process of germination is by no means a simple one. The nutriment stored up in the seed is in great part in the condition of insoluble starch; and this must be brought into a soluble form before it can be appropriated by the embryo. The metamorphosis is effected by the agency of a ferment termed diastase; which is laid up in the immediate neighbourhood of the embryo, and which, when brought to act on starch, converts it in the first instance into soluble dextrine, and

then (if its action be continued) into sugar. The dextrine and sugar,

combined with the albuminous and oily compounds also stored up in the seed, form the "protoplasm" which is the substance immediately supplied to the young plant as the material of its tissues; and the conversion of this protoplasm into various forms of organized tissue, which become more and more differentiated as development advances, is obviously referable to the vital activity of the germ. Now it can be very easily shown experimentally that the rate of growth in the germinating embryo is so closely related (within certain limits) to the amount of Heat supplied, as to place its dependence on that agency beyond reasonable question; so that we seem fully entitled to say that Heat, acting through the germ, supplies the constructive force or power by which the Vegetable fabric is built up. But there appears to be another source of that power in the seed itself. In the conversion of the insoluble starch of the seed into sugar, and probably also in a further metamorphosis of a part of that sugar, a large quantity of carbon is eliminated from the seed by combining with the oxygen of the air so as to form carbonic acid; this combination is necessarily attended with a disengagement of heat, which becomes very sensible when (as in malting) a large number of germinating seeds are aggregated together; and it cannot but be regarded as probable that the heat thus evolved within the seed concurs with that derived from without, in supplying to the germ the force that promotes its evolution.

*

The condition of the Plant which has attained a more advanced stage of its development differs from that of the germinating embryo essentially in this particular, that the organic compounds which it requires as the materials of the extension of the fabric are formed by itself, instead of being supplied to it from without. The tissues of the coloured surfaces of the leaves and stems, when acted on by light, have the peculiar power of generating at the expense of carbonic acid, water, and ammonia-various ternary and quaternary organic compounds, such as chlorophyll, starch, oil, and albumen; and of the compounds thus generated, some are appropriated by the constructive force of the Plant (derived from the heat with which it is supplied) to the formation of new tissues; whilst others are stored up in the cavities of those tissues, where they ultimately serve either for the evolution

* The effect of Heat is doubtless manifested very differently by different seeds; such variations being partly specific, partly individual. But these are no greater than we see in the inorganic world; the increment of temperature and the augmentation of bulk exhibited by different substances when subjected to the same absolute measure of heat, being as diverse as the substances themselves. The whole process of "malting," it may be remarked, is based on the regularity with which the seeds of a particular species may be at any time forced to a definite rate of germination by a definite increment of temperature.

of parts subsequently developed, or for the nutrition of animals which employ them as food. Of the source of those peculiar affinities by which the components of the starch, albumen, &c., are brought together, we have no right to speak confidently; but looking to the fact that these compounds are not produced in any case by the direct union of their elements, and that a decomposition of binary compounds seems to be a necessary antecedent of their formation, it is scarcely improbable that, as suggested by Prof. Le Conte (op. cit.), that source is to be found in the chemical forces set free in the preliminary act of decomposition, in which the elements would be liberated in that " nascent condition" which is well known to be one of peculiar

energy.

The influence of Light, then, upon the Vegetable organism appears to be essentially exerted in bringing about what may be considered a higher mode of chemical combination between oxygen, hydrogen, and carbon, with the addition of nitrogen in certain cases; and there is no evidence that it extends beyond this. That the appropriation of the materials thus prepared, and their conversion into organized tissue in the operations of growth and development, are dependent on the agency of Heat, is just as evident in the stage of maturity as in that of germination. And there is reason to believe, further, that an additional source of organizing force is to be found in the retrograde metamorphosis of organic compounds that goes on during the whole life of the plant; of which metamorphosis the expression is furnished by the production of carbonic acid. This is peculiarly remarkable in the case of the Fungi, which, being incapable of forming new compounds under the influence of light, are entirely supported by the organic matters they absorb, and which in this respect correspond on the one hand with the germinating embryo, and on the other with Animals. Such a decomposition of a portion of the absorbed material is the only conceivable source of the large quantity of carbonic acid they are constantly giving out; and it would not seem unlikely that the force supplied by this retrograde metamorphosis of the superfluous components of their food, which fall down (so to speak) from the elevated plane of "proximate principles" to the lower level of comparatively simple binary compounds, supplies a force which raises another portion to the rank of living tissue; thus accounting in some degree for the very rapid growth for which this tribe of Plants is so remarkable. This exhalation of carbonic acid, however, is not peculiar to Fungi and germinating embryos; for it takes place during the whole life of Flowering Plants, both by day and by night, in sunshine and in shade, and from their green as well as from their dark surfaces; and it is not improbable that, as in the case of the Fungi, its source lies partly in the organic matters absorbed; recent investigations* having rendered it probable that Plants really take up and assimilate soluble humus, which, being a more highly carbonized substance than starch, dextrine, or cellulose, can only be converted into compounds of the latter kind by parting with some of its carbon. But it may also take * See the Memoir of M. Risler, "On the Absorption of Humus," in the 'Bibliothèque Universelle,' N. S. 1858, tom. i. p. 305.

place at the expense of compounds previously generated by the plant itself, and stored up in its tissues; of which we seem to have an example in the unusual production of carbonic acid which takes place at the period of flowering, especially in such plants as have a fleshy disk or receptacle containing a large quantity of starch; and thus, it may be surmised, an extra supply of force is provided for the maturation of those generative products, whose preparation seems to be the highest expression of the vital power of the Vegetable organism.

The entire aggregate of organic compounds contained in the vegetable tissues, then, may be considered as the expression not merely of a certain amount of the material elements, oxygen, hydrogen, carbon, and nitrogen derived (directly or indirectly) from the water, carbonic acid, and ammonia of the atmosphere, but also of a certain amount of force which has been exerted, in raising these from the lower plane of simple binary compounds to the higher level of complex "proximate principles;" whilst the portion of these actually converted into organized tissue may be considered as the expression of a further measure of force, which, acting under the directive agency of the germ, has served to build up the fabric in its characteristic type. This constructive action goes on during the whole Life of the Plant, which essentially manifests itself either in the extension of the original fabric (to which in many instances there seems no determinate limit), or in the production of the germs of new and independent organisms. -It is interesting to remark that the development of the more permanent parts involves the successional decay and renewal of parts whose existence is temporary. The "fall of the leaf" is the effect, not the cause, of the cessation of that peculiar functional activity of its tissues, which consists in the elaboration of the nutritive material required for the production of wood. And it would seem as if the duration of their existence stands in an inverse ratio to the energy of their action; the leaves of "evergreens," which are not cast off until the appearance of a new succession, effecting their functional changes at a much less rapid rate than do those of "deciduous" trees, whose term of life is far more brief.

Thus the final cause or purpose of the whole Vital Activity of the Plant, so far as the individual is concerned, is to produce an indefinite extension of the dense, woody, almost inert, but permanent portions of the fabric, by the successional development, decay, and renewal of the soft, active, and transitory cellular parenchyma; and, according to the principles already stated, the descent of a portion of the materials of the latter to the condition of binary compounds, which is manifested in the largely increased exhalation of carbonic acid that takes place from the leaves in the later part of the season, comes to the aid of external Heat in supplying the force by which another portion of those materials is raised to the condition of organized tissue. -The vital activity of the Plant, however, is further manifested in the provision made for the propagation of its race by the production of the germs of new individuals; and here, again, we observe that whilst a higher temperature is usually required for the development of the flower, and the maturation of the seed, than that which suffices to sus

tain the ordinary processes of vegetation, a special provision appears to be made in some instances for the evolution of force in the sexual apparatus itself, by the retrograde metamorphosis of a portion of the organic compounds prepared by the previous nutritive operations. This seems the nearest approach presented in the Vegetable organism, to what we shall find to be an ordinary mode of activity in the Animal. That the performance of the generative act involves an extraordinary expenditure of vital force, appears from this remarkable fact, that blossoms which wither and die as soon as the ovules have been fertilized, may be kept fresh for a long period if fertilization be prevented.

The decay which is continually going on during the life of a Plant restores to the Inorganic world, in the form of carbonic acid, water, and ammonia, a part of the materials drawn from it in the act of vegetation; and a reservation being made of those Vegetable products which are consumed as food by Animals, or which are preserved (like timber, flax, cotton, &c.) in a state of permanence, the various forms of decomposition which take place after death complete that restoration. But in returning, however slowly, to the condition of water, carbonic acid, ammonia, &c., the constituents of Plants give forth an amount of Heat equivalent to that which they would generate by the process of ordinary combustion; and thus they restore to the inorganic world not only the materials but the forces, at the expense of which the Vegetable fabric was constructed. It is for the most part only in the humblest Plants, and in a particular phase of their lives, that such a restoration takes place in the form of motion; this motion being, like growth and development, an expression of the vital activity of the "zoospores " of Algae, and being obviously intended for their dispersion.

Hence we seem justified in affirming that the Correlation between Heat and the Organizing force of Plants is not less intimate than that which exists between Heat and Motion. The special attribute of the Vegetable germ is its power of utilizing after its own particular fashion the Heat which it receives, and of applying it as a constructive power to the building-up of its fabric after its characteristic type.

THE REPUTED FOSSIL MAN OF THE NEANDERTHAL.

By Professor WILLIAM KING, Queen's University in Ireland, and Queen's College, Galway.

As it is my intention to confine myself to the consideration of the Neanderthal fossil with reference to its place in Nature, I must necessarily be brief in my remarks on the circumstances under which it occurred, and on its geological age.

The fossil was found in 1857, embedded in mud in a cave or fissure intersecting the southern rocky side of the ravine or deep narrow valley, called the Neanderthal, situated near Hochdal between Düsseldorf and Elberfeld. A small stream or rivulet, known as the Düssel, flows along a narrow channel about sixty feet below the lowest part of the fissure, and on one side of the valley.

It has long been known that human bones, belonging to an extinct race, and occurring in stalagmite along with the remains of the mammoth and other fossil animals, have been found in the limestone fissures or caverns of the lofty precipices which overhang the river Meuse, in Belgium, about seventy English miles south-west of the Neanderthal.

Lyell's late work, The Antiquity of Man,' contains a very lucid description of the Meuse caverns, and of the one under consideration. In both cases it is evident that we have examples of ancient swallowholes, into which have been washed bones, mud, and gravel, when their openings existed in the bed of large and powerful rivers. It was doubtless by the incessant abrading action of such ancient streams, continued for countless ages, that the Neanderthal, and much of the broad valley of the Meuse, became scooped out.

Few Geologists will dispute that the Meuse caverns are of the same age as the flint-implement gravels of the Somme, and that both belong to the latest division of the glacial or (as I have lately termed it) Clydian period.* If we accept the physical conditions of the Meuse caverns as demonstrative of their having been filled up in that remote age, we cannot but recognize in the corresponding conditions of the Neanderthal fissure evidences which claim for it an equally high antiquity, notwithstanding certain differences seemingly supporting the opposite conclusion.

The want of stalagmite and the doubtful absence of remains of extinct animals in the Neanderthal fissure may be readily explained; and as to the physical differences, the Düssel is certainly not to be compared with the Meuse for size and abrading power, but it must be admitted that a mere rivulet may take quite as much time to scoop out a "ravine" as a river to excavate a considerable portion of a broad valley.

Having finished my preliminary remarks, I shall next proceed to notice the fossil itself.

According to Dr. Fuhlrott, of Elberfeld, the skeleton was found

* See 'Synoptical Table of the Aqueous Rock-Systems,' 5th edition.