this colouration to the effect of sulphur, which should be so generally spread about in the shape of some sulphate as to produce this colouration. The author, though abstaining from stating any precise cause at all, inclines to the belief that the cooling effect of the cold body held in the flame has something to do with this phenomenon. Perfectly pure hydrogen, burning from a platinum burner, as well as from iron or glass burners, exhibited the phenomenon, when cold bodies, just after having been cleaned by scraping or filing, were held in that flame.

According to M. Baille the moon's surface emits as much heat as a cube filled with water, covered with lamp-black, having a surface of 6 5 square centims., and placed at a distance of 35 metres from the thermo-electric measuring apparatus employed by the author for his experiments.

In a paper "On the Reflexion of Heat on the Surface of Fluor Spar and other Substances," by M. Magnus, we learn that the following substances reflect at an angle of 45° the undermentioned quantities of heat:-silver, between 83 and 90 per cent.; glass, between 6 and 14 per cent.; rock-salt, between 5 and 12 per cent.; fluor spar, between 6 and 10 per cent. The same author finds that different bodies heated to 150° emit different kinds of heat; some substances only emit one kind of heat, others, again, various kinds. Pure rock-salt is mono-thermic, sylvine (chloride of potassium) behaves in a similar manner.

M. Delaurier proposes for concentrating and utilizing the sun's rays, a truncated cone, open at both ends and lined inside with polished silver, the sun's rays being admitted by the largest opening. Since the angle of reflexion is equal to the angle of incidence, all direct or reflected rays will be united at the narrower end of the cone. It is clear that the greater the length of the cone, the greater will be the concentration of heat. The author enters into a discussion on the advantage of this contrivance over the use of lenses and mirrors, and he very enthusiastically surmises that the heat of the sun's rays may be so concentrated as to serve for various purposes instead of the combustion of fuel, especially in countries where, as in Algeria, the heat and splendour of the sun are more permanently felt than it is in our climate.

ELECTRICITY. Our limited space prevents us from doing more than allude to one or two novelties in this science. Dr. Runspaden has published a monograph on a subject first observed by Professor Wöhler, that when water acidified with sulphuric acid is decomposed by a galvanic current, and silver is used as electrodes, peroxide of silver is deposited on the anode, and metallic silver on the cathode. The two main questions answered by the author by a series of

experiments are, What is the cause of the formation of peroxide of silver on the positive pole, and by what means does the metallic silver find its way from the positive to the negative pole? In an appendix, the author informs us that there is an error in all works on physics, viz. the statement that gold (pure, of course) and platinum are the only two metals which are not oxidized at the positive pole, when serving as electrodes. The author finds, and has confirmed by experiments carefully conducted, so as to exclude any source of error, that gold itself is oxidized to a very considerable extent, and that during such experiments as those alluded to, there is formed a definite oxide,-Au, O, 3H,0; containing gold, 79 47 per cent.; oxygen, 9 62 per cent.; water, 10 91 per cent.

A mode has been devised for depositing copper, silver, or gold by the electric process upon paper or any other fibrous material. This is accomplished by first rendering the paper a good conductor of electricity, without coating it with any material which will peel off. One of the best methods is to take a solution of nitrate of silver, pour in liquid ammonia till the precipitate formed at first is entirely dissolved again; then place the paper, silk, or muslin, for one or two hours in this solution. After taking it out and drying well, it is exposed to a current of hydrogen gas, by which operation the silver is reduced to a metallic state, and the material becomes so good a conductor of electricity, that it may be electro-plated with copper, silver, or gold in the usual manner. Material prepared in this manner may be employed for various useful and ornamental purposes.

12. ZOOLOGY-ANIMAL PHYSIOLOGY AND

MORPHOLOGY.

PHYSIOLOGY.

The Origin of the Fibrin of the Blood.-Dr. Heynsius in the course of a series of investigations on the albuminoids of the blood, endeavoured to determine whether any of the constituents of the blood corpuscle contribute to the formation of fibrin. He finds that the quantity of fibrin obtained from the same blood by the same treatment is somewhat variable, owing to the defectiveness of the method. By whipping the blood, a greater amount of fibrin is obtained than by washing the clot. The addition of phosphate of soda to the blood previous to coagulation, causes great difference in the amount of fibrin. In the plasma of the dog, the quantity of fibrin, or of its parent substances (as taught by Buchanan and Schmidt), is certainly smaller than the quantity of fibrinogenetic

In chicken's blood

substance and globulin contained in the blood. the quantity of fibrin obtained is alone much greater than the quantity of fibrinogenetic substance that can be separated from the plasma diluted with a solution of salt of four per cent. Hence it

is not possible to doubt that the albuminoid substance of the socalled stroma of the blood corpuscles contributes to the formation of fibrin. These observations of Dr. Heynsius are of very great value, as they tend further to explain the mysterious process of coagulation of the blood, for although the ammonia theory is abandoned, and Schmidt's view of a fibrinogenetic material in the plasma, and a fibrinoplastic one in the corpuscles, has been taught as the best explanation which could be offered of the phenomenon, yet further details were and are still wanting. It appears now that the corpuscles can furnish fibrinogenetic as well as fibrinoplastic substance.

Whence comes the free Hydrochloric Acid in the Stomach?— Acid phosphates reacting on alkaline chlorides produce free hydrochloric acid. In the capillaries of the stomach, distended by engorgement, acid phosphates are believed by Professor Horsford, of Cambridge, Mass., to be formed, and thus the free hydrochloric acid produced. By dialytic action the hydrochloric acid is rapidly separated from the inner tissue where it is formed, and coming in contact with the epithelial cells of the gastric tubules, bursts and dissolves some of them, thus forming pepsine, which, together with the acid, some phosphates and chlorides, escapes into the stomach to act in the liquefaction of food.

Development of Gas in Protoplasm.-Dr. Th. Engelmann has observed in Arcella, a minute protozoon like an Amoeba with a shell, a periodical development of gas. Dr. Engelmann made his observations on specimens confined in a gas chamber, and describes minutely how gradually in the protoplasmic hyaline substance of the animalcule, black points arise, which as gradually coalesce, forming a distinct air-bubble. This gas can after a time be absorbed again, and reasons are given for believing that a sort of volition is exercised by the Arcella in the secretion and absorption of the gas which they use in the manner of a float or air-bladder. The airbubbles are not connected with the contractile vacuoles or with the nuclei. The air-bubbles, it is important to observe, do not occur in the non-granular protoplasm of the pseudopodia, but in the granular substance, and are not spherical but of an irregular form, which, as Dr. Engelmann observes, proves that the protoplasm is not in the condition of aggregation of a fluid. The chemical composition of the gas thus so remarkably developed by the Arcella was not determined, nor the mechanism (if any exist) of the formation and disappearance of the air-bubbles. The discovery is of importance from two points of view: in the first place, for the development of

gas in protoplasm as a physiological phenomenon; in the second place, for the supposed voluntary nature of this development, of which this exceedingly simple organism makes use for the purpose of locomotion. In the Cambridge Journal of Anatomy' this paper is noticed very fully by Dr. Moore.

Starch in Muscles.-Nasse has found starch in the muscles, of which he considers it a normal constituent, and believes it to be consumed in muscular action, forming a part of the fuel with which our muscular engines are fed. It is not many years since starch was regarded as a peculiarly vegetable product, and even now it seems difficult to persuade some people that it is not. Bernard's discovery of glycogen, or liver-starch, is, however, sufficiently well known, and so-called "annyloid substance" has been found in many other organs. The starch in muscle is probably connected with the sugar there found, and some time since shown to be connected with muscular activity by Ranke.

The Endings of Nerves in the Liver.-Professor Pflüger, of Bonn, continues his valuable researches on the terminations of nerves in the various glands of the body. By the use of hyperosmic acid applied in a method peculiar to himself, Pflüger has shown that the nerves to the salivary and pancreatic glands end in or as parts of the substance of the secreting cells of those glands. He now shows, in the last number of his Archiv,' that this method of termination is found also in the liver. His observations on the structure of the liver generally are confirmatory of Dr. Beale's views, in opposition to some recent German investigators. He speaks of the hepatic cell as a nucleated swelling of the axis cylinder of a nerve. Hence the influence of the nervous system on the secretion of bile, as seen in the well-known influence of mental affections upon it, is rendered intelligible. So, too, with regard to other glands, for Pflüger holds that it is impossible to understand the action of a nerve upon a secreting gland, or upon any other active structure, without the supposition of a continuity of structure between the two, and this continuity he has now demonstrated in the more important glands.

The Secretory Nerve of the Parotid Gland.-Professor Eckhard has, in a recently published essay, given an account of a series of careful researches on the nerves which directly stimulate the secretion of the parotid gland. By various arguments he is led finally to the conclusion, that in dogs the secretory nerve of the parotid is the tympanic branch of the glosso-pharyngeal nerve.

MORPHOLOGY.

Cuckoo's Eggs.-Professor Alfred Newton, of Cambridge, in a recent number of Nature' advocates and endeavours to explain Baldamus' views with regard to the eggs of the cuckoo. Baldamus maintained that the popular assertion (popular where ?) that the cuckoo lays an egg which varies somewhat in colour according to the nest in which it is deposited,-being modified according to the case, so as to imitate the appearance of the eggs belonging to the nest is right. This, Professor Newton accepts as a fact, having seen Dr. Baldamus' specimens, and he endeavours to explain this modification of the egg which must otherwise be supposed to be a voluntary act of the bird, by an appeal to the Darwinian theory.

Professor Newton supposes that of a number of eggs laid by cuckoos in the nests of a given species of bird, those eggs would be most likely to come to maturity which, cæteris paribus, had the strongest resemblance to the egg of the given species. He further supposes that the offspring would inherit a tendency to lay in the nest of the same species which its parent had imposed upon, and thus there would be established a race of cuckoos infesting the nest of species A, another race infesting B, and so on, each of which races must tend to imitate closely more and more the eggs of the infested species. Mr. Sterland objects to this, that in England no such variety in cuckoos' eggs as that described by Baldamus is seen, and that the hedge-sparrow's blue eggs are those most commonly associated with the utterly different speckled eggs of the cuckoo. He also maintains that the supposed separate races of cuckoo would not be able to keep unmixed, that they must get interbred, but he forgets that the females could only be crossed by males, who may be unable to transmit or affect peculiarities belonging to the females who were their progenitors or happen to be their consorts.

The Kinship of the Vertebrates and the Ascidian Molluscs.Kowalevsky, a Russian observer, has made some investigations into the development of Ascidians, which are likely to excite more attention than anything of the kind has for years past. His observations were made two years ago, and were noticed as of importance, first by Ernst Haeckel, of Jena, Darwin's great champion and exponent in Germany. Now Professor Kupffer, of Kiel, confirms Kowalevsky's statements, and more credence and attention will be daily given to them. It has been long known that the larvæ of certain Ascidians, when minute free-swimming creatures, have somewhat the aspect of tadpoles, having like them a long swimming tail. This tail has a firm gelatinous rod running along it and projecting into the body of the larva. Now in all vertebrates one of the earliest structures elaborated in the course of development is a long