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solved, in spite of much patient work by Pickering, Gladstone, Ostwald, and others. It, however, appears probable that in many cases the salt is decomposed by the mere act of solution partly or entirely into its constituents. Mr. Crookes has found that under the influence of an electric discharge in a vacuum tube metals can be slowly dissipated or evaporated," the current causing a slow transference of the metallic molecules from one pole to another. Different metals show different rates of "evaporation," some being readily affected, while others are almost unacted upon. So marked is this difference, that an alloy can sometimes be separated into its constituents by this means; thus, if the purple alloy of gold and aluminium (to which allusion has been already made) is employed, the gold is "evaporated," and the aluminium left behind. By suitable means the evaporated metals can be deposited in films of varying thickness, showing brilliant prismatic colours. Gold, silver, and platinum can be thus volatilised, but magnesium, like aluminium, is unaffected. The phenomenon is clearly not due to an effect of temperature, since magnesium is readily melted and volatilised by heat, while platinum can only be melted with extreme difficulty. Professor Hopkinson has shown that at a temperature of — 30° C. the density of a nickel steel containing 22 per cent. of nickel is reduced by nearly 2 per cent., which is equivalent to saying that this alloy expands in falling from 0° to - 30° by that amount. As nickel steel is advocated for use in armourplating, this observation is of great importance. As Professor Roberts Austen has shown, a ship in which such armour plates were used would incur strains sufficient to totally destroy it if it were exposed to the low temperature of the polar regions.

BIOLOGY.

Attention has been drawn in a former year to the modifications that Darwin's theory of coral reefs has undergone, owing to the observations of Murray and others. Recent discoveries by Mr. Bassett Smith are also of importance in this connection. Mr. Smith has found from dredgings on the Macclesfield and Tizard banks in the China Sea, that no less than nineteen species of corals live and grow at depths from thirty-one to forty-five fathoms. As thirty fathoms has been previously considered the maximum depth for these corals, this greater range shows that all the conditions of coral reef building are still unknown. Similarly, five species of madrepore were found at depths varying from twenty to twenty-seven fathoms, though no species of this genus was previously known to live below ten fathoms. It is to Darwin that we owe the recognition of the importance of the work done by earthworms, but the efforts of our English worms appear singularly small when compared with that of some African genera. Thus, Mr. Alvan Millson has estimated that the large earthworm found in Yorubaland brings to the surface over 60,000 tons of subsoil per square mile. The improved fertility of the soil is so clearly marked, that the natives do not attempt to cultivate those spots where no traces of worm action are manifest. The influence of external conditions on development has been strikingly shown by E. Wassmann's experiments on ants. By warming nests of Formica sanguinea and Formica fusca through successive winters, he has been able to produce parthenogenesis in both species. The eggs laid by these abnormally developed workers did not, however, attain full development, being devoured by the ants. Wassmann agrees with Lubbock, that ants hear, in

opposition to the opinion of Forel and others. The experiments of Dr. Louis Robinson on the grasping power of infants are of great interest. Dr. Robinson finds that extremely young children, even newly born babes, have very great muscular power in the hands. One infant only a few hours old hung by one hand to a stick for nearly three minutes, and this power of holding on is only gradually lost with the increasing weight of the child. Such a power points to an original arboreal existence of the race, a condition which Dr. Robinson has further illustrated by an ingenious explanation of the apparently useless hair patches under the arms. The comparison of the so-called liver of invertebrates with that organ in the vertebrates has shown, as the result of various researches, that while the vertebrate liver is primarily an organ of nutrition for the embryo, altered in post-embryonic life into an organ of excretion, that of the invertebrate is essentially a gland secreting a digestive fluid containing ferments. It has also been shown by Viault and Müntz that the proportion of oxygen in the blood is practically independent of the pressure of the air, and is not appreciably less at high levels than what it is at lower elevations. With greater heights the blood contains more red corpuscles, and is correspondingly richer in hæmoglobin, this greater richness compensating almost completely for the reduced pressure of the air. In the respiration of plants, Aubert has noticed that in a moderate light the cactus exhales both oxygen and carbonic acid, the thin layer of chlorophyll cells not being capable, except in direct sunlight, of decomposing all the carbonic acid gas excreted by the colourless parenchyma. The physiological action of drugs is always a source of interest, more especially when the results of experiment show that the same drug exerts different effects on different animals. Thus, injections of morphine in cats produce a condition of excitement, and not narcotism, as in man. Schöndorff, Genth, and others have found that by drinking large quantities of water, the excretion of nitrogen from the system is increased; and Mr. Dymond has ascribed the sedative action of lettuce to minute traces of the poisonous alkaloid hyoscyamine. If this observation is correct, this is the first instance in which an alkaloid of this kind has been found in any natural order but the solanaceæ. The question of immunity from disease has been studied, as in previous years, by a large number of workers. Mr. E. H. Hankin states that from results obtained in Koch's laboratory it seems to be clearly established that the blood of an animal which is naturally proof against a disease, or has been rendered proof by inoculation, can be used with success to cure the same disease in another animal. This may be in part due to the circumstance that blood serum exerts a distinct germicidal action, a fact which from repeated observations may be accepted as established. Among new germicides an infusion of coffee has been found to possess considerable merits, as the bacilli of erysipelas, typhoid, or cholera can only live in it for a short time. The widespread outbreak of influenza has caused frequent search to be made for the isolation and identification of the microbe which produces the disease, but so far the results obtained have been unimportant. Additions to our knowledge of larger forms of life during the past year have, as some compensation, been more abundant than usual. Chief among these is the discovery of a new member of the scanty family of marsupials. This is the pouched mole, Noctoryctes typhlops, which was first observed by Mr. Coulthard on the banks of the Frew river in South Australia, and has been also noticed in certain other places on the overland telegraph route. It inhabits sandy soils, and is able to construct burrows with great rapidity. Several new and interesting forms of animal life have

been described by Emin Pasha from Central Africa, and Dr. Peters also reports the discovery of new mammals belonging to the cetacea from the Albert Nyanza lake. Certain strongly marked affinities have been pointed out by Professor Ray Lankester between the giraffe and ruminants of the Pliocene Age, and thereby some light is thrown on the difficult question of the origin of the widely divergent group to which that animal belongs. The persistency with which even apparently trivial markings in the animal kingdom are retained has been well illustrated by Francis Galton, who finds from a wide series of observations that the lines on the thumb remain so remarkably constant for each individual, that they can be used as a means of identification even after a lapse of years. Some interesting experiments on growing plants have been made by Professor F. Darwin. If a plant is subjected to sudden change of position at regular intervals of time, it acquires a tendency to alter its position rhythmically in adjustment to the movement it has under. gone; and when this tendency is established, this rhythmical adjustment continues for some time after the originally exciting cause is removed. Professor S. H. Vines has found, in opposition to the opinion of Wortmann, that many, if not all green leaves, contain traces of a ferment capable of converting starch into sugar, this ferment being probably secreted by the protoplasm of the plant. The curious digestive power possessed by many insecteating plants is said by some observers to be due to the action of bacteria converting the objects seized into a condition in which absorption by the plant tissues can take place. A curious variation in the period of flowering has been noticed in the hazel by Mr. F. Mechan. In this country both the male and female flowers come to maturity at the same time, but in America, where changes of temperature are greater and more rapid, the male flowers mature first if a sudden spell of heat occurs, but the female flowers appear first if mild and humid weather sets in at the usual season of inflores

cence.

Mention has been previously made of Metschnikoff's theory of phagocytosis on the destruction of bacteria by their inclusion and digestion within certain cells known as leucocytes. It is to this process, according to Metschnikoff, that an animal owes its immunity from a disease or its power of recovery from an attack. These views have not, however, been readily accepted, and at the recent International Congress of Hygiene, held in London, the whole question was made the subject of debate, and much new evidence was adduced. Metschnikoff's opponents would ascribe a protective influence against disease not to the action of a leucocyte, but to the presence of some substance in blood serum. This substance Mr. E. H. Hankin says is a ferment like proteid. The fact that serum exercises an unfavourable influence on bacteria is undoubted, but while a moderate warmth (37° C.) facilitates the destruction of bacteria, a heat of 52° C. for six hours, or of 55° C. for half an hour effectually destroys all germicidal power the serum possesses. Fokker has found a similar power in milk. Fresh goat's milk, if unboiled, remains uncoagulated for two or four days, after the addition of a minute quantity of the bacterium, which produces lactic acid fermentation; but if the milk be first boiled, coagulation occurs within twenty-four hours. Freidenreich also observes that fresh milk reduces the number of the micro-organisms typical of typhoid and cholera if these are not present in too overpowering numbers, but if the milk be heated for twenty minutes to 68° or 70° C., this power is reduced or lost. The germicidal property resides in the skim milk and not in the cream.

Rats are well known to possess immunity from

attacks of anthrax, but Feser and Hankin find that in wild rats this immunity is lost if the animals be kept on purely vegetable diet; and Dr. Klein has shown that if rats be kept under anaesthetics after inoculation with anthrax they die of the disease. From these observations it would appear that the protective power resides mainly, if not entirely in the blood, and that to develop or maintain the germicidal power of the serum is the surest way to combat disease. In this connection the researches of Dr. Ehrlich on the action of ricin are of great value. Ricin is a highly poisonous alkaloid, but its effect on different animals varies considerably. If doses be given to guinea pigs and to mice in proportion to their body weight, the guinea pigs are by far the most affected. But animals can be rendered capable of bearing very large doses if the proportion of ricin given be gradually increased. Dr. Ehrlich states that when a mouse has been thus rendered proof against a poisonous dose, the immunity continues for six months afterwards, even if no ricin be given in the interval. He was able also to extract from the blood of mice which had been thus artificially fortified, a substance which, on inoculation, prevents ricin poisoning in others.

GEOLOGY.

Attention has frequently been drawn to the occurrence among living species in the South and South-East of Asia of representatives of genera which, though now extinct in Europe, flourished there during the Tertiary epoch. Two more such instances have been lately discovered. Professor Capellini has found at Cagliari the skull of a species of Tomistoma, a crocodilian genus to which belongs the living Gharial of Borneo; and Mr. Lyddeker has described a species of Trionyx from the Miocene strata of Malta allied to a species now found in India. Several startling discoveries have been announced from the United States. One of the most remarkable is the reported finding of human remains in Tuolumne County, California, with bones of the extinct mastodon and rhinoceros, and Tertiary plant remains in a bed of auriferous gravel under a layer of lava. Such a discovery, if authentic, would carry back the antiquity of man in America to a far earlier period than has been previously admitted. The Lower Silurian strata, near Cañon City, Colorado, have, according to Messrs. Stanton and Wolcote, been found to contain fish remains, thus placing the first appearance of the great vertebrate kingdom in strata below the Upper Silurian, which is the oldest in which such remains have been recognised in this country. A deep well-boring is being carried on at Wheeling, West Virginia, which was begun in hope of tapping natural gas. This boring is to be carried down as deeply as possible in order to learn something of the character of the rocks at great depths below the earth's surface. A depth of 4,000 feet has been already attained, and the future expense will now be borne by the United States Government. The boring at the Channel Tunnel works has shown the existence of six distinct coal seams, with a total thickness of ten feet of coal. The magnetic survey conducted by Professor Thorpe and Rucker, which revealed the existence of a ridge of paleozoic rocks running from Wales to Selsey Bill, has been extended to France, where by the same method M. Mascart has shown that what is probably the same ridge can be traced from the sea coast near Fécamp in a south-easterly direction through Elboeuf and Rambouillet. Another French geologist, M. G. Rolland, has shown by observations on the Sahara that within comparatively recent times small lakes and watercourses must have

existed over much of the present desert area. This has been confirmed by Fischer, who has discovered numerous examples of recent freshwater mollusca. A somewhat similar phenomenon has been noticed by Mr. G. K. Gilbert, of the United States Geological Survey-the Great Salt Lake in Utah Territory being only a shrunken relic of a far larger freshwater inland sea. Mr. Howarth, M.P., has propounded an ingenious theory to account for the presence of the mammoth in Siberia. Large quantities of the remains of this animal are found, so large as to render it difficult to imagine how such herds could have obtained sufficient food in any climate even partly resembling that of Siberia at the present time. Mr. Howarth argues that the greater mildness of the Siberian climate during the mammoth period must have been due to the then continental character of the Arctic Sea, and to the absence or much lower elevation of the mountain ranges on the South and West. In support of this theory he points out that there is a striking absence of marks of glacial action on the Altai and Ural mountains, and that even in the Himalayas there is little or no evidence that the present glaciers were ever larger, as would have been the case had any great glacial epoch occurred since these hills attained their present elevation. It is interesting to note, in considering this question of glaciation, that Professor Bonney calculates that it would require only a fall of average temperature of 18 degrees to again produce a return of the Ice Age in the British Isles. The discovery of bones of the Saiga antelope, by Dr. J. R. Leeson, in the Thames river gravels at Twickenham is of interest, being the first instance of this species being found in this country. It is of frequent occurrence in the caverns of France and Belgium, but has not previously been known to have had a range so far to the North-West. The difficulty sometimes attaching to the determination of fossil remains is shown by the fact that the Aachenosaurus multidens, a supposed dinosaurian reptile from Aix la Chapelle, has been shown by Dr. A. Hovelacque to be of vegetable origin. The study of earthquakes has now become an important item in the investigation of the secular movements of the earth's crust, and for this the past year has afforded abundant opportunities. One of the most disastrous earthquakes of recent times occurred on October 28 in Japan. The loss of life was estimated at 4,000, while the number of houses, bridges, and permanent works which were destroyed was enormous. The shock was attended by all the marks which usually accompany very severe earthquakes. Over large areas subsidence of the ground to the extent of several feet was noticed. Wide, deep fissures opened at many points, and volcanic eruptions increased in intensity. The shock travelled right round the world, being recorded by the instruments at Berlin and culminating in a sharp reflex shock at Athens two days after the first great shock in Japan. Other serious earthquakes occurred during the year, notably in San Salvador in September, and in Italy in June, and in both cases were preceded and accompanied by an increase of volcanic activity. A large mass of meteoric iron discovered in an extinct volcano crater in Arizona has been found to contain minute black diamonds adhering to the surface of a cavity within the mass. This is the first instance in which actual crystals of diamond have been found in a meteorite, though small quantities of carbon are frequently present.

The work done by the Geological Survey during the past year contains several items of the utmost importance in their bearing on the age of the Paleozoic rocks of the North-west of Scotland. Below the Durness limestone, which is probably of Middle or Upper Cambrian Age, has been noticed a band of Serpulite grit, which has yielded, after careful search, fragments of