Julius von Sachs

“ The inevitable result was that botany ceased to be a science; even the describing of plants which Linnaeus had raised to an art became once more loose and negligent in the hands of such successors; in place of the morphological examination of the parts of plants there was an endless accumulating of technical terms devoid of depth of scientific meaning, till at length a text-book of botany came to look more like a Latin dictionary than a scientific treatise. ”

“ When in a given species, which has remained constant with all its marks for countless generations, the cotyledons, the leaves, the bracts, and the parts of the flower are called leaves, this must be merely the result of abstraction, which has led to the generalising of the idea of a leaf; if we make abstraction of the physiological characters of the carpels, stamens, floral envelopes, and cotyledons, and regard only the way in which they originate on the stem, we are justified in including them in one general idea with ordinary leaves, and to this idea we quite arbitrarily give the name leaf. ”

“ On the contrary, the object of true investigation, whether in philosophy or in natural science, is to make unsparing discovery of existing contradictions and to question the facts until our conceptions are cleared up, and if necessary the whole theory and general view is replaced by a better. In the Aristotelian philosophy and in scholasticism facts are merely examples for the illustration of fixed abstract conceptions, but in the real investigation of nature they are the fruitful soil from which new conceptions, new combinations of thought, new theories, and general views spring and grow. ”

“ In reading the writings of Malpighi, Grew, Mariotte, Hales and even Wolff, notwithstanding many mistakes in details we find a pleasure in the connected reasoning, and in the sagacity which knew how to distinguish between what was important and what was not ; whereas the observers, whom we have now to mention, give us only isolated statements, nor have we the satisfaction of feeling that we are conversing with men of superior understanding. ”

“ So scanty was the stock of knowledge which the founders of vegetable physiology in the latter half of the 17th century found ready to their hand. While the physiological significance of the different organs of the human body and of most animals were known to every one, at least in their more obvious features, the study of vegetable life had to begin with laborious enquiries, whether the different parts of plants are generally necessary to their maintenance and propagation, and what functions must be ascribed to individual parts for the good of the whole. ”

“ The descriptions of species in the 'Prodromus Theatri Botanici' of Kaspar Bauhin (1620) notice all obvious parts of the plant with all possible brevity and in a fixed order; the form of the root, height and form of the stem, characters of the leaves, flowers, fruit, and seed are given in concise sentences seldom occupying more than twenty short lines; the description of a single species is here in fact developed into an art and becomes a diagnosis.
A still higher value must be set on the fact, that in Kaspar Bauhin the distinction between species and genus is fully and consciously carried out ”

“ Botany appeared all at once as a science rich in subject-matter; Schleiden had not only himself made many investigations and broached new theories, but he everywhere drew attention to what was already before the world and was important; for it is not sufficient as regards the literature of a science that there should be good investigators; it is as necessary that the scientific public, and especially the rising generation of professed students, should be well and sufficiently instructed in the art of distinguishing important from unimportant contributions. ”

“ We shall see further on to what surprising conclusions Linnaeus was himself led by his dogma, when he had to take into account the relations of affinity in genera and larger groups. The species and the genus, he continues, are always the work of nature, the variety is often that of cultivation; the class and the order depend both on nature and on art, which must mean that the larger groups of the vegetable kingdom have not the same objective reality as the species and the genus, but rest partly on opinion. ”

“ It is true indeed, that modern vegetable physiology would be impossible without modern physics and chemistry, as the earlier science had to rely on the aid of the physics and chemistry of the day, when she was engaged in forming a conception of ascertained vital phenomena as operations of known causes. But it is equally true, that no advance which physics and chemistry have made up to the present time would have produced any system of vegetable physiology, even with the aid of phytotomy ”

“ In reading the observations of Linnaeus, Gleichen, and Wolff on the sexual theory we step into a world of thought which has long been strange and is scarcely intelligible to us, and which in the present day possesses only a historical interest. Koelreuter's works on the contrary seem to belong to our own time; they contain the best knowledge which we possess on the question of sexuality, and have not become antiquated after the lapse of more than a hundred years. ”

“ The constituting of classes, orders, and genera he calls theoretical classification; the constituting of species and varieties is practical classification. The work of classification carried out by Cesalpino, Morison, Tournefort, and others leads to the establishing of a system; the mere practice of describing species may be carried on by those who know nothing of systematic botany. These expressions of Linnaeus are interesting, because like other remarks of his they show that he placed the establishment and arrangement of the larger groups above the mere distinguishing of individual forms ”

“ These rules were strictly observed by himself in his numerous descriptive works, and thus a spirit of order and clearness was introduced into the art of describing plants, which gave it at once a different appearance from that which it had received at the hands of his predecessors. Whoever therefore compares the 'Genera Plantarum,' the 'Systema Naturae,' and other descriptive works of Linnaeus with those of Morison, Ray, Bachmann, or Tournefort, finds so great a revolution effected by them, that he is impressed with the persuasion that botany first became a science in the hands of Linnaeus ”

“ True investigation of nature consists not only in deducing rules from exact and comparative observation of the phenomena of nature, but in discovering the genetic forces from which the causal connexion, cause and effect may be derived. ”

“ This was the evil result of the old and foolish notion, that the sole or chief business of every botanist is to trifle away time in plant-collecting in wood and meadow and in rummaging in herbaria, proceedings which could do no good to systematic botany even as understood by the Linnaean school. Even the better sort lost the sense for higher knowledge while occupying themselves in this way with the vegetable world ”

“ It was again a misfortune that the systematists in their labours often neglected to distinguish between the search for marks and the use to be made of them; the examination of all possible marks should lead to the establishing the systematic importance of certain fixed marks or their value for classification. When research has done its work, then it is sufficient in exhibiting the system to put forward only the prominent marks; and frequently a single one suffices to unite a natural group. Such a leading mark is like the standard of a regiment ”

“ Since in nature everything is in movement, and every phenomenon is transitory, presenting itself to us in organic life especially as the history of development, all due regard must be paid to this condition of constant motility in forming scientific conceptions. The history of development is not merely to be treated generally as one of various means of investigation, but as identical with investigation into organic nature. ”

“ Whoever has not himself read the elaborate works of Malpighi and Grew, but knows them only from the quotations in later phytotomists, may easily imagine that these fathers of phytotomy had found their way to a theory of the cell, such as we now possess. But it is not so; their works have very little resemblance to modern descriptions of vegetable anatomy; the difference lies chiefly in this, that modern writers in their accounts of the structure of plants start with the idea of the cell, and afterwards treat of the connection of cells into masses of tissue. ”

“ By systematists Linnaeus understands those who occupy themselves with the classification and naming of plants, and he divides them into philosophers, systematists proper, and nomenclators; the philosophers are those who study the theory of the science on principles founded on reason and observation, and are subdivided into orators, institutors, erystics, and physiologists; the latter are those who discovered the mystery of sexuality in plants, and hence Malpighi, Hales, and such men are not physiologists in Linnaeus' sense. ”

“ He was led to distribute all vegetable forms into definite groups not by the fact of natural affinity, which impressed itself on the minds of the botanists of Germany and the Netherlands through involuntary association of ideas, but by philosophical reflection. Trained in the philosophy which flourished in Italy in the 16th century, deeply imbued with the doctrines of Aristotle, and practised in all subtleties of the schools, Cesalpino was not the man to surrender himself quietly to the influence of nature on the unconscious powers of the mind ”

“ As De Candolle's doctrine of symmetry derived the different species of plants from an ideal plan of symmetry or type, so the doctrine of metamorphosis assumed an ideal fundamental organ, from which the different leaf-forms in a plant could be derived. The stem came into consideration only as carrying the leaves, the root was almost entirely disregarded. As the resemblance of nearly allied species of plants suggests itself naturally and unsought to the mind of the unbiassed observer, so also does the connection between different organs of a leafy nature in one and the same plant. ”

“ While Nägeli allowed that Darwin's principle of selection was well adapted to explain fully the adaptation of organisms to their environment and the suitableness and physiological peculiarities of their structure, he pointed out that in the nature of plants themselves there are intimations of laws of variation, which lead to a perfecting of organic forms and to their progressive differentiation, independently of the struggle for existence and of natural selection ”

“ The so-called nature-philosophy, which had long been a great hindrance to morphology, proved in like manner injurious to vegetable physiology; the doctrine of the vital force especially stood in the way of every attempt to resolve the phenomena of life into their elementary processes, to discern them as a chain of causes and effects. The ash-constituents of plants, and even their carbon, were traced to this vital force, and misty notions connected with the word polarity were used to explain the direction of growth and much beside. ”

“ It was of especial importance at that time to insist on the principle that the processes of nutrition within the plant must be judged by the general laws of chemistry; organised beings, said Senebier, are the stage, on which the affinities of the constituents of earth, water, and air mutually influence each other; the decompositions however are generally the result of the influence of light, which separates the oxygen of the carbon dioxide in the green parts of plants. ”

“ The old conceptions of the nature of plants had been greatly modified by Hofmeister's discovery of the alternation of generations, and the reduction to it of the formation of the seed in Phanerogams; in like manner the first beginnings of plant-life, the simplest forms of Algae, exhibit phenomena, which compel us to revise our fundamental conceptions of morphology, if we are ever to be able to give a systematic view of the whole vegetable kingdom. ”

“ No other refutation or rather explanation of teleology in the science of organic life has hitherto been attempted. It has been already pointed out that systematic botany, by establishing the fact of affinity, saw itself compelled at last to give up the constancy of specific forms in order to make this fact intelligible, and here we see how the idea of the adaptation of organisms is found to conflict with causality, unless we assume that the forms which arise through variation only maintain themselves, if they are sufficiently adapted to the surrounding conditions. ”

“ All insight not only into the chemical processes in the nutrition of plants, but also into the mechanical laws of the movement of the sap, and generally into the whole internal economy of plants, depends on a knowledge of the fact, that it is only the cells which contain chlorophyll, and therefore in the higher plants the leaves chiefly as consisting largely of such cells, which have the power of converting the gaseous food supplied by the atmosphere into the substance of the plant with the aid of the materials taken up from the soil. ”

“ We cannot read much of the 'Philosophia Botanica' or the 'Amoenitates' without feeling that we are transported into the literature of the middle ages by the kind of scholastic sophistry which is all that his argumentation amounts to; and yet these works of Linnaeus date from the middle of the last century, from a time when Malpighi, Grew, Camerarius, and Hales had already carried out their model investigations, and his contemporaries Duhamel, Koelreuter, and others were experimenting in true scientific manner. ”

“ To the present day it is always a profitable task to submit the different forms of the Muscineae, the Vascular Cryptogams, and the Gymnosperms to exact investigation in order to ascertain all the details in the process of development in these plants, the formation of the embryo, the succession of cells at the apex, the first appearance and further growth of the lateral organs; and the more careful the observation, the more clearly even to its farthest results does the correctness of the alternation of generations asserted by Hofmeister everywhere appear. ”