Organogenesis

“ There must be a root to take up fluid food; leaves to absorb gaseous matters and elaborate them under the influence of light into new substances to be applied to the growth and strengthening of the plant or to be stored up in particular parts as reserve food; and, besides, particular organs, distinct from the food-organs, for propagation, of the most complicated character, such as are not needed in water-plants, where cross-fertilization, so difficult to secure in the free air, is easily and directly effected. ”

“ Every organism is held together and rendered effective entirely by protoplasm, every organ and part being linked to every other by threads of this substance called nerves. The. life of plants is as dependent upon protoplasm as that of animals, but the protoplasm resides in the cells and controls the vegetative processes. The important fact from our present point of view is that every living organism is an organized mechanism for the storage and voluntary expenditure of energy, and as such does not differ in principle from the chemical products of the inorganic world. ”

“ Corresponding with the absence of mouth, and the absorption instead of the prehension of food, we find that the movements of plant-beings are limited. In the higher Plants, and many lower ones, the colonial organism is firmly fixed or attached, and the movements of its parts are confined to flexions. These are produced by inequalities of growth; or by inequalities of temporary distension of cell-masses, due to the absorption of liquid into their vacuoles, while relaxation is effected by the cytoplasm and cell-wall becoming pervious to the liquid. ”

“ Another step further and we arrive at cell complexes having definite functions, which we call organs. But even the most developed organisms, both of the animal and plant worlds, have relations with cells which stand outside the common organization. By means of micro-organisms the plant gains access to otherwise inaccessible sources of nitrogen, while by means of bacteria the animals make use of the important carbohydrate, cellulose. The bacteria convert the latter, within the intestines, into products which can be further decomposed by the ferments secreted by the glands. ”

“ Plants do not require a stomach,—the humus or soil to which they are fixed is the laboratory, where the nutritive matter is prepared in a state fit for absorption by the spongioles of their roots, and these correspond to the lymphatics of animals; after being taken up by the spongioles, this new fluid mingles with the sap, and passes to the leaves or breathing apparatus of plants, where carbonic acid gas combines with the crude vital liquid, and converts it into a condition fit for all the offices to be performed by the plant: viz. the growth of tissues, and the elaboration of secretions. ”

“ In consequence of the wonderful nutritive activities of cells, we may well speak of them as marvelous magicians. Hertwig, following Haeckel, speaks of many cells as being builders. In the same spirit, we can say that multitudes of cells are expert chemists, artists, sculptors, mathematicians, and so on, in that they make all the myriad chemical products of organic nature, such as spices, pigments, sugars, starches, acids, perfumes, and numerous other substances; they paint in colors that rival the hues of the rainbow; they construct all of the beautiful forms in the animal and plant worlds ”

“ Its bones become mere carbonate and phosphate of lime; the matter of its flesh, and of its other parts, becomes, in the [315] long run, converted into carbonic acid, into water, and into ammonia. You will now, perhaps, understand the curious relation of the animal with the plant, of the organic with the inorganic world, which is shown in this diagram.
Fig. 3.
The plant gathers these inorganic materials together and makes them up into its own substance. The animal eats the plant and appropriates the nutritious portions to its own sustenance, rejects and gets rid of the useless matters ”

“ It will be noticed that the next step in the food cycle is taken by the decomposition bacteria. These organisms, existing, as we have already seen, in the air, in the soil, in the water, and always ready to seize hold of any organic substance that may furnish them with food, feed upon the products of animal life, whether they are such products as muscle tissue, or fat, or sugar, or whether they are the excreted products of animal life, such as urea, and produce therein the chemical decomposition changes already noticed. ”

“ The animal organism is a higher kind of vegetable, the development of which begins with those substances with the production of which the life of an ordinary vegetable ends. As soon as the latter has borne seed, it dies, or a period of its life comes to a termination.
In that endless series of compounds, which begins with carbonic acid, ammonia, and water, the sources of the nutrition of vegetables, and includes the most complex constituents of the animal brain, there is no blank, no interruption. ”

“ A unicellular animal takes organic particles bodily into its protoplasm, and forming around them temporary cavities known as food vacuoles, treats them chemically. The multicellular animal has become shaped so as to enclose a space within its body into which solid organic food-particles are carried and digested, thereafter, in a state of solution, to be shared by the single cells lining the cavity. In this way the animal body does not require so close a relation with the medium surrounding it; its food, the first requirement of an organism, is distributed to it from inside outwards. ”

“ As to somatogenetic factors—granting that structural changes in the body (body-cells) of an animal or plant can profoundly influence in some way the germ-cells, and that, therefore, acquired characters can be transmitted—they are many and well defined. Some of them are the habitat of an animal or plant, the temperature, climate, air, food, soil, water, structures in use or disuse (so-called “Use” and “Disuse”) , etc.
The following brief descriptions will enable the reader to understand that change in the surroundings (environment) of a living creature may cause its body (body-cells) to vary. ”

“ By the animal activities, some of the foods are at once decomposed into carbonic acid and water, which, being dissipated into the air, are brought back at once into the condition in which they can serve again as plant food. ”

“ Some of the unicellular forms of life, and some organisms consisting of a few groups of cells, are, at least in part, equipped with agents (ferments) which are not so precisely directed against certain substrates as the ferments of the higher species, such as plants and animals. ”

“ Every individual organism from the simple plant known as red snow to the oak, from the zoophyte to man is developed from such a cell. This is unquestionable scientific knowledge. The phenomenal process of organic advancement is through growth of the cell by selective appropriation of material, self multiplication of the cell, chemical transformations of the pabulum of the cell, endowment of the muscular and nervous tissues produced by those transformations with vital and psychical properties. ”

“ The evolution of this is proximately dependent on the pabulum afforded it in the Internal Medium, which is the true nutrient material, and to which what is usually called food stands in an external relation: for between the reception of food and its assimilation by the organite, there is an indispensable intermediary stage, through which matter passes from the unorganized to the organized state. This intermediate is now recognized in plants as in animals. The old belief that plants were nourished directly from the soil and atmosphere can no longer be sustained. ”

“ These slightly-different units severally multiply at the expense of the nutriment supplied to the unfolding germ—each kind moulding this nutriment into units of its own type. Throughout the process of development the two kinds of units, mainly agreeing in their proclivities and in the form which they tend to build themselves into, but having minor differences, work in unison to produce an organism of the species from which they were derived, but work in antagonism to produce copies of their respective parent-organisms. ”

“ Everything points to the fact that the cell has agents at its disposal which render it capable of splitting up, into their simplest units, all the complicated substances which are brought to it, or which it itself builds up. In favour of such a view, we may more particularly cite, besides the direct proof of the existence of ferments, the observation that in the metabolism of the cell all the units, out of which the complicated nutritive substances and the components of the cells are built up, are found to occur. ”

“ It must also be admitted that analogy fails to guide us towards any determination on several other points: for instance, whether cells, derived from the same parent-cell, may, in the regular course of growth, become developed into different structures, from absorbing peculiar kinds of nutriment, independently of their union with distinct gemmules. We shall appreciate this difficulty if we call to mind, what complex yet symmetrical growths the cells of plants yield when they are inoculated by the poison of a gall-insect. ”

“ A special place is occupied, at least qualitatively, by all those substances which, like the units of the different organic nutritive and tissue materials—as well as the inorganic constituents, the salts, water, &c.—exhibit no specific structure, and which are common to the most different kinds of cells, as well as to the blood and lymph, as intermediate and final products. ”

“ Such organisms turned out to be the essential factors in fermentation of all kinds, save only those due to digestive ferments; it is such organisms which form alcohol, sour milk, make vinegar, etc. Thus in the organic cycle the rôle of the organisms formed of a single cell at length appeared to be a great one. Everywhere present, borne by the wind, they are the true scavengers; for nothing, no matter how small, can escape them. But they are more than this. Wherever they find organic matter, dead or alive, that can support life, they seize upon it ”

“ Are they substances which play a part in the metabolism of the micro-organisms themselves, or are we dealing with agents which, when passed to the exterior, affect the nutritive medium in some way or another, that is, by either decomposing or reconstituting it? It is quite conceivable that certain micro-organisms have agencies at their disposal, which are able to modify particular nutritive cultures in a particular way. ”

“ To enable us to say that we know anything about the experimental origination of organization and life, the investigator ought to be able to take inorganic matters, such as carbonic acid, ammonia, water, and salines, in any sort of inorganic combination, and be able to build them up into Protein matter, and that that Protein matter ought to begin to live in an organic form. ”

“ It is certainly evident, from what we have said in the preceding chapters, and the experiments we have described, that reproduction is effected by the union of organic molecules returned from each part of the body of the animal, or vegetable, into one or many common reservoirs; and that they are the same molecules which serve for nutriment and expansion of the body. ”

“ Thus, the animal can only raise the complex substance of dead protoplasm to the higher power, as one may say, of living protoplasm; while the plant can raise the less complex substances—carbonic acid, water, and nitrogenous salts—to the same stage of living protoplasm, if not to the same level. ”

“ The elementary unit of plant structure, as of animal structure, is the cell. Within it or its modifications all the vital phenomena of which living organisms are capable have their origin. Upon our knowledge of its minute structure or cytology, combined with a study of its physiological activities, depends the ultimate solution of all the important problems of nutrition and growth, reception and conduction of stimuli, heredity, variation, sex and reproduction. ”

“ There exist micro-organisms capable of acting directly on free nitrogen independent of other plant growth, but the significance of this possible source of plant food is, at the present time, unknown. (5) The micro-organisms of importance to agriculture may be isolated and developed to the exclusion of other organisms of a similar character. ”

“ They become conjoined, numerically and morphologically, in progressive grades of complexity, originating by one kind of alliance the chemical elements which constitute the organic world, and by another the vital elements, which form the protoplasmic basis of animal and plant life. [1053] The organic kingdom rests upon the inorganic, and preys upon it, evolving 285 itself throughout endless time into more highly differentiated forms by its incessant appetite for material acquisition and sensuous stimulation in its environment. ”

“ In fact, many of the organisms are identical with those which cause putrefaction. It will be seen, therefore, that no single species produces the complex chemical and physiological changes which take place, or the bodies necessary for the bating of skin, as some observers have supposed; but the various species succeed one another as the medium changes its reaction and composition, until finally the organic portion is resolved into the simplest bodies such as carbon dioxide, ammonia, and hydrogen. ”