starting-point for similar monographs of other divisions of the fossil plants of America.

Professor Lesquereux gives an account of the circumstances under which this formation was discovered and explored by Dr. Hayden and others, and then considers the surface and stratigraphical distribution of the species. In accordance with Dr. Hayden's views, the author finds the group to be of marine origin, as shown by the occurrence of various species of marine mollusks.

Numerous important general considerations are presented by Professor Lesquereux in connection with his subject, and in the concluding part of the memoir he remarks that he is not prepared to commit himself in regard to the correlation of the flora of the Dakota group with that of subsequent geological epochs, and their identity, preferring to wait the gathering and examination of other series. He, however, states that this flora, without affinity with any preceding vegetable types, without relation to the flora of the lower tertiary of the United States, and with scarcely any forms. referable to species known from coeval formations in Europe, presents, as a whole, a remarkable and, as yet, unexplained case of isolation.

ABSORPTION OF OXYGEN BY PLANTS IN THE DARK.

According to Dehérain, leaves kept in a confined atmosphere, in darkness, will absorb the whole of the oxygen, and still continue to give off carbonic acid, the resistance to asphyxia varying with the species. The rapidity of growth and energy of respiration of plants are both favored by obscure heat; and it is shown that the internal combustion, by the absorption of oxygen and emission of carbonic acid, is the origin of part of the heat necessary to the elaboration of new proximate principles in the plant.-21 A, Sept., 1874, 910.

TRANSFER OF THE ALBUMINOIDS OF THE SEED INTO THE

PLANTLET.

It is a familiar fact that germinating plants derive their nutrition from the reserve materials in the cotyledon, and that the insoluble starch of the latter is converted, in the process of germination, into soluble sugar, and, as such, transferred to the new plantlet. Some late German investigations

have thrown light upon the method of transfer of the albuminoids of the seed into the different parts of the new plant during the process of germination. Asparagin, first discovered in asparagus, seems in general to perform this task, in giving up, in the first place, in the respiration of the plant, a certain amount of carbonic acid and water, and is afterward united in the new plant to corresponding amounts of carbon and hydrogen, to form albuminoid materials again.

EFFECT OF CHLOROFORM ON VEGETABLE INFUSIONS. Barnes has made a communication to the Pharmaceutical Society of Great Britain upon the preservative effect of chloroform on vegetable infusions, in which he shows that of all substances applicable to the purpose of preparing unchanged infusions for medical purposes chloroform is among the most valuable. In one case four grammes of chloroform were added to four fluid ounces of mucilage of tragacanth, and at the expiration of a month the mass was found to be perfectly neutral, while another portion, not treated with the chloroform, had become strongly acid and unfit for use.

It is equally serviceable in preventing the souring of paste and gum-arabic, its special property seeming to depend upon the power possessed by chloroform to prevent alcoholic fermentation. When mixed with yeast, even in a warm place, fermentation and the accompanying development of alcohol is prevented.

Barnes also found that by adding twenty minims of chloroform to eight fluid ounces of fresh milk, the milk remained fresh after the lapse of five days, though kept in a warm place. If the milk thus treated be boiled just before using, all the chloroform will be driven off. The same application has also been used in the preservation of concentrated infusions of quassia, colombo, gentian, etc.-14 A, March 5, 1875, 441.

EFFECT OF SOLUTIONS ON A GROWING VINE.

Baudrimont has been continuing his experiments on the influence upon the branches of a growing vine of immersion in water containing various substances in solution, and has obtained some rather remarkable results, by various poisonous agencies, some appearing actually to increase the vigor

of growth of the vine and prolong its existence, as in the case of chloride of potassium; while others cause the plant to wither, as in creosote and carbolic acid. Bromide and iodide of potassium seem to act in the same manner as chloride of potassium. Chloral hydrate exercises a very poisonous influence, destroying the branch vine in three days, the effect differing from that of carbolic acid. One of the most curious phenomena is that which is exhibited in the fall of the leaves. In some instances the petiole becomes detached at the point where it is inserted in the branch. This takes place with such substances as bi-chloride of mercury, and chloride, bromide, and iodide of potassium. In other cases it is the limb which separates from the extremity of the petiole. This occurs with ordinary water, and the nitrates of ammonia, potash, and soda. In one single instance both forms of observation have been observed under the influence of the same substance. Sometimes, again, the branch dies while the leaves continue to adhere to it. This is the case after the use of hydrocyanic acid and the essence of turpentine. Chloride of potassium acts as an invigorating and preserving agent, quite exceptional in its character. A current of ammonia allows the branch to preserve its freshness for eight days, after which it withers.-1 B, Dec. 20, 1874, 189.

HEAT AND VEGETATION.

In some remarks on the relation between heat and vegetation, which are translated by Firket from the work of Kabsch on the "Vegetation of the Earth," the latter states that the three fundamental laws of vegetation are as follows: First, for each plant there exists a maximum and a minimum temperature, between which this species is capa ble of normally exercising its vital functions; second, in the germination of grains, the opening of buds, the maturing of fruit, each has need of a certain average degree of temperature, which may be very different according to the species of plant; third, each species of vegetable, in order to go. through the various phases of its existence, needs a certain sum total of heat, and it is only in the localities where this sum total is furnished every year, and where the conditions of humidity and the constitution of the soil are equally favorable, that the existence of the plant can be regarded as

assured. Applying these principles to certain well-known plants, Kabsch finds for the grape-vine, for instance, that the limiting temperatures between which the vine can be cultivated naturally are minus 19° C. and plus 20° C. The aver age degree of temperature must be plus 8° C.; the sum total throughout the year must be 2900°.- La Chaleur, Ghent, 1873, 46.

HEAT AND VEGETATION.

Morren, of Liege, has presented his views on the relation of heat to vegetation, especially as to the dynamic influence of heat on the growth of plants. He says that we will elucidate this matter slowly, in proportion as physics and chemistry make progress in the revelation of the nature of bodies and forces. Heat has an influence upon the growth of plants, on the circulation of the sap, elaboration of the cells, the respiration, and many other phenomena. The relation of heat to the development of plants, and particularly the periodic phases of vegetation, are phenomena known through the epoch at which they manifest themselves, the mean dates of these manifestations, and the average deviations therefrom.

After giving an abstract of the results of the labors of Schubeler, Hofmann, Fritsch, Linnsser, and Kabsch, Professor Morren states that a problem of high importance, and one which has been, perhaps, too much neglected, is that of the relation between heat and the weight acquired by the plant under the action of the solar rays, and especially its relations to the quantity of carbon fixed in the organic matter, as far as we can at present estimate that. In a temper

ate climate a hectare of forest and prairie, or cultivated land, fixes in one year from 1500 to 6000 kilogrammes of carbon; and in order to accomplish this work vegetable organisms utilize between one and four thousandths of the heat which has been received by solar radiation upon the surface that they occupied. It is evident that such phenomena as take place periodically, viz., germination, leafing, etc., are acts of growth; such growth supposes movement; the fact of the movement necessitates consumption of force, which consumption is but a transformation of heat. If, to fix our ideas, we suppose an apple to fall from a tree, we have but to reflect upon the laws of force in order to see that the apple must

have been previously carried up into the tree, for it evidently has not raised itself there. It is the power of the heat proceeding from the sun which has effected the development and growth of the tree. It is, therefore, practicable to determine the mechanical coefficient of growth, as Sausom has determined the mechanical coefficient of nourishment for foods. It is the property of vegetable organisms to utilize the heat received by them from any source, for the conversion of crude material into such forms as are needed by them for their own growth. In this process, however, force is neither created nor lost, although much of it is secreted within the body of the plant or mineral. Other things being equal, the quantity of carbon fixed in any plant varies with the average elevation of the height of its centre of gravity. Morren, on the Energy of Vegetation, Brussels,

1873.

THE RESPIRATION OF LEAVES IN THE DARK.

An important paper by Dehérain and Moissan upon the respiration of leaves in the dark has lately been published in Comptes Rendus. Among the more important conclusions reached by the authors in their researches are: First, that the quantity of carbonic acid which is thrown off by leaves in the dark increases with the increase of temperature; second, that the quantity of carbonic acid thrown off is comparable to that yielded by the cold-blooded animals; third, that leaves kept in the dark absorb more oxygen than they throw off carbonic acid; fourth, that leaves continue to throw out carbonic acid in an atmosphere deprived of oxygen.

The authors present the following hypothesis upon the physiological uses of this internal combustion which takes place in the leaves, as the result of their numerous experiments. The immediate constituents which are necessary to the growth of the plants, and to the formation of new organs, are in part formed in the leaves. This growth is especially favored by warmth in the dark, as a principle well known to gardeners who cover plants, the development of which they wish to accelerate, under glass, in which case a part of the light necessary for the composition of the carbonic acid is reflected, but an elevated temperature is se