Propagation

“ Now if one examines what this matter may be in which the movement coming from the luminous body is propagated, which I call Ethereal matter, one will see that it is not the same that serves for the propagation of Sound. ”

“ C. If it is uniform subject to the variation that may be expected from the particular features of its propagation; or
D. If it is stable such that its relevant characteristics remain unchanged after repeated propagation or, in the case of a particular cycle of propagation, at the end of each such cycle. ”

“ The longer waves travel faster than the shorter, so that each wave is continually being drawn out in length, and its velocity of propagation therefore continually increases as it advances. If we fix our attention on a particular point of the surface, the level there will rise and fall with increasing rapidity and increasing amplitude. ”

“ To understand wave propagation, you must have at least a basic understanding of the earth's atmosphere. The earth's atmosphere is divided into three separate regions, or layers. They are the troposphere, the stratosphere, and the ionosphere. ”

“ Experiment shows that we have at one time a sphere of compression—that is to say, the air is packed closely together; and, again, a sphere
Fig. 5.—Propagation of Sound-Waves along a Cylinder.
of rarefaction, when the particles of air are torn farther apart than they are in the other position. The state of things, then, that travels in the case of sound, is a state of compression and rarefaction of the air. Hence, the particle of air travels differently from the particle of water; it moves backward and forward in a straight line in the direction in which the sound is propagated. ”

“ So a wave rises, catches the light, transmits its motion, and sinks back into sea. So a plant ascends from clay, unfolds its leaves to light and air, flowers, seeds, and becomes clay again. Only, the wave has no knowledge ”

“ The movements in plants under the stimuli of the environment—the twining of tendrils, the effect of temperature, the action of light inducing movements sometimes towards and at other times away from the stimulus, the diametrically opposite responses of the shoot and the root to the same stimulus of gravity, the day and night positions of organs of plants—these, and many others present such diversities that it must have appeared a hopeless endeavour to discover any fundamental reaction applicable in all cases. ”

“ However, to perform this attraction and repulsion, one condition is requisite which is equally necessary in the life of plants, and that is the circulation of the fluids. This circulation we have seen performed in the plant through the polarity between the root and the flower, and therefore in a linear direction from one end to the other. ”

“ And the constantly revolving circle of periodic changes of growth and decay, of life and death, of seed beginning and seed producing—like sunshine and shadow, light and darkness—are opposite points in the circle of electric force and physical life. The growing and dying life-forms intervene between these two points of rest and renewal, of attraction and repulsion, of positive organism and negative diffusion of matter. ”

“ All these three kinds of diffusion—the diffusion of matter, of momentum, and of energy—are carried on by the motion of the molecules. The greater the velocity of the molecules, and the farther they travel before their paths are altered by collision with other molecules, the more rapid will be the diffusion. ”

“ Let the fifteenth motion be that of transmission or of passage, by which the powers of bodies are more or less impeded or advanced by the medium, according to the nature of the bodies and their effective powers, and also according to that of the medium. For one medium is adapted to light, another to sound, another to heat and cold, another to magnetic action, and so on with regard to the other actions. ”

“ Dynamical agents.—The principal agents that are supposed to be concerned in giving circulation to the atmosphere, and in preserving the ratio among its components, are light, heat, electricity, and perhaps magnetism. ”

“ If we suppose that of two equal and adjacent superficial layers of sea-water, one washes over the other by the effect of the wind, for example, the layer that is covered loses its free surface, and with it its proper potential energy, which appears again in an increase of speed. ”

“ Auntie Sue, there are as many currents in our river out there as there are human lives. A comparatively few great main or dominant currents in the river flow—a comparatively few great dominant currents in the river flow of life. ”

“ The proper investigation of a formation can no more overlook development than structure, so closely are the two interwoven. Future research must rest squarely upon this fact.
249. Functions and structures. The functions of a formation are association, invasion, and succession: the second may be resolved into migration and ecesis, and the third, perhaps, into reaction and competition. Formational structures comprise zones, layers, consocies, societies, etc., all of which may be referred to zonation, or to alternation. The term association 200has been used in both an active and a passive sense. ”

“ Numberless experiments have been made on the flow of water in open channels, over weirs, through orifices, and along pipes, and the influences of the nature of the bed, the slope, depth, and size of the channel have been investigated. ”

“ When two trains of sound waves travel through the same medium, each particle of the air, being simultaneously affected by the disturbances due to the different waves, moves in a different manner than it would if only acted on by each wave singly. ”

“ In the periodic movement of plants there are several factors which are predominant, others being of minor importance. The important factors are the effects of light and darkness, of variation of temperature on differential growth, and of thermal variation on geotropic curvature. ”

“ As the waves grow when the winds strive with the other forces which govern the movements of the surface of the sea, as the heap grows when we pour corn out of a sack, as the crystal grows when from the surrounding solution the proper molecules fall into their appropriate places: so in all these cases, very much as in the organism itself, is growth accompanied by change of form, and by a development of definite shapes and contours. ”

“ Why do they not flow together and become one movement? Let us illustrate the matter in a still more materialistic manner. Suppose that we have two streams of water flowing in the same channel and in the same direction, how will it be possible to discover that we have two currents instead of one, and to distinguish which belongs to each? Let us suppose that one of the currents becomes frozen as soon as it reaches our point of observation, and is carried forward as ice. ”

“ We make a circuit, or we cross over and look behind us, and on the very same ground there is nothing to be seen but the rich brown soil swelling in the sunshine, warm with promise, and chequered perhaps here and there with a green blade bursting through the surface. ”

“ The conception of poles of diffusion is of the greatest importance in biology, throwing a flood of light on a number of phenomena, such as karyokinesis, which have hitherto been regarded as of a mysterious nature. ”

“ With regard to the resemblance of the ramifications of the branches and leaves of plants to the traces of the positive electricity, and that of the roots to the negative, it is a circumstance calling for especial remark, that the atmosphere, particularly its lower strata, is generally charged positively, while the earth is always charged negatively. ”

“ In the second case, in growth, which determines the whole shape of the organism, two important factors always co-operate, the inner stimulus, which depends on the specific chemical constitution of the species, and is transmitted by heredity, and the external stimulus which is due to the direct action of light, heat, gravity, and other physical conditions of the environment, and is determined by adaptation (phototaxis, thermotaxis, geotropism, etc.) ”

“ When a conductor is brought near the skin, the snap heard, the spark seen, and the sting felt, are all located together and believed to be different aspects of one entity, the 'electric discharge.' The space of the seen object fuses with the space of the heard object and with that of the felt object by an ultimate law of our consciousness, which is that we simplify, unify, and identify as much as we possibly can. Whatever sensible data can be attended to together we locate together. ”

“ In the marks caused by positive electricity, or which it leaves in its passage, we see the ramifications of a tree, as well as of its individual leaves; those of the negative, recal the bulbous or the spreading root, according as they are clumped or divergent. ”

“ In the channels of rivers the influx and reflux depends upon the current of the rivers, which obstructs the ingress of the waters from the sea, and promotes their egress to the sea, making the ingress later and slower, and the egress sooner and faster ”

“ Phenomena of Stream Currents.—In a paper on the flow and friction of water in open channels, read by Dr. D. T. Smith at the American Association, the questions were asked: Why are there streams? Why are the channels of streams trough-shaped? Why are streams higher in the middle than at the edges? Why is the greatest speed of streams not at the surface but at some distance beneath? ”

“ Not only can the metaphor of intense illumination of a particular field be justly used of it, but we may say that it seems to accelerate the flow of mental process through a particular channel, and so to draw into that channel the contents of other channels in connection with it, just as a rapid flow of water through a pipe sucks in water from connected pipes. ”

“ We have not before us in our scheme the complete evolution of any other wave than this. If, for example, we trace back our own life-wave, we shall find that it ensouled the animal kingdom in the moon-chain, the vegetable kingdom in the second chain, and the mineral kingdom in the first chain. ”

“ In the plant, too, if we are to compare its movements to the reflexes of animals (as has been done by Czapek) , we must distinguish a region of percipience, another of motility, and the p. 45transmission of an influence from the percipient to the motor region. ”

“ The problems in limnology, such as the temperature, stagnation and circulation of reservoir waters; the distribution and relative numbers of different organisms and their relation to chemical analyses are discussed in the light of the results of many years' investigation of water-supplies. The seasonal succession of organisms, their movements with respect to light and other stimuli, and their horizontal and vertical distribution, are in like manner fully treated. ”

“ A circulation, which is but a repetition of rhythmical motion, once set up, organization is complete. Endow this organization with continuity, or the power of repeating itself, which the rhythmical circulation and polarity are capable of doing; endow it with the power of inspiring other colloid and crystalloid atoms with like vibrations, attracting them into its own mass, and then ejecting them again, arranged in form like to the original cell, which it will continue to do from habit, and you have living creatures. ”

“ In the face of the stupendous movements which must have happened in order to bring about the successive growth of forests one above another on the same spot, the question at once arises as to how these movements of the solid earth came about, and what was the cause which operated in such a manner. ”

“ If, in a given region of a mineral-bearing country, the geological formation is such as to lend itself to the easy conduction of currents in one direction rather than in another, the phenomenon referred to may perhaps be partially explained. ”

“ New channels would then be formed, or the rain would so diffuse itself over the surface, that the fall and the evaporation would balance each other.
“Such are the unceasing works of creation, constantly taking place on the exterior surface of the earth; where, though less evident to the senses and experience of man, matter apparently inert is in as progressive a state of change, from the operation of unceasing and immutable causes, as in the visible generations of the animal and vegetable kingdoms. ”

“ Even more, even if there is a field of forces which can propagate at large distance through any kind of material, in order to transmit information, modulation of the energy, depending on the information, is also necessary. ”

“ Could we suppose produced on the present globe some general change of conditions in the sea, on the land, and in the atmosphere—either simultaneously, or by communication from a central area of disturbance —the effects upon organic life might be everywhere manifested, though unequally and variously. ”

“ In the description of direction of responsive movements, confusion is likely to arise unless the point of view be carefully defined. An up-movement of a leaf or a petal means approach towards the growing point of the axis. This may be variously described as movement of closure or of folding. A down-movement may, on the other hand, be described as a movement of opening or of unfolding. ”

“ Let us suppose that one possesses a cause of motion well-determined: for example, a quantity of water, immobile in a reservoir, expecting that one allows it to fall, from a given height, in a smaller canal. ”

“ In this course, matters ran on smoothly for cycles and cycles of years, races of men following races, as waves follow waves. Any perceptible alteration in the relative positions of man and water, at the same time, was in the direction of stricter and more frequent communication between them. ”