Julius Ritter von Wiesner

“ No field of research stands so near plant physiology as does animal physiology. Where run, above all, the boundaries of these two territories, when, in the lower stages of plant and animal organisms, it is no longer possible to distinguish with certainty between plant and animal, and when investigations are ever revealing new identities between plant and animal life? To-day we know that plants respire in the same sense and for the same purpose as animals ”

“ The most exact research, even in the domain of matter, has led to impassable boundaries, and the old riddles of the world and all its beings remain unsolved in spite of all progress, and we know, perhaps more clearly than the thinkers of earlier science epochs, that their solution lies beyond the power of the human mind. They remain as unsolvable to the greatest philosopher as well as to the simplest understanding. Other faculties of the mind than those busied in the sober pursuit of science may undertake to show a tangible relation between eternity and our own insignificance. ”

“ Not until synthetical research as to the nutrition of plants made upon living specimens could it be determined on the side of the plant what elements taken up from the soil serve for food, what of the material taken up is used for other purposes, and what is merely neutral. Thus agricultural chemistry, under the influence of plant physiology, has become transformed into agricultural physiology, which to-day is to be counted one of the most important studies that contribute to practical life. ”

“ Even the smallest known living beings, the bacteria, do not come into being parentless, as not long since the last notes of retreat of the defense of spontaneous generation declared. In the organism itself, all that is living proceeds only out of the living—the cell from a cell, the nucleus from a nucleus—and the smallest plastid lying on the very border of microscopic observation proceeds from its like. The possibility enlarged upon by many naturalists, that in the organism living constituents can arise spontaneously, is only a reaction of the old doctrine of spontaneous generation ”

“ Plant physiology has gone its own way, as has also animal physiology, the one not concerning itself about the other; and only enlightened minds have first discerned the inner identities of both, and felt themselves compelled in the solution of fundamental problems to reach out for data into the apparently foreign territory of the other. Thus, one of the greatest animal physiologists of the new era, Ernst von Brucke, who once occupied this same place of honor, to which investigator we are indebted for three great fundamental contributions in the field of plant physiology. ”

“ Plant physiology, like every science, whether it be only through bringing forward explanatory figures or through systematic contribution, has stepped into association with philosophy. The attempt to gain a conception of the molecular or micellar structure of the make-up of cells, or through direct observation to disclose the ultimate life unit of the plant through known facts, belongs, as does the origin of invisible atoms and molecules, in the region of metaphysics ”

“ The present developmental period in natural sciences, so rich in unprecedented results, is characterized by the inductive method of research and by the principle of the division of labor. It required thousands of years to show mankind that the experience of all knowledge takes root, and that the human mind, with its limitations, despite the genius of occasional great men, can only by the combined work of many, each deep in his narrow specialty, arrive at the solution of the great problems of science. ”

“ Like all other sciences, plant physiology has developed in response to the demands of life. As physics and chemistry had their basis in the industries, so plant physiology grew by each experience gathered from agriculture, horticulture, and sylviculture. Even if the origin of plant physiology be not historically demonstrable as a result of the demands of practical life, still a portion of our terminology would bear witness to the correctness of the assumption. ”

“ Ever more and more is disappearing the old opposition between science and practice, and more and more the opinion matures that human progress rests upon the harmonious cooperation of both.
The invasion into the realm of practical life by plant physiology has called forth many relationships between it and the social sciences. What it has done in explaining the exhaustion, what it has contributed to the understanding of the significance of the forest covering for climate and for the cultivation of field and garden vegetation has benefited the social sciences. ”

“ Nothing would seem more natural than that in scientific investigation a plant form and the function of its organs would be equally considered—to consider it as a machine, whose parts are arranged for a purpose and in their combined action accomplish an intended result. ”

“ Really great investigators always recognize that, as Helmholtz opportunely expressed it, knowledge alone is not the end of mankind upon the earth, but that knowledge should be applied in the affairs of practical life. ”

“ Under an appeal to the authority of a great physicist it was claimed that, with the increasing consumption of mineral fuel by the various industries, all supplies of mineral coal would be exhausted within five hundred years. But the last remnants of coal—so it was further claimed—it would no longer be possible to bring out of the earth, because in the meantime the oxygen of the atmosphere, as a result of the enormous increase in combustion, would have decreased to such a limit that the air would no longer be adapted for human respiration. ”

“ So in the progress of research has come about a union between two branches of botany which appeared widely separated, so widely that it was formerly supposed that the chasm between them would never be bridged over, i.e., between systematic botany and physiology in its broadest sense—indeed physiology in the narrowest sense of the doctrine of function. It is plain that all other fields of botany stand in reciprocal relation with physiology, but it required a long time for this state of things to come about. ”

“ The time has passed wherein a man who could give the names of 6,000 plants would because of that be called a botanist, but another who knew 10,000 plants would be designated a greater botanist, and the formerly so-called systematic botany has been thrust back into its proper place of simply a hand servant of the true and exact sciences. ”

“ As the organs, so are the tissues adjusted to each other, and not one of the millions of cells in a tree is without purpose, and if each cell does not stand in fast relation to all others, how also need not each single scientific question be related to all others? This can as little destroy the unity of science as the unity of organic structure of a tree can be destroyed by the fact that each cell does not stand in mutual relation with every other cell. ”

“ Through the use of plant physiology in questions of practical life this science came to be an aid in the administration of justice. The courts request from plant physiologists as from chemists professional opinions, and more than once has the botanical institute of our university been in a position to respond to the requests of the court.
Botany, as is well known, came early to be a strong aid in the medical science, which encouraged not plant physiology but systematic botany—in fact, called it into existence. ”

“ I venture to raise the question here as to why zoology and botany have not chosen the same expression for analogous branches of their science; why under the term "anatomy" botanists and zoologists designate different things. The cause of this lies again in the principle of division of labor, which at first always leads to a sharp separation, and only after advances in scientific work does it bring about union. The development of botany proceeded independently of zoology, and vice versa. ”

“ Only a small part of morphology, which we botanists call anatomy, but which is identical with the histology of the zoologists, developed along with physiology. The greater part of morphology, which corresponds to what zoologists call anatomy, pursued its way independently of physiology. ”

“ What small agencies opposed to the harmonious working of the powers of nature!
Upon how weak a foundation the foregoing hypothesis stands may be seen from the fact that a totally opposite conclusion may be drawn from applying the premises in field experiment, with the use of certain well-established facts of plant physiology. It has been shown, for example, by the French plant physiologist, Boussingault, that the volume of carbon dioxide taken up by green plants is exactly equal to the volume of oxygen given off in the presence of sunlight. ”

“ It becomes even clearer that the synthetical mental work, flowing out of the principle of division of labor, must lead to even greater conceptions, and that the number of men must be even greater who, raising themselves above the level of specialists, will be investigators in the best sense of the word.
Held in bounds by the exact nature of its work, science strides forward, ever attaining more and more of what is seemingly unattainable to the human mind, and likewise ever more clearly recognizing the unattainable as unattainable. ”

“ Slow movements which are to be detected by change of position during growth are common in plant life, but even very lively movements such as are exhibited by swarming of certain reproductive cells (swarmspores and spermatozoids) occur frequently in the lower groups of plants. And shall one not speak of sensitiveness in plants when it is shown that external influences such as light, gravity, etc., act as an irritant which the plant receives, conducts to parts more or less distant and responds to by some definite movement or in general by some definite reaction? ”

“ The collaboration of working material in the form of demonstrated facts on the side of morphology, as well as in the realm of the doctrine of function, has aided in bringing the two nearer together, and the solution of the questions as to the functional significance of morphological structures is in full tide. The most successful has been the union of morphological and physiological knowledge as regards plant tissues, the study of which, as previously mentioned, was from the first often entangled with the doctrine of function. ”

“ The relations of physics and chemistry to plant physiology lie so closely before us and are so well known that I need not here go into nearer details concerning them. But that both these great fields of investigation stand in reciprocal exchange with their younger sister, plant physiology, I will illustrate by a characteristic example. One of the foremost living plant physiologists investigated the working of osmotic force in the life of a plant. ”

“ When investigation in each of the two fields had yielded a rich fund of usable data and had placed them in an orderly arrangement, the union of the two—plant physiology and animal physiology—began. When one takes up a recent work on animal physiology he discovers with satisfaction that already much consideration is given to the facts and conclusions of plant physiology. Recently certain works upon general physiology attest the natural association into which animal and plant physiology have entered. ”

“ If the proportion of carbon dioxide in the atmosphere should notably increase because of the consumption of coal, the plant world would still adapt itself to these changed conditions. This adaptation must, however, be granted to those whose hypothesis leads to such dire consequences as previously depicted; for they must concede that the earlier vegetation of the earth endured a far greater proportion of carbon dioxide than at present, and indeed made use of it. ”

“ The progress of research has reduced to naught all the facts that pointed toward spontaneous generation, and so we find ourselves duly forced to turn away from spontaneous generation and to regard the living substance as given, just as the physicist regards matter, and takes no further thought as to the question of its origin. ”

“ Indeed, more and more we come face to face with the limits of our knowledge. To the Grecian thinkers it seemed a play that allowed the living to spring out of the lifeless, plants or animals from slime or damp earth. But the inductive method has led us thus far to know that, so far as observation can go, the living can arise only from the living. ”

“ As with chemistry and physics, plant physiology stands also in this relation of reciprocal exchange with meteorology and climatology. How greatly plant life is affected by meteorological conditions and how the distribution of vegetation is dependent upon climate is evident every- where, and rich is the knowledge which plant physiologists have gained by the application of the teachings of these two sciences. ”

“ Likewise those branches of plant culture which gave the first impulse toward the establishment of plant physiology have in turn been richly repaid for all the suggestions and usable facts which they furnished. Agriculture, forestry, and horticulture are to-day permeated by the spirit of plant physiology, and what these practical studies have gained in scientific insight is for the most part due to plant physiology. ”

“ All of the earth's carbon is burned up; all of the oxygen allotted to our planet is exhausted. After cooling of the earth, the green vegetation appears and generates free oxygen under the influence of sunlight. This hypothesis derives the whole of the atmospheric oxygen from the green vegetation. Since, at that time, there was no other natural source of oxygen upon the earth besides the green plants, it followed that with increasing combustion the oxygen supply would diminish. ”