Structural Botany and Vegetable Physiology 735 which, though continuing the fundamentally false distinction between trees and herbs laid down by Caesalpinus, separated monocotyledons from dicotyledons, and may be regarded as the most notable approach to the natural system. These various descriptive works contained of course many references to, and discussions on, the structure and uses of the parts of plants; but they were for the most part fragmentary, and in some cases erroneous. In the latter part of the seventeenth century a remarkable advance was marked by the almost simultaneous production, in 1671, of preliminary accounts of the structure of plants by Malpighi and Nehemiah Grew, followed by the fuller work of Malpighi in 1674, and of Grew in 1682. These works cover very much the same ground and in many cases announce the same discoveries arrived at independently, though Grew in his later work had the advantage of knowing what Malpighi had written. The two, at one bound, brought up the knowledge of the anatomy, and especially the finer anatomy, of plants, from a mere collection of scattered and more or less dubious observations to a solid and compact body of exact doctrine. They showed-Malpighi writing with the greater lucidity and pointedness, and Grew with more copious details that the elements of the structure of a plant were woody fibres, spiral vessels, and the cells of the parenchymatous parts with the addition of the less general lactiferous vessels. They further showed how these elements were built up in the stem, with its bark, wood and pith and medullary rays, in the roots, leaves, flowers, fruits and seeds; and how the elements, forming the roots, were first gathered up into the stem and then separated again into the branches, thus establishing the continuity of all parts. They thus laid the foundation of the Histology of Plants, to which Robert Hooke and Leeuwenhoek made some slight additions, but which otherwise remained untouched for more than a hundred years. In describing structure, both Malpighi and Grew in their works introduced considerations of function, the former more happily than the latter. Looking upon the woody fibres as organs for conducting fluid or sap, the spiral vessels or tracheae, as he called them, as air passages, and the lactiferous vessels as channels for special juices, Malpighi was led by the study of the young cotyledons of germinating seeds (which he recognised as leaves) to the important view, that the crude sap carried upwards from the roots was in the leaves, under the influence of the sun's rays, elaborated into more perfect sap; and that this, descending again, was carried to growing parts or stored up in various places. And Ray, who treats of Vegetable Physiology incidentally only, had independently arrived at the same conclusion. As in his researches on the animal body, so in his study of plants, Malpighi does not attack the chemical side of the problem of nutrition; and Grew, who did attempt it, was not very successful. Except for this want of chemical truth, Malpighi and Grew may be said to have laid some of the 736 Sexuality in plants. — Zoology foundations of Vegetable Physiology as well as those of Vegetable Histology. One other important advance was made in the seventeenth century. Although from quite early times botanists had recognised that some plants might be spoken of as fruit-bearing and female and others as not fruit-bearing and male, and Theophrastus had called attention to the fact that the female date-palm only produces fruit when the dust of the male is shaken over it, the view that the influence of a male element was necessary for the full development of a female organ into fruit was rarely expressed, and then in most cases obscurely. Some botanists, for instance Caesalpinus, held that no such influence was necessary; and Malpighi in his very careful account of the development of seed and of the earlier stages of the growth of the embryo refers nowhere to any influence of the pollen, which he otherwise carefully described; he seems to have regarded the seed as merely a kind of bud. Grew ascribed some subtle influence to the anthers, but his account is most obscure; and even Ray, who seems after some hesitation to have finally accepted the doctrine of sexuality, never attempted to obtain proof of the matter by experiment. In 1691, however, and more fully in 1694, Rudolf Jacob Camerarius (1665-1721) gave the direct experimental proof - namely, by removing them—that the anthers were essential to fertilisation, and showed by his careful account that he had fully grasped the importance of his discovery. - The study of animals made marked progress in the seventeenth century in two directions, affording in this respect a parallel to the study of plants. In the preceding century and even earlier the spirit of the new method of research had led men to be no longer content with the study of Aristotle's writings and the fabulous stories of travellers, but to observe for themselves, to describe the features and habits of such animals as came within their notice, and even to attempt a classification. As the zeal for travel, which was one of the marks of the age, brought back to Europe not only accounts but actual specimens of creatures hitherto unknown. and collections began to be made in the form of museums, both private and public, as well as of zoological gardens (the date of the earliest of these it seems difficult to fix), a body of exact zoological knowledge gradually grew up, expounded in such works as those of Conrad Gesner (1516-65) and of Aldrovandus (1527-1605). This study of the Natural History of Animals, pursued mainly out of natural curiosity, and not for its use in Medicine or otherwise, continuing to make great progress in the seventeenth century, found a brilliant expositor in the man of science who was doing a like service for Botany namely, John Ray. Francis Willughby (1635-72), first the pupil, and then the intimate friend of Ray, had studied animals while Ray was chiefly studying plants, the two carrying out their studies in close concert; but he died early without having published any important Systematic Zoology and Comparative Anatomy 737 part of the abundant material, especially on fishes and birds, which he had gathered together. This work of Willughby, Ray, who had himself a large share in it, brought out after the former's death. He himself produced a large work on quadrupeds and reptiles; and a like work of his on insects was published after his death. Thus Ray, making use of Willughby's labours, gave a full account of the greater part of the animal kingdom; and the classification which he adopted was not only accepted at the time, but has remained, with changes and extensions, the basis of the classification in use to the present day. Ray in fact may be regarded as the founder of Systematic Zoology. The systematic zoologists paid more attention to external features than to internal structure; but it was only natural that the enquirers who found the actual dissection of the human body so fruitful of new truths and new ideas should turn to the dissection of the bodies of animals ; and, indeed, many of the anatomists, notably Fabricius, following the example of Galen, did, in a more or less desultory fashion, examine and describe the structure of various animals. In the middle of the seventeenth century, however, two men took up this work in a more thorough fashion, being therein greatly assisted by the introduction of the microscope. Malpighi's account of the anatomy of the silk-worm (1669) was the pioneer of exact Comparative Anatomy and Histology in respect to animals, doing for them what his Anatome Plantarum did for plants. About the same time, Swammerdam was applying the same methods, in a still more thorough and extensive way, not only to various kinds of insects in their several stages of metamorphosis, but to other animals as well, such as the snail and the frog. A few only of Swammerdam's results were published in his lifetime; the greater part did not see the light until long after his death, when in 1737 Boerhaave published under the title of Biblia Naturae the writings which he had left behind. These two men, Malpighi and Swammerdam, may be said to have created the science of Comparative Anatomy. The same century saw, however, other important works. Leeuwenhoek, applying the microscope in all directions, discovered spermatozoa, made known infusoria and rotifera, and studied hydra and aphthis. Malpighi, carrying the study of the formation of the chick in the egg far beyond the rough attempts of Fabricius, laid the foundations of Embryology. Francesco Redi (1670), in proving that maggots were not bred out of mere corruption, since they did not appear in rotting flesh if the access of flies was prevented, not only dealt a heavy blow at the widely accepted theory of spontaneous generation, but introduced a new and fruitful method of Experimental Biology. Of less, perhaps, but still great value, were Redi's works (1684) on the structure and economy of parasitic animals, and (1664) on vipers, in which he gave an admirable account of the poison mechanism, and incidentally showed that the poison was not absorbed by the alimentary canal. He also wrote on the C. M. H. V. 47 1728 torpedo. Stensen carefully described the anatomy of the ray; and Frederik Ruysch (1638-1731), by the singular skill with which he developed the art of injecting blood vessels and other channels with coloured materials, assisted largely the progress not only of human but also of comparative anatomy. In the sixteenth century, and even earlier, the new spirit of observation and enquiry did not fail to turn men's minds to the phenomena of the earth, especially as disclosed by mining operations. It led George Bauer (Georgius Agricola, 1494–1555), who lived near the mines of the Erzgebirge, to a very extensive study of metals and other minerals, and he may be said to have laid the foundations of Mineralogy. Among the objects of which he spoke as fossilia he included the remains of extinct animals; but he did not recognise these as such; he made no distinction between them and minerals possessing definite forms, and thought that they all arose in the same way - that all were the products of natural forces. - While minerals were thus being studied from the mining point of view, it was natural that the men who had been led to study animals and plants, and especially those who gathered collections of these and formed museums, should also turn their attention to minerals, precious stones and fossils. Thus Caesalpinus, Conrad Gesner, Aldrovandus and others treated of these as well as of plants and animals. But they, or at least the majority of them, failed to distinguish between ordinary minerals and the mineralised remains of extinct animals; they spoke of the latter as "sculptured minerals," lapides figurati, and regarded them as lusus naturae, as the products of a mysterious vis plastica or lapidifica. This view, however, was not accepted by all. Even in the fifteenth and, later, in the sixteenth century both those remarkable men, Leonardo da Vinci and Bernard Palissy, "the Potter," (1499-1589), had argued forcibly that these fossils must be the remains of animals and plants which were once living. Yet it held its ground in a remarkable manner far on into the seventeenth century, and did not wholly disappear until the end of that century or even the beginning of the next. Hence, though many collections of fossil plants and animals were made, and many specimens carefully described, little use was made of them to interpret the history of the earth. the seventeenth century the labours of John Woodward (1665, who made large collections of fossils and minerals and most carefully studied and described them, were perhaps the most effective in establishing the truth that fossils were really the remains of plants and animals which were once alive; and in this he was vigorously supported later by Jean-Jacques Scheuchzer (1672-1733) and others. But Woodward and the rest were content with the explanation that the distribution of these fossils at different places and at different depths from the surface was Anticipation of Geology. Early Academies 739 simply a result of the Mosaic deluge. And indeed, though Athanasius Kircher (1602-80) studied and carefully described volcanoes, and though a posthumous work by Robert Hooke on earthquakes shows that he had grasped the idea that fossils might be used as helps to tell the tale of the earth, most of the attempts of the century to explain how the earth had gained its present features were either fantastic developments of the biblical history or speculative cosmogonies like those of Descartes and Leibniz. One man only followed in the path begun by Da Vinci, who had not only contended that fossils were the remains of once living plants and animals, but had also suggested how their presence in various places and at various depths could be explained by the action of water. That singular man, Nicolaus Stensen, in a little tract, De solido intra solidum, published in 1669, a brief preliminary statement (intended to be followed by a larger and fuller work which, however, never saw the light), after showing that fossils were really the remains of plants and animals, went on to infer from the features of the soil in which they were embedded, and from the other circumstances of their occurrence, the changes which had taken place leading to their deposition. The little work was in fact a remarkable anticipation of modern geological doctrines; but it produced no lasting effect and was soon forgotten. The seventeenth century passed away without any advance on the beginning thus made. The story of the progress of science in the seventeenth century would not be complete without a reference to the scientific societies which were tokens of the scientific activity of the time, and powerfully promoted the advance of scientific knowledge. During the fifteenth century the friends of the new studies began to form, in various cities of Italy, clubs or societies, the members of which, meeting together under the protection and very frequently at the house of some great or wealthy personage, used to discuss and take measures to promote the new ideas which were stirring them. A society of this kind, founded at Florence by Cosimo de' Medici, which devoted itself to the study of the writings of Plato, thought to emphasise its platonic character by calling itself an Accademia; and the name after a while came to be adopted by similar societies. During the sixteenth and seventeenth centuries these societies, or Academies, multiplied rapidly; they became the fashion, so that nearly every large city in Italy had at least one, and the chief cities several. Most of the Academies busied themselves with letters or with art; they assumed fantastic names; they were in many cases short-lived, some of them being put down by the Church, or remaining insignificant. Towards the middle of the seventeenth century the progress of scientific learning in its various branches received a great stimulus, in several European countries, from the foundation of Academies or |