raised. By this process about 2,000 tons of carbonate of potash are annually produced from the French distilleries.

It might fairly be supposed that chemistry had now done its utmost to utilise the products of the beet, having obtained from it successively the sugar, the spirit, and the potash. Recent researches, however, have shown that the chemist has by no means exhausted his skill in this direction.

In the residual liquor from the distillation of the molasses there is not only the alkaline matter of the beet-juice, which the root has extracted from the soil, but there is also much organic matter, some of which is nitrogenous. During the calcination of the dried vinasse this organic matter is decomposed, leaving a porous carbonaceous mass associated with the mineral residues. If the concentrated vinasse be subjected to destructive distillation in iron retorts, the volatile products of the decomposition may be secured, just as in the process of gas-making. On passing these products through condensers, the condensable portions will be liquefied while the so-called permanent gases will pass onwards, and may be utilised as fuel. The condensed products consist mainly of tarry and ammoniacal liquors ; and in this respect they resemble the corresponding products obtained in the manufacture of coal-gas, but the chemical composition of the products is not identical in the two cases. Thus the ammoniawater obtained during the distillation of the vinasse-ash contains, among other products, large quantities of the salts of trimethylamine. It is upon their presence that the new manufacture has been established.

6

Trimethylamine, a substance which was discovered nearly thirty years ago by Dr. Hofmann, belongs to the class of organic bodies. known as compound ammonias.' Ammonia is a gaseous compound of nitrogen and hydrogen, which on solution in water forms common 'spirit of hartshorn.' It was shown in 1848, by M. Würtz, an eminent French chemist, that ammonia may have one of its hydrogen-atoms replaced by an organic radical, like methyl. The new body thus formed is called methylamine. Pursuing this course, Dr. Hofmann showed that a second atom of hydrogen might also be replaced by methyl, and thus a body termed dimethylamine was obtained. Finally the same chemist succeeded in replacing the third, or last, atom of hydrogen in ammonia by this radical, and in this way formed trimethylamine. This compound has hitherto been regarded as nothing more than a chemical rarity; but by the new French manufacture to which we are referring, it may now be prepared commercially on an enormous scale.

Although trimethylamine is at present of no industrial value, it is far otherwise with some of its products. Thus, M. Vincent has found that its hydrochlorate may be easily decomposed by heat into free ammonia (which is, of course, a useful product), free trimethylVOL. V.-No. 27. 3 N

amine (which can be again converted into its hydrochlorate), and chloride of methyl. This chloride is a combustible gaseous body, easily condensed to a mobile liquid. Hitherto it has not been obtained in quantity, but M. Vincent can now prepare it to any extent, and, condensing it in strong wrought-iron cylinders, can transport it with ease and safety.

Chloride of methyl may be advantageously used in the preparation of some of the methylated colours, such as Hofmann's violets and the aniline greens. By the newly discovered source of methyl-chloride, the cost of preparation of these colours will be economised, since it can replace the more expensive iodide. But the most interesting application of chloride of methyl which has yet been proposed is that of a refrigerating agent. By the rapid evaporation of the condensed liquid a very great reduction of temperature is produced, and as the liquid is neither poisonous nor corrosive, it promises to become of much importance. Indeed M. Vincent has constructed a freezing machine, in which, by the evaporation of the chloride of methyl, as low a temperature as -55° centigrade may be maintained; a temperature which is considerably below the freezing-point of quicksilver. We have now, therefore, in our hands a new refrigerating agent, by means of which mercury may be frozen by the pound.

In the January number of this Review, we gave an account of Naegeli's researches on the chemistry of yeast, and drew attention to the important discovery, in that fungus, of substances usually supposed to be confined to animals. Since that article was written, a paper has appeared by Mr. Sydney Vines, in which similar results are arrived at for one of the higher flowering plants.

The seeds of many plants contain, in the cells, either of the endosperm or of the cotyledons, grains of a proteinaceous substance, usually wholly or partially soluble in water, and known as aleurone grains. These act as a store of proteid food material, as starch-grains and oil-globules are stores of hydrocarbons. Mr. Vines has made a careful micro-chemical examination of these granules in the blue lupin (Lupinus varius), and has obtained many important results, some new, others confirmatory of the observations of Weyl, a former writer on the same subject.

An extract of the seeds in a solution of common salt was found to contain two proteids belonging to the group of globulins, and hitherto known to occur only in animals; myosin, a constituent of dead muscle; and vitellin, a constituent of the yolk of egg. These two substances-vegetable myosin and vegetable vitellin-were found to have altogether similar reactions to the animal substances of the An aqueous extract of the seeds contained another pro

same name.

• ‘On the Chemical Composition of Aleurone Grains.' Proc. Roy. Soc. vol. xxviii, No. 191, December 19, 1878.

teid, having all the properties of peptone, and agreeing very nearly with the a peptone of Meissner or hemialbumose of Kühne, an easily decomposable peptone formed by the action of gastric or pancreatic juice on proteids.

The above results show how nearly the chemical processes of plants approach to those of animals. The converse is shown, in an even more striking manner, by Mr. P. Geddes's researches on the chlorophyll-containing Planarians.7

diverse groups; it

Chlorophyll occurs in animals belonging to very is found in certain Infusoria, in one of the freshwater sponges, in the common Hydra viridis, and in the sea anemone Anthea cereus, in three species of Planarians, in the tubeworm Chatopterus Valenciennesii, in Bonellia viridis, and in an isopod, Idotea viridis. The fact that the green grains contained in these animals are chlorophyll, as far as their chemical and spectroscopical characters are concerned, has been proved by Cohn, Ray Lankester, and others; but it has never hitherto been certainly shown that they are physiologically identical with plant chlorophyll: that is, that they have the power of decomposing carbonic acid.

Mr. Geddes has now succeeded in proving this point as far as the Planarians are concerned. He found that if a number of specimens were placed in water and exposed to direct sunlight, they gave off bubbles of gas, and that this gas contained from 45 to 55 per cent. of oxygen-enough to rekindle a glowing taper. The habits of the animals are quite such as would be expected from this: they are found on the sand by the sea-shore, exposed to full sunlight, and covered by only a few centimètres of water; in an aquarium they always seek the light, and they were found, in almost every instance, to live far longer if exposed to light than if kept in the dark.

Their chlorophyll was, like that of plants, dissolved out by alcohol; and an examination of the animals thus coagulated and bleached furnished a further link between the physiological processes of these animals and those of plants. Mr. Geddes found that the addition of iodine to an aqueous extract of the alcohol specimens gave the characteristic blue colour, disappearing by heat and reappearing on cooling, which indicates the presence of the distinctively vegetable substance starch.

The starch occurred in the form of minute but definite granules; the chlorophyll, on the other hand, was evenly diffused through the cells, as in many of the lower Algae, not aggregated into grains as in the higher plants.

The significance of these results is well summed up by the author:

" 'Sur la fonction de la chlorophylle avec les Planaires vertes.' Comptes Rendus, December 30, 1878, and Observations on the Physiology and Histology of Convoluta Schultzii. Read before the Royal Society on March 27.

'As the Drosera, Dionaa, &c., which have attracted so much attention of late years, have received the striking name of Carnivorous Plants, these Planarians may not unfairly be called Vegetating Animals, for the one case is the precise reciprocal of the other. Not only does the Dionaa imitate the Carnivorous animal, and the Convoluta the ordinary green plant, but each tends to lose its own normal character. The tiny root and the half-blanched leaves of Pinguicula are paralleled by the absence of a distinct alimentary canal and the abstemious habits of the Planarian.'

The group of Turbellaria, to which the Planarians belong, is one of the lowest among the Metazoa, or many-celled animals, and in many points of structure it forms a starting-point from which a number of the higher groups diverge. In the lowest members of the class, Convoluta and Schizoprora, it has been shown by Metschnikoff, Uljanin, and others, that there is actually no alimentary canal, at any rate in the adult, but that the food taken in at the mouth is passed directly into the general parenchymatous tissue of which the substance of the body is composed, and there digested. The process of alimentation, therefore, in these Turbellaria, resembles, in its general features, that met with in Infusoria.

That the actual details of the process are similar in the two cases has recently been made out by Metschnikoff's researches on two genera of Turbellarians, Mesostomum and Planaria. The main difference between the process of ingestion of nutriment in a Protozoon and in one of the higher animals is that, in the latter, the food is brought into a state of solution, while in the digestive cavity, by means of certain juices secreted by the cells lining its walls, and is then absorbed by those cells, by a passive process of diffusion, while in the Protozoon the food particles are taken bodily into the substance of the one-celled organism and there assimilated.

In giving an account, in a former number of this Review,' of Reichenbach's researches on the development of the crayfish, we called attention to that author's interesting observation that the cells of the developing embryo engulf the yolk-spheres which serve them as pabulum by surrounding them with pseudopodia, the cells of the embryo crustacean thus behaving like so many independent Amabæ. The individual cells, or sponge-particles, of the many-celled sponges take in their nutriment in the same active manner; but it is quite a surprise to find the comparatively complicated Turbellaria in a similar case.

One of the species examined by Metschnikoff, Mesostomum Ehrenbergii, feeds largely on the freshwater worm Nais. When

Ueber die Verdauungsorgane einiger Süsswasser-Turbellarien.' Zoologischer Anzeiger, December 30, 1878.

9 Nineteenth Century, December 1877.

observed about an hour after a meal, the cavity of the alimentary canal contained nothing but the cuticle of the worm and its setæ, but in the interior of the amoeboid cells lining the canal were found the whole of its soft parts, certain characteristic pigmented cells being especially noticeable. Sometimes even the sets and fragments of other hard parts were found to have been taken in by the alimentary cells. The case was rendered even more striking by feeding the worms on carmine before allowing them to be devoured by the Mesostomum. In this case the digestive cells of the latter were seen, after an interval, to be crammed with particles of the colouring matter.

Similar experiments were tried with Planaria lactea and P. polychroa, which were fed upon blood containing finely divided carmine or indigo. In this case the cavity of the alimentary canal completely vanished during digestion, its lining cells swelling up considerably beyond their original size, and being filled with immense numbers of blood-corpuscles and granules of colouring matter.

Within the last few years the attention of many accomplished histologists has been directed to the difficult problem of determining the exact structure of the nuclei of cells, a subject of which next to nothing was known up to the commencement of the present decade. In Professor Stricker's article 'On the General Character of Cells,' published in 1869,10 the question is discussed as to whether the nucleus is vesicular or not, and it is stated that in cell-division the nucleus ' elongates, becomes hourglass-shaped, and ultimately constricted into two segments;' but nothing is said as to its minute structure beyond the fact of the presence of one or more nucleoli.

Recently, however, the question of the exact structure of nuclei, and of the precise part played by them in cell-division, has been taken up by Auerbach, Strasburger, Van Beneden, and Oscar Hertwig, of whose researches an account was written about three years since by Mr. Priestley," as well as by Klein, Flemming, and many others. Their observations seem to show that the cell-nucleus-the length of which, it must be remembered, does not average more than 20 of an inch-is enclosed in a definite membrane, and consists of a more or less complicated network of delicate protoplasmic filaments, the intra-nuclear network, embedded in a pale, apparently structureless ground substance. According to Dr. Klein,12 this network is continuous through minute apertures at the poles of the nuclear membrane, with an intra-cellular network in the substance of the cell itself,

10 Stricker's Human and Comparative Histology, vol. i. English translation by H. Power, 1870.

11 Recent Researches on the Nuclei of Animal and Vegetable Cells, and especially of Ova.' Quart. Journ. of Microscopical Science, vol. xvi. p. 131. 1876.

13 Observations on the Structure of Cells and Nuclei.' Quart. Journ. of Microscopical Science, July 1878, and April 1879.