(Africa.)

Wissmann's trip across Africa. At a meeting of the Khedival geographical society (Cairo) on Jan. 19, Lieut. Wissmann read a paper on his recent journey across equatorial Africa, stating, that, in company with Dr. Pogge, he had left Mukenge's town in the Tushilange country on Dec. 1, 1881, and crossed an unexplored country to the eastward as far as the Arab settlement Nyangwe, on the Lualaba, arriving there April 16, 1882. The route led them across the Lulua, Muansangoma, Lubilash, and Lomani rivers; and to the east of the last they came upon the route that Cameron had followed westward nearly ten years before. None of the large lakes previously reported in this region were found or heard of, except the Munkamba, which proves to be a small lakelet hardly three miles in length. It is fed by springs, and has no outlet, and lies at an altitude of 2,230 feet, in lat. 5° 45' S., long. 22° 55′ E. Dr. Pogge at once returned westward from Nyangwe, but has not yet been heard from. Wissmann, after staying two months on the Lualaba, started eastward by a beaten track to Lake Tanganyika, which he crossed to Udjidji, and then passed by way of Tabora to Zanzibar on Nov. 17. His entire journey from sea to sea occupied twenty-two months. (Athenaeum, Feb. 3, 1883.) w. M. D. [380 Pogge and Wissmann.-B. Förster prepares for an account of the journey of these explorers across the Kongo basin and the lake-district by a review of the results of the earlier journeys in the same field by Livingstone (1852-54), Cameron (1874), Stanley (1876), and the travellers of the German-African association in the southern Kongo basin, within the last ten years. This is followed by a summary of Pogge and Wissmann's observations as far as Mukenge. (Ausland, 1883, 33, 117.) W. M. D. [381

(Atlantic Ocean.)

Eruption of Teneriffe. C. Piazzi Smyth learns from private advices, that for several months past there has been no snow on the upper part of the peak of Teneriffe, although the rest of the high land has been whitened, as is usual at this season, and that more recently (in January?) 'fire, like three great bonfires,' had been seen on the summit of the peak, and a lava-stream had begun to flow down it. Previous eruptions are recorded about 1582; again in 1703 from the side of the peak, giving forth lavas that threatened the town of Guimar, on the south, and destroyed Garachico and filled its bay, on the north; and, finally, in 1798, from the western side of the mountain away from the peak. —(Nature, Feb. 1, 1883.) w. M. D. [382

BOTANY.

Action of fungi on cane-sugar.-M. Gayon, in experimenting with Mucor circinelloides, found, that, in the absence of free oxygen, this fungus forms spherical cells, which produce alcoholic fermentation in beer-wort, grape-juice, and solutions of glucose and levulose, precisely like brewer's yeast; but, unlike that ferment, the Mucor produces no change in canesugar. But if a band of paper impregnated with invertine, or a fungus capable of producing invertine, as Penicillium, is introduced into a solution of canesugar, the Mucor is then able to produce an alcoholic fermentation. It is now known that several species of Mucor are not able to invert cane-sugar; and the same is true of Saccharomyces apiculatus. M. Gayon suggests an ingenious method of separating cane-sugar from other sugars, as in molasses, by fermenting with the Mucor, which leaves the cane-sugar unchanged and crystallizable, while, if brewer's yeast were used, all the sugar would disappear. (Ann. sc. nat., xiv. 46.) w. G. F. [383

Development of Ascomycetes. — In order to decide the question of the sexuality of the Ascomycetes, C. Fisch has studied the formation of the asci and perithecia in the Pyrenomycetes. The principal genera studied were Polystigma, Xylaria, and Claviceps. In the first-named genus he finds that there are ascogons and trichogynes, which bear a strong resemblance to the organs of the same name found by Stahl in the lichen genus Collema; but, although spermogonia exist in Polystigma, Fisch could not be certain of a union of spermatia with the trichogyne, as was seen by Stahl in Collema. In Xylaria and Claviceps, however, he could find no evidences of sexuality, and the asci arose directly from the hyphae. Adopting the view advanced by DeBary in his paper on Saprolegniaceae, Fisch inclines to the belief that in the Pyrenomycetes we have a family in which apogamy exists as a rule, although in some cases, as in Polystigma, there is a connection with families in which there is a distinct sexuality. (Bot. zeit., Dec., 1882, Nos. 49-51.) W. G. F. [384

The

Structure and movements of leaves. The relations between particular structural features in certain leaves to the phenomena of nyctitropic or sleep movements, and to those of movements following shock, must receive increased attention on account of recent papers by Gardiner and Cunningham. former gave an account of his discovery (Quart. journ. of micr. sc., Oct., 1882) that the protoplasm in adjacent cells of the pulvinus, or cushion at the base of the petiole, of Mimosa pudica, is continuous; the continuity being maintained by protoplasmic filaments which pass through pits in the cell-walls. In a more recent paper (Proc. roy. soc., Nov., 1882) Mr. · Gardiner states that he has now found the same pe