GERMINATION. The physical changes dur ing the germination of seeds has long been a careful study by students of vegetable physiology. In the germination of seeds heat, moisture, and air are requisite. As each species of plants have their zero at which they are killed, so each has its temperature at which it germinates most kindly. Thus the glacier produces a so-called red snow, from minute species of algae, which grow at far below the freezing point, and are killed when the temperature is raised to the melting point of snow. To plants flowering in extreme cold succeed vegetation flowering almost as soon as the frost is out of the ground. Next come hardy plants that endure the frosts of our severest winters, and start into life with the first warm days of spring. Half hardy plants follow still later, and tender plants do not begin to grow until all danger of frost is over, to be again cut clown with the first frosts of autumn. The pea requires forty to fifty degrees of sun heat for its vegetation; corn, fifty to sixty degrees, and cucumbers sixty to seventy degrees as the lowest heat at which they germinate. The range for plants, hardy and tender, being from about 34° to 140° as the lowest germinating heat, and the highest degree of sun, they will bear. Added to this, moisture at the roots must always be present. Indeed, many plants can not exist in a dry atmosphere at all. Some plants, as many northern ferns, require a moist, cool heat, and also shade, while tropical ferns, as well as many other tropical plants, require not only a high heat, but an atmosphere constantly saturated with moisture, or nearly so. And most of them require a strong heat, hence the necessity of artificial houses for their propagation and care, in the temperate zone. In the article Botany, the germination of the acorn is illustrated. The two lobes of the fruit do not perform the office of leaves as in the bean, but nevertheless serve to nourish the young plant. Above we illustrate, Fig. 1, the growth of the young maple. Here the two cotyledons escape from the shell, change color and become the first pair of leaves, of the plant, or seed leaves as they are called. The radicle, in its first growth, sends out the root, which pierces the soil, and the plumule (the bud above the leaves), puts forth true leaves. Fig. 2 shows the process of growth, the young rootlets, feeding from the soil, and the true leaves elaborating the sap furnished. It is now a true and independent plant, which in process of time will, if no disaster happens to it, form one of the monarchs of the forest. Fig. 3 shows the seed of wheat in the process of ger mination. Here the seed remains in the earth and,by its change and decay, nourishes the plant until its roots can draw nourishment from the soil. The starch of the grain (a) is chemically changed to this end as in other seeds, and as in all the grasses, the radicle strikes root, and the spire rises, inde pendently of the seed, above ground to elaborate the juices sent up by the root. Prof. Poey, in an article on Meteorology asApplied to Agriculture, some time since collected a mass of information from the most eminent investigators, at home and abroad.
From this we condense the following inter esting data in relation to the vital forces of plants: From the highest antiquity innumerable theories have been proposed explaining the vitality which precedes the development of the germ, the repro duction and organization of living beings,animal and vegetable. That action has been successfully attributed to an entity, a principle, an agent, or a force, acting on organic matter exteriorly or interiorly, or in both cases at the same time. Prof. Joseph Henry, deceased, and during his life secretary of the Smithsonian Institution, thought that vitality is a directing principle and not a mechanical power, the expenditure of which does work. This principle, as an engi neer, directs the power which is given out when a part of the oxygenized molecules runs down into inorganic matter, namely, carbonic acid and water, etc. By the term running down he means to indicate the passage of molecules from a state of less chemical stability to one of greater, which is the case in the passage of organic matter into inorganic matter. It is well known that organic matter is in a very soluble condition, while car bonic acid and water, into which it passes, pos sess a high degree of stability. Dr. William B. Carpenter believes that what the germ really supplies is not the force but the directive agency; that rather resembling the control exercised by the superintendent builder who is charged with working out the design of the architect. The vital force which causes the primordial cell of the germ first to multiply itself, and then to develop itself, is directly and immediately sup plied by the heat which is constantly operating upon it, and which is transformed into vital force by its passage through the organized fabric that manifests it. Thus heat, acting through the germs, supplies the constructive force or power by which the vegetable fabric is built up. There is evidently in this hypothesis of Dr. Carpenter a double error of idea and of facts. If the germ supplies not the force, but the directive agency, bow can the force-heat supply to the germ the constructive force necessary to build up the vege table fabric, unless the germ in itself could par take of the force of that heat? It would be, in other terms, a force acting on another force, without the latter being influenced by the first force. It is, in one word, an impossibility. As to the question of fact, the production of heat in the germ is, from its origin, at the same time, a cause and an effect, consequently it can not be the primary cause of its development. The decom position, for example, of the carbon from the grain and its reconstruction in carbonic acid can not take place without a chemical action and a reaction, which, in both circumstances, produces heat. Which is the force that precedes here ; is it the chemical, or the calorific action? We could just as well say that the chemical action is the constructive force of germs, and in that case we should come near the running down of Prof. Henry, which is nothing but a purely chemical operation. That which proves the non-identity between the vital force and heat, electricity or magnetism, is the experiments of Dutrocbet on the circular movement of the sap in the cellules of the Mara. He found that heat and electricity act on the circulation of the chara in the same manner as other forces called exciting, in dimin ishing its velocity, causing it to cease altogether, and establishing it anew But the magnetic force, even when it is prodigious, does not exert any influence. From this, Dutrochet concludes that no relation exists between the vital force which produces the circulation of the chara, and that of heat, electricity, or magnetism. Dr. Joseph Le Conte has published ideas very similar to those of Prof. Henry, with which he was acquainted before the issue of that gentleman's memoir, though he has made no mention of it. He advances the idea that the composition of the carbon of the seed and its combination with the oxygen of the air, to form carbonic acid, sets free a force by which germination is effected, and which suffices to organize the rest. By the formation of carhonic acid, he says, the seed loses weight, and decomposition and loss of weight is absolutely necessary to develop organ izing force—the loss of weight being, in fact, the exact measure of that force. If an insoluble food be found capable of conversion into soluble form without loss of carbon, then germination of the seed might take place without loss of weight, by the direct conversion of the heat into vital force. Other authors, as Newport, consider light as the primary source of all vital and instinctive power.
Fowler thinks that not only vitality has correla tion with all physical forces, but it is the• artist of its own cause. Paget advances that every impregnated germ has in itself, and in the pro perties with which it is endowed, the power to develop itself, according to a law, into the perfec tion of an appropriate specific form, when the germ is placed in favorable conditions. Of its action, he says, we may specialize it as the germ power, in consideration of its having its apparent origin and intensest action in the germ. The great doctrine of correlation and equivalency of physical forces. as applied to vital forces, is not yet clearly understood. We must first bear in mind that the laws which preside over vital phenomena, moral or social, differ from the laws of physical and cosmological phenomena only in a higher degree of complexity, always increasing from nutrition to innervation and intelligence. They are only less and less simple, less and less general, and more and more subordinate to the action of a suitable medium. But these three orders of laws, physical, vital, and social, are by no means identical, and there is not even a grada tion, nor an insensible transition from one to the other, as Darwin has supposed in his series of animals and vegetables. The elementary proper ties of matter, according to circumstances, mani fest themselves everywhere simultaneously, obeying the universal law formulated by Auguste Comte, of the equivalence between the action and reaction, the manifestation of one exciting the manifestation of the other or of many others of the same kind. This law is already fore shadowed, and it is the one which we study to day under the name of the law of the conserva tion, -.;orrelation, and equivalency of forces, or of the mechanical equivalency of heat, etc. Experience shows us to-day that from all the bodies which form the inorganic world there are but four principal ones which enter as integral parts of the weft of living beings, and these are oxygen, hydrogen, carbon, and nitro gen. But the fact that living beings are only formed of cosmical elements leads us to an important view in philosophy, that vital force is immanent to organized matter and inherent to the elements which enter its composition, on the same ground by which gravitation, heat, etc., are inherent. One objects in vain that in the vitality of the germ the physical or chemical elements introduced in organic combination acquire new properties which they did not possess previously, as in the case of sulphuric acid, which shows properties different from those which belong to oxygen and sulphur. This objection would stand good if the new compound, sulphuric acid, should manifest properties different from the chemical one. But it is only a transformation of the elements into another chemical element more complex. The same, the elements susceptible of organization, show but equal vital properties in the transformation into other vital elements more complex and less unstable to form vegetable and animal organisms. Consequently, we can not say, as Dr. Carpenter would do, that heat is transformed into vital force by its passage through the organized fabric. Milller has very well shown that in the germ the force of evolu tion reaches its highest power; the nearly microscopic impregnated ovate becomes a body considerably larger; when it leaves the bosom of its parent the evolution is much less rapid; it is still less from infancy to puberty; at the adult state evolution arrests itself, and only makes up its own losses, and finally it ceases to compensate these losses; organic degeneration commences, until it becomes an impossibility to be, according to the philosophic expression of Fontenelle. As observes Littr.% this evolution can be well represented by the curve of a projectile, whose movement is most rapid at the moment of departure. decreases gradually, and ends by stopping altogether. As the force of projection has space for its domain, and the projectile is aimed at a certain point, the force of life has time for its domain, and the germ is aimed at a certain term of duration. The duration of life is further subjected to the physical laws which govern our projectile; for it is an axiom in physics that movement once begun would last forever if it were not at last destroyed by the resistance it encounters. The vital force or the life also would last indefinitely if it were not destroyed by its resisting medium. This medium is the molecules which are constantly added to and taken from the organism, and which consti tute nutrition in the double motion of composition and decomposition, thus offering to us the true definition of life. But this medium being double, that of the cosmological world affects principally our physical organization, and the other in the social world influences principally our moral nature. So the cause of natural death is the resistance of the molecular medium. The source of life is also the source of death. Of the three fundamental activities of matter, nutrition, mobility, and sensibility, a great number of living beings, such as vegetables, do not possess the two last, and still die by natural death. The phenomenon of natural death is then exclusively affixed to the phenomenon of life by the move ment of composition and decomposition which constitutes nutrition. It may still be objected that if vitality consists in the immanence of organic matter itself, why does not life spring from all the possible combinations of that matter. It is in this capital question that the immense influence of the medium on the development of the germ is shown by the following solution : An isolated inorganic molecule does not manifest certain essential properties; for example, does not show any electric or magnetic action unless it is placed beside another molecule, under the con ditions of influence and reciprocity necessary to those effects. Similarly, in the state of isolation, another molecule will not seem to own any affinity of combination without the required contact, immediately on which the chemical action appears. It is exactly what happens with the isolated organic molecule, which will not develop its vital forces unless it be placed in a convenient medium for this new manifestation. The duality, says LittK-, brings in evidence properties immanent to matter, and does not create them. In the supposition of Dr. Carpen ter, the germ would have created a new force, at least a new property, by the transformation of the calorific into vital force. The principle of the transformation of forces was not thoroughly well understood by a great number of philoso phers, for, strictly speaking, there is no trans formation of forces, but a dynamic equiva lence of all the various forces of nature. The properties of life are essentially chemical, as they consist in a continuity of composition and decomposition, the same, at the moment when any chemical combination takes place, a change happens analogous to life. The only difference is, that in chemical action the phe nomena are instantaneous, and the body becomes again completely inert, while in every organism it renews itself as long as the movement of com position and decomposition lasts. All organized bodies placed in a suitable medium present the double movement which characterizes life, by the increase (nutrition) an,d decrease of its ana tomical elements. So the vital force is not a cause; it is, on the contrary, an effect, a modus operandi, an immanence, in one word, the law of organic matter, as universal attraction is an immanence and the law of inorganic matter. The phenomena of vitality are therefore but properties of tissue, which are reproduced after ward in each anatomical element. In fact life seemingly complex, is yet in reality simple.