CONSCIOUSNESS IN PLANTS.
Plants, it has been vaguely asserted, differ from animals by not having the power of movement. Rather should it be stated that plants acquire and display this power when it is to their advantage. This will be found to be of comparatively rare occurrence, as they are affixed to the ground, and food is brought to them by the air and rain. Evidence of the very high position a plant may attain in the scale of organization may be seen when we look at one of the more perfect tendril-bearers. As a polypus adjusts its tentacula for action, so a plant places its tendrils. If the tendril be displaced, it sets to work to right itself. Acted on by the light, it bends towards or from it, or disregards it altogether, whichever course may be the most advantageous. For several days the tendrils or internodes of the plant, or both, spontaneously or otherwise revolve with a steady motion. But should they strike some object, they curl quickly around it, grasp it with wonderful firmness, and in the course of a few hours contract into spirals, dragging up the stems, and forming most excellent springs. All external movements now cease, and by growth the tissues soon become surprisingly strong and durable.
Such a movement, as has just been considered, is a widely prevalent one in plants, and is essentially of the same nature as that of the stem of a climbing plant, which successively bends to all points of the compass, so that the tip is made to revolve. This movement has been called revolving nutation by some writers, and circumnutation by others. In the case of the circumnutating movement of the tip of the radicle of some plants, there can be no doubt that it is it that affords the radicle some slight assistance in penetrating the ground. But whether or not a radicle, when surrounded by softened earth, is aided in making a passage for itself by circumnutating, one thing is certain, that is, that this movement, by guiding the radicle along a line of least resistance, can hardly fail to be of high importance. Should, however, a radicle in its downward growth break obliquely into any crevice, or an opening left by a decayed root, or one made by the larva of an insect, and more especially by worms, the circumnutating movement of the tip will materially aid it in following such open passages. Not only our own observation, but also those of such eminent authorities as Darwin and Hensen, conclusively show that roots commonly run down the old burrows of worms.
But radicles of seedlings, as well as those of more vigorous plants, would pass over stones, roots and other obstacles, which they must necessarily encounter in the soil. This they are abundantly able to do, for they are exceedingly sensitive just above their apices, and bend like a tendril towards the touching object. When, however, one side of the apex is pressed by any object, the growing part bends away from that object, and this seems a beautiful adaptation for avoiding obstacles in the soil, and for following the lines of least resistance.
SEEDLING OF WINTER GRAPE.
Earth Cut Away to Show Directions Taken by Tip of Radicle in Avoiding a Stone.
So feeble is the circumnutating movement of the terminal growing part, both of the primary and secondary radicles, that it can assist them but little in penetrating the ground, excepting when the superficial layer is very soft and moist. But it must aid them materially when they chance to break obliquely into cracks, or into burrows that have been made by earth-worms or larvæ. Moreover, combined as it is with the sensitiveness of the tip of the radicle to contact, it can hardly fail to be of the highest importance, for as the tip is always endeavoring to bend to all sides, it will press on all sides, and will thus be able to discriminate between the harder and softer adjoining surfaces. Consequently, it will tend to bend from the harder soil, and will thus take the directions of the least resistance. So it will act if it meet with a stone or the root of another plant in the soil, as must incessantly occur. If the tip were not sensitive, and did not excite the upper part of the radicle to bend away, whenever obstacles were encountered at right angles to its growing direction, it would undoubtedly be liable to be doubled up into a contorted mass. But with radicles growing down inclined plates of glass, as shown by experiment, it has been observed that as soon as the tip merely touched a slip of wood cemented across the plate, the entire terminal growing point curved away, so that the tip soon stood at right angles to its former direction; and thus, as far as the pressure of the surrounding soil would permit, would it be with an obstacle encountered in the ground. Thick and strong radicles, like those of the horse-chestnut, are endowed with less sensitiveness than more delicate ones, and would therefore be the better able by the force of their growth to overcome any slight impediment to their progress. Further, as radicles perceive an excess of moisture in the air on one side and bend towards this side, it is reasonable to infer that they will act in a similar manner with respect to moisture in the earth, for the sensitiveness of moisture resides in the tip, which determines the bending of the upper part. May not this capacity partly account for the extent to which drain-pipes often become choked with roots? The direction which the apex takes at each successive period of the growth of a root, ultimately determines its whole course. It is therefore very important that the apex should follow from the first the most advantageous direction. We can thus understand why sensitiveness to geotropism, contact and moisture should all reside in the tip, and why it should determine the upper growing part to bend either from or to the exciting cause. Darwin has compared a radicle with a burrowing animal, such as a mole, which wishes to penetrate vertically into the ground. By a process of circumnutation, or the movement of his head from side to side, he is enabled to feel any stone or other obstacle, as well as any difference in hardness of soil that may exist, and will therefore turn from that side; but if damper on one side than on the other, will turn thither as a more suitable hunting-ground. Nevertheless, after each interruption, he, guided by the sense of gravity, will be able to recover his downward direction and to reach to a greater depth.
Destruction of the tip of a radicle does not prevent the adjoining part from bending, if this part has already received some influence from the tip. As with a horizontally extended radicle, whose tip has been cut off or destroyed, the part which should bend most remains motionless for many days or hours, even though exposed at right angles to the full influence of gravity, we cannot do otherwise than conclude that the tip alone is sensitive to this power, and transmits some stimulus to the neighboring parts, thereby causing them to bend. Direct evidence of such transmission has been obtained. When a radicle was left extended horizontally for an hour or an hour and a half, by which time the supposed influence will have travelled some distance from the tip, and the tip was then cut off, the radicle subsequently became bent, although it was placed in a perpendicular position. Terminal portions of several radicles thus treated continued for some time to grow in the direction of their newly-acquired curvature, for being destitute of tips they were no longer acted upon by the power of gravity. New vegetative points, however, appeared, and being acted on by this influence coursed themselves perpendicularly downward as was their custom.
Investigation having shown that it is the tip of the radicle that is sensitive to geotropism in the members of such distinct families as the Leguminosæ, Malvaceæ, Cucurbitaceæ and Gramineæ, which may be represented by the Clover, Mallow, Gourd and Rye, we may justly infer that this character is common to the roots of most seedling-plants. Whilst a root is penetrating the ground, the tip must take the incipient step, as it has to determine the direction of the entire root. When, however, it is deflected by any subterranean obstacle, it is essential that a considerable length of the root should be able to bend, particularly as the tip itself grows slowly and bends but little, so that the proper downward course should be recovered. Immaterial as it would seem whether the entire growing part should be so sensitive to geotropism as to effect this movement, or that it should be brought about by an influence transmitted exclusively from the tip, we should, however, remember that it is the tip that is sensitive to the contact of hard objects, causing the radicle to bend away from them, thus directing it along certain lines in the soil where the least opposition interposes. It is again the tip that is alone sensitive, at least in some instances, to moisture, causing the radicle to bend towards its source. These last two kinds of sensitiveness conquer for a time the sensitiveness to geotropism, which, however, ultimately prevails. But the three kinds most often come into antagonism, first one prevailing, and then the other. It would, therefore, be an advantage, perhaps a necessity, for the interweighing and reconciling of these different kinds of sensitiveness, that they should all be localized in the same group of cells which have to transmit the command to the adjoining parts of the radicle, necessitating it to bend to or from the source of the irritation.
Though generally believed by authors that the modification of the upper or lower surfaces of a radicle, whereby curvature is induced in the proper direction, is the direct result of gravitation, yet there can be no question from all that has been said that it is the tip alone that is acted on and that transmits some influence to the adjoining parts, causing them to curve in a downward manner. Gravity, it would seem, does not act in a more direct way on a radicle than it does on any lowly-organized animal, which moves away when it feels some weight or pressure.
When we consider what we have written, it is impossible not to be impressed with the resemblance between the movements of plants and many of the actions performed by the lower animals. With plants an astonishingly small stimulus suffices. One plant may be highly sensitive to the slightest continued pressure, while a closely-allied form just as highly sensitive to a slight momentary touch. The habit of moving at certain periods is inherited both by plants and animals; and other points of similitude have been specified. But the most striking resemblance is the localization of their sensitiveness, and the transmission of a stimulus from the exciting point to another, which consequently moves. Yet plants do not, of course, possess nerves or a central nervous system. May we not therefore infer, and wisely so, too, that with animals such structures but serve for the more perfect transmission of impressions, and for the more complete intercommunication of their several parts?
No structure in plants seems more wonderful, as far as its functions are concerned, than the tip of the radicle. Lightly pressed or burnt or cut, it transmits an influence to the upper adjoining part, causing it to bend away from the affected side. But more surprising, however, is the fact that the tip can distinguish between a slightly harder and softer object, by which it is simultaneously pressed on opposite sides. Let the radicle be pressed by a similar object a little above the tip, and it will be noticed that the pressed part does not transmit any influence to the more distant parts, but bends abruptly towards the object. Perceiving the air to be moister on one side than the other, it likewise sends out an influence to the upper adjoining part, which deflects towards the source of the moisture. When excited by light, the neighboring part bends from the light; but when excited by gravitation, the same part bends towards the centre of gravity. In almost every instance the ultimate purpose or advantage of the several movements can be clearly perceived. Two, or perhaps more, of the exciting causes often act simultaneously on the tip, and one conquers the other, doubtless in accordance with its importance for the life of the plant. The course pursued by the radicle in penetrating the ground being determined by the tip, has acquired for it the diverse kinds of sensitiveness which it possesses; and it is hardly an exaggeration to assert that the tip of the radicle thus endowed, and having the power to direct the movements of the adjoining parts, acts like the brain of one of the lower animals, which organ, seated within the anterior end of the body, receives impressions from the sense-organs, and directs their several movements.
In animals possessed of a nervous system, contractions only follow stimuli, which are carried to the contractile elements by nervous threads, the internal energy representing the external stimulus being called nervous energy or neurism. But where a nervous system does not exist, as is the case in some low animals and in all plants, external stimuli must be justly supposed to be converted into the same form of energy, which in such organisms has a general circulation throughout the contractile protoplasm. The attainment of some position, favorable for the procurement of relief from some unpleasant sensation, or the acquisition of some agreeable one, or for both, is the important thing directly subserved by such movements in the generality of animals. While we have the best of reasons for believing this to be true in the vast majority of animals, because fundamentally their structure is similar to our own, yet the inference that the same is true of the lowest forms of life is justifiable until it is proved to be mistaken.
Whatever be the nature of any movement, whether the projecting of portions of its own body-substance as pseudopodia in the primitive animal, the movement of flagella or cilia in more specialized forms, or the turning of the radicle of a plant-seedling in overcoming some obstacle, there is no resisting the conclusion that the functions of these organs, when once called into existence, are due to stimuli not unlike those which affect the motions of the limbs of the higher animals, and that the preliminary to all such movements, which are not automatic, is an effort. And as no adaptive movement is automatic the first time it is performed, effort, therefore, may be regarded as the immediate source of all movement. Now, effort is a conscious state, and implies a sense of resistance to be overcome. But when an act is performed without effort, resistance has been overcome, and the mechanism requisite for its performance has been completed. Automatism has now been reached. New movements, in their incipiency, necessarily meet with resistance. How this resistance is overcome, there seems to be some diversity of opinion among physiologists and metaphysicians, but it is generally believed that some such mental state as a sensation or a desire, which may or may not stimulate a natural process as an intervening element in the circuit, is concerned in its subduement. That sense-perceptions are stimuli to the immediate appearance of structural changes or movements is shown by the production of color-changes in animals through changes in the condition of the organs of sight and in the bending of the radicle of a seedling-plant a short distance above its tip in obedience to a communication from the tip of a sensation of hardness, caused by contact with a stone experienced in its downward progress in the ground.
TIP OF RADICLE OF SEEDLING MAPLE.
Lower Cells Show Where Consciousness is Supposed to Reside.
New conditions bring forth new acts in animals. No one can deny this statement, as instances of its truth are too frequent to believe otherwise. That such may be predicated of plants, which have not the ability, as a rule, to meet with new conditions by reason of their being affixed to the soil, very few persons are willing to admit; but there is no getting away from the fact. The tip of the radicle of a plant not only has the power, acting as a brain, as it would seem, of guiding the root out of the reach of an obstacle that would be injurious, or in the direction of water when it would be an advantage, but a tendril has also the ability, in obedience to some inherent force, of making its way to a support that has been purposely placed in the near distance for its especial benefit. No external agencies, which the materialistic naturalist has devised for accounting for the movements of plants and low types of animal existences that are devoid of a visible nervous system, can possibly explain these movements, which are only explicable on the theory that nervous energy may be elaborated and be distributed without such a system by and through the general mass of the plant or animal, or by and through such parts as may be necessary to its good.
No one who has experimented with the Droseras or Sundews, can have failed to observe the extreme sensitiveness which resides in their leaves. That these plants manifest a comparatively high order of consciousness, there can be no question. Try them with insects, or rare bits of meat, as articles of diet, and in a few hours, if vigorous leaves have been experimented with, the leaves will have folded around the food and commenced their curious process of assimilation. Mineral substances, such as bits of chalk, magnesia and small pebbles, have no such effect. They seem to ignore these things, just as an intelligent animal would if they were placed by its side. Some experiments made by Mrs. Treat, several summers ago, go far to confirm the statement that plants are endowed with some sort of consciousness. Drosera filiformis was the species used in her experiments. Some living flies were pinned one-half an inch from the leaves, but near their apical extremities. In forty minutes the leaves had perceptibly bent toward the flies, and in little more than an hour had reached the prey, the legs of the latter being entangled and held fast by the tentacles of the leaves. Next, the flies were removed three-quarters of an inch further from the leaves, but the latter, even though bent away from the direction of the light, failed to reach them at this distance. What was it that induced the leaves to stretch in the direction of the flies? Had the sun been shining from that side, it might be said that the movement of the leaves was influenced by its light and heat, for plants as a general rule turn toward that part of the heavens where these energies are the most effective. It cannot be that they were produced by some emanation of moisture from the bodies of the flies, or by any influence that might be exercised by the vibratory movements of their wings. No vain imaginings of such character will suffice for their explanation. The energy necessary to explain this phenomenon must come from within the leaves themselves. There was felt within them a desire for food, and it was this desire that led the leaves to bend away from the light and in the direction of the objects whose presence created in them that sensation. But how they were able, in the absence of any visible sense-organs, to determine the presence of these objects, is difficult to surmise. That they are sensitive to contact is generally conceded. And in them, no doubt, the sense of touch is keenly developed. Granting this to be the truth, then they see, as a blind man sees, by the sense of feeling. Currents of air, established by the vibration of the insect’s wings, impinging upon the epidermis of the leaves, affect the cells beneath, and a nervous influence is started, guided by some central agency, of which we know nothing, causing the leaves to bend in the proper direction. But why the leaves do not thus bend when impinged upon by currents other than those produced by insects, I am unable to say. Even as a blind man, though deaf, is able through the sense of touch to discriminate moving objects by the currents of air they excite, so it may be presumed that the leaves of Drosera are endowed with the same wonderful and intelligent capacity. Such a feeling once experienced would be apt to be known again, for it would become fixed in consciousness by a process of memory. That Drosera, whose habits are more animal-like than plant-like, must occupy a high position in the scale of vegetable life, there can be no reason to doubt from what has been said, and this assumption receives a most remarkable confirmation from the fact that there are evidences, not apparent however, of a sort of nervous system in its make-up, as shown by the discovery of Darwin that by pricking a certain point in a leaf one-half of its substance becomes paralyzed.
Wonderful as these facts are, yet they are not more so than some recent discoveries made by Stahl while studying the simple movements and physical conditions of certain low plants called Myxomycetes. In their young stages these plants wander from the parts of the deposit on which they are creeping, and which are gradually drying up, toward those which are more moist. It is possible, by bringing moist bodies in proximity to any ramifications, to produce pseudopodia, which lift themselves from the deposit, and soon come into contact with the moist object, so as to enable the whole mass of the plasmodium, that is, the large, motile, membranous protoplasmic body formed by the coalescence of the swarm-spores of the Myxomycetes, to migrate thereon. But on the entrance of the plasmodia into the fructifying condition, the Myxomycete quits the moist deposit, technically called the substratum, and creeps upwards on to the surface of dry objects. Unequal distribution of warmth in the substratum and unequal supplies of oxygen and chemical substances soluble in water also cause locomotion in these strange organisms. Let the plasmodia come into contact on one side with solutions of saltpetre, carbonate of potash or common salt, and they at once withdraw from the dangerous spot; but an infusion of tan, or a dilute solution of sugar, causes a flow of the protoplasm and an ultimate translocation of the entire plasmodial mass towards the source of nourishment. Some solutions have an attractive or repulsive effect, but this is in accordance with the degree of their concentration. Unlike what is so natural to plants in general, the Myxomycetes seem to have an aversion to light, as shown by their disposition to withdraw from its presence.
How such tender structures as the Myxomycetes, which are destitute of every kind of external protection, are enabled to carry on their existence, the knowledge of the remarkably delicate reaction of their plasmodia under external influences prepares us to understand. Plasmodia, which are not yet ripe for reproduction, are kept in the moist substratum by their peculiar affection for moisture and utter dislike of the light. But within the darkness and moisture of the substratum the plasmodia do not necessarily remain in one place, for the differences in the chemical composition of the substratum cause continual migrations. Nothing more remarkable can be said of the plasmodia than that they have a wonderful faculty of avoiding harmful substances, and, traversing the substratum in all directions, of taking up the materials they require for food and growth. When, however, their internal changes have advanced so far that the plasmodia are approaching the fructifying condition, they are brought by their dislike for moisture, which now sets in, from the moist ground of forest or wood which they affect to the surface, where they creep up various upright objects, frequently not doing more than forming rigid reproductive capsules at some height from the ground. If, however, the substratum becomes gradually colder, as is the case in autumn, a change which sets in at the surface moving downwards, then the plasmodia migrate into deeper regions still having a higher temperature; but when the cooling proceeds very gradually, which especially happens in large tan-heaps, the plasmodia may in their migration attain considerable depths, where they then change into sclerotia, which are hard tuberous substances, resembling the tubers and bulbs of flowering plants. If, however, the temperature begins to ascend, the sclerotia again germinate, and movement takes place from the deeper and cooler parts to the upper already named.
Thus we see, in the locomotion of the Myxomycetes, extremely interesting cases of movements due to stimulation. Light, heat, moisture and gravitation are, in general, stimulus-movements, and ultimately all growth depends on stimulus-movement, the most primitive kind of protoplasmic movement. No causes other than those which actuate higher organisms can be discerned to account for this lowest type of organic movement. What form of inorganic energy can be cited of sufficient potency to cause the organism to change, and without regard to gravitation or any known form of attraction or repulsion, its position in obedience to stimuli acting for its self-preservation? There is none. In the Fuligo, or Tan Flower, a most remarkable example of designed movement has been observed. This form will, according to H. J. Carter, in its early amœbula stage, when isolated from the sawdust and chips of wood among which it has been living, adapt itself to the water of a watch-glass, or any other shallow vessel, in which it may happen to be placed. But, if the watch-glass be placed upon the sawdust, then it will make its way over the side of the glass to get to the sawdust. Here is probably shown a sense-perception of the presence and position of the tan-bark, as well as a feeling of desire to go to it. May not this desire have been due to a sense of discomfort induced by the surrounding water, or to the calling up in memory of some superior comfort associated with the tan-bark?
Man in his self-complacency thinks that he knows the plants about him. It is true that he has noted their form, their anatomy, their color and their resemblances and differences, but how few have studied them in meadow and woods by the light of a lantern at night or by the silver rays of the moon. One feels on such an occasion as though he had stepped from his threshold upon a foreign soil. Folded leaves and strange sleeping forms will be found to confront you in every direction. Of the nature of the nocturnal movements of plants, as well as their varied and curious attitudes, both in leaves and flowers, much speculation has been rife among botanists. In many flowers the night attitudes have been conclusively shown to have relation solely to their fertilization by insects; but the drooping night attitudes of the leaves were supposed to indicate an aversion to moisture, many plants seemingly verifying the conjecture by the assumption of the same position during rain as in the dew. But when the same pranks were played on a cloudy day or a dewless night, the explanation had to be abandoned. With the clovers, the nocturnal positions of the heads seem to be assumed only in the darkness, and this invariably, dew or no dew, while the leaves appear to revel in the rain, remaining freely open, their chief concern being the protection of the young blossom-clusters.
Were our eyes sharp enough we might discern a certain strangeness in the nocturnal expression of every plant and tree. But in no tree is this expression so remarkably emphasized as in the locust, a member of the same leguminous order of plants with the clover. These trees are especially noted for the pronounced irritability of their leaves, and odd nocturnal capers, whose seeming vital consciousness has induced some authorities to place them at the extremity of their system, in contact with the limits of the animal kingdom. How strange the pigweeds look at night! Their upper leaves, which during the day had extended wide on their long stems, now incline upward against the stalk, enclosing the tops of the younger branches, but still older plants are seen with leaves extended much as at mid-day, but nearly all turned edgewise by a twist in the stem. Circling in a close curve, the creeping-mallow blossom now ignores her proud array of cheeses, and the oxalis flower has forgotten her shooting pods to keep the vigil, closed and nodding upon her stem, while her leaves masquerade in one of the oddest disguises, their three heart-shaped leaflets being seen reflexed and adjusting themselves back to back around the stem with many contortions. Whatever the function of this strange nocturnal movement may be, and it is still a matter of dispute with botanists, one thing we are certain about, that is, its essential condition to the life of the plant, careful experiment having demonstrated, according to one authority, that “if the leaves are prevented from so regulating their surface, they lose their color and die in a few days”—a fact which Darwin has just as conclusively shown to be the case with other plants.
Flowers that bloom by night could hardly be suspected of that vanity which Rhodora has been made to confess by Emerson in his beautiful lines to this flower. Our evening primrose does not bloom in the dark hours for mere sentiment or moonshine, but from a nature which lies, figuratively speaking, much nearer her heart. “Often when the nights are very dark,” says an old writer, “her petals emit a mild phosphorescent light, and look as if illuminated for a holiday. And he who does not fear to be out in her mild and lovely haunt may see a variety of nocturnal ephemeræ hovering around the lighted petals, or sipping at the flowery fountains, while others rest among the branches or hurry up the stems as if fearing to be too late.” From the first moment of her wooing welcome it would seem that our evening primrose listens for murmuring wings, and awaits that supreme fulfilment with joyous expectancy, for it will invariably be found that these blossoms, which open in the twilight, have adapted themselves to crepuscular moths and other nocturnal insects, a fact which finds a striking illustration in the instances of very long tubular-shaped night-blooming flowers, like the honeysuckle and divers orchids, whose nectar is beyond the ability of any insect but a night-flying hawk-moth to attain. True, it is, that in other less deep nocturnal flowers the sweets could be reached by butterflies or bees if the blossoms were left open. But the night-murmurers receive the first invitation, which, if accepted, leaves but a wilted, half-hearted blossom to welcome the sipper of the sunshine. This beautiful expectancy, somehow or other, determines the limit of its bloom. However, in the event of rain or other causes preventive of insect visits, the evening primrose will remain open for the attention of the butterflies during the ensuing day, when otherwise it would have perceptibly drooped, and extended to them but a listless welcome. Most strikingly may this fact be seen illustrated in a spray of mountain-laurel. For nearly a week have I observed in my house these blossoms lingering in patient expectancy, when the flowers on the parent shrub in the woods had fallen several days before, their mission in life having been fulfilled. In the house specimens the radiating stamens, which are naturally dependent upon insects for their release, and the consequent discharge of the pollen, remained in their pockets on the side of the blossom-cup, a support, as it seemed, for the bracing up of the corolla upon its receptacle. But when the operation of releasing the stamens was artificially consummated, the flower-cup soon dropped off or withered upon the peduncle.
Not mainly has the writer, in attributing a phosphorescent quality to the evening primrose, followed the license of fancy, for, if scientists are to be believed, the regular luminous glow of this and other nocturnal flowers has long attracted the attention of the curious, and positive qualities of inherent light have been accorded in many instances. It is true, as one authority asserts, that “the evening primrose is perfectly visible in the darkest night,” from which fact phosphorescent properties have been ascribed to it. Many well-authenticated cases are on record of luminous, electrical, lightning-like phosphorescence playing about flowers, the daughter of Linnæus having been the first one to note such an interesting phenomenon. Similar flashes or corona have been observed in nasturtiums, double marigold, geraniums, red poppy, tuberose, sunflower and evening primrose. According to various authorities, and it would be a rash and presumptuous commentator who would dare to challenge such an array of competence, many beautiful surprises await the traveller among the dewy shadows. Whoever has made such a journey will not only return with the consciousness that he has doubled his possessions, but that he has also explored a new world—a realm which he can look in the face on the morrow with an exchange of recognition that was truly impossible yesterday.
Whether or not all the facts that have been adduced show that plants are conscious organisms in the particulars for which it is claimed, it matters not, for enough have been set forth to demonstrate beyond the shadow of a doubt the position that they are endowed with a consciousness, no matter how infinitesimally small a part it plays in nature. Everyday observation of the botanist teaches the fact. Sensation, which is consciousness, has preceded in time and in history the evolution of the greater part of plants and animals, unicellular and multicellular, and, therefore, if kinetogenesis, or the doctrine of the effects of molar motion, be true, “consciousness,” as Cope alleges, “has been essential to a rising scale of organic evolution.” Animals which do not perform simple acts of self-preservation must necessarily, sooner or later, perish. Impossible it is to understand how the lowest forms of life, wholly dependent as they are on physical conditions of many kinds, should to-day exist if they were not possessed of some degree of consciousness under stimuli at least. We have but to picture to ourselves the condition of a vertebrate, without general or special sensation, would we obtain a clear perception of the essentiality of consciousness to its existence. If now use, as has been maintained, has modified structure, and so, in coöperation with the environment, has directed evolution, we can understand the origin and development of useful organs, and also how, by parasitism, or some other mode of gaining a livelihood without exertion, the adoption of new and skilful movements would be unnecessary, and consciousness itself seldom aroused, for continual repose would be followed by sub-consciousness, and later by unconsciousness. Such appears to be largely the history of degeneracy everywhere, and such is, perhaps, in a great measure the history of the entire vegetable kingdom, for plants, from their ability to manufacture protoplasm from inorganic substances, do not bodily move about in quest of food as animals generally do, and therefore require no conscious conditions, it would seem, to guide their movements. They become fixed, and their entire organization, except in specialized instances, becomes monopolized by the functions of nutrition and reproduction. Their movements are mostly rhythmic or rotary, but that they exhibit the quality of impromptu design more frequently than scientists are willing to allow must be admitted, or facts and the conclusions which naturally flow therefrom constitute no criteria of judging. Too much stress, I fear, is placed in these days upon the action of certain supposed forces that are resident in the plant’s or animal’s environment in accounting for its behavior, to the utter exclusion of any energy that may be acting from within the organism itself. “That consciousness as well as life preceded organism, and has been the primum mobile in the creation of organic structure,” as Cope assumes, there is no doubt; but that it early abandoned the vegetable world, and also that all the energies of vegetable protoplasm soon became automatic, causing plants in general to become sessile, and therefore parasitic and in one sense degenerate, I cannot wholly accept. That insects have, in the matter of evolution of plant-types, exerted considerable influence on the conditions of almost all of their organs, the forms of the organs of fructification and especially of the flowers, through certain stimuli and strains to which they have become subjected by reason of these insects and their occupancy of parts as dwelling-places, there can be no doubt; and it is probable also, as has been maintained, that we owe to insects, directly or indirectly, not only the forms, but also the colors of the flowers, and their odors and peculiar markings as well. And thus while degeneracy, as observed in the abortion of ovules, carpels and perianth, may be seen everywhere, which the influences that have acted upon them have induced, yet it is the height of presumption to assert that consciousness has entirely abandoned the members of the vegetable kingdom, and that they are reduced to the condition of mere automata. It is true, as has been claimed, that the permanent and the successful forms of organization have ever been those in which motion and sensibility have been preserved, as well as the most highly developed; and just as true it is that plants, even though fixed to the soil and unable to effect a change of environment in consequence, are not so incapable of conscious actions as not to be able to meet any changes, and these changes do very often occur, that climate, new conditions of soil, helps or hindrances to growth and wear, may bring about. That they must adapt themselves to such changes, or perish in their struggle to exist, none can question. It is not enough to say that natural selection affords an explanation of every phenomenon that they may exhibit. There is an energy within the plant, think and write as we will, and it is this that comes to its aid and directs the movement that will be productive of the most good.
Concluding, then, let me aver that no plant can exist or fulfil its allotted part in the drama of life without the possession of some form or degree of consciousness. If it be true that life and consciousness preceded organization, and the statement can hardly be disputed, and have been the primum mobile in the creation of organic structure, what reason, seeing that life necessarily persists in vegetable organism, can be given for their dissociation in existing forms of plants, as seems to be the tendency of modern scientific thought? That plants once possessed consciousness, there can be no difference of opinion. Well, then, what has become of this consciousness? It could not have been destroyed, for energy or force, and consciousness certainly must be placed under this category, can never be destroyed. I repeat the question. What has become of it? Either it exists in the plant in a dormant condition, awaiting opportunities to call it into existence, or it has returned to the great Source of all consciousness, whence each individual organism, whether of plant or animal, obtained its quantum. It still exists, but how or under what conditions, I cannot affirm, and is to plants what mind is to man and animals, controlling their actions when such are for their well-being and good. If mind persists in a future state, then consciousness, which may be considered as mind in plants, must also persist, for it is not at all likely that the Source of all consciousness, which we worship as God, the Creator of all things, could be unmindful of the least of His children.