Biology

BIOLOGY. - From the Greek βίος "life" and λόγος "discourse, reasoning," it is the science of life in its normal and pathological phenomenology. According to Treviranus (1776-1837), who first used the term, biology means: the study of the different forms that organic life assumes, of the different conditions and laws that govern its existence, and of the causes that determine its activity. With this original concept, a vitalistic stamp is attributed to the term, inasmuch as the totality of the phenomena that relate to it are subject to forces that are not found in the inorganic world. Very many biologists are even today convinced that if the organic and organized world is subject to the laws of physics and chemistry, it is also dominated by forces unknown to the physical world; others, on the other hand, hold that the "vital" forces are obscure and apparently metaphysical, but that with the progress of science they too will be evaluated by the same laws of the physical world. This materialistic current concerning life finds in Lamarck one of its first proponents.

The term biology can be used in a broad sense, according to the definition given, as well as in a narrow sense, that is, as the study of the habits and mode of life (ecology) of the various animals and the various plants. By the term general biology is meant a discipline that considers all vital phenomena synthetically, so as to discern the general laws that guide them. If we refer to one of the most modern treatises of general biology, for example that of Cotronei, we see that the subject matter is divided into the following parts and the following chapters: part 1 deals with "biological organization" with chapters on the limits of the biological sciences, on mechanism and vitalism, on the origin of life, on the differences between animals and plants, on the colloidal structure of protoplasm, on the cell in general, on the chemical constitution of organisms, on the vital activities of cells, on cellular and organismal reproduction, on embryonic development, on the structure of tissues, on growth, old age and death. Part 2 deals with "heredity and biological environments"; part 3 with "morphology," that is, the anatomy of living beings (in this book limited to vertebrates for didactic reasons) treated comparatively, so as to comprehend the significance of structures.

The field of biology is vast, and therefore various biological disciplines have arisen. One can first of all distinguish an animal biology, which deals with the fauna, and a plant biology, which deals with the flora, although the division between the two kingdoms is not clear-cut, owing to the presence of living beings that represent intermediate conditions. Organisms can be studied according to different aspects: their structure, their activity or function, their anomalies. We thus have three vast groups of disciplines, which we comprehend under the terms general morphology, general physiology and general pathology. To morphology belong cytology, which studies the cell, embryology, which studies the phases of development, histology, which considers the association of the cells that constitute the tissues of multicellular organisms, organology, which studies the organs, and anatomy, which studies the various parts of organisms. Particular disciplines are comparative anatomy, which investigates, through the comparison of structure in the various animal species, the morphological significance of the various structures, and human anatomy, which deals exclusively with the structure of man. To physiology belong biophysics and biochemistry, which deal respectively with the physical and chemical aspects of the vital functions; human physiology deals with the functions of man considered as an animal. Pathology, which treats of the abnormal and morbid processes of organisms, is distinguished into plant, animal and human pathology. Human pathology is distinguished into medical and surgical. One side of pathology is that studied by general pathology, which deals with the generic data of human morbid processes, such as the onset of the processes, their phenomenology, the way of distinguishing and classifying them, the study of their course, the predictions concerning the outcome, and the outcome itself. Disciplines connected with it are bacteriology, which studies the life of pathogenic and non-pathogenic microorganisms (which do or do not cause diseases), parasitology, which deals with the organisms that live on other organisms, causing them harm and lesions, and teratology, which investigates monstrosities, bringing to light their embryological mechanism. Other branches of biology are zoological and botanical systematics, which deals with the classification of animals and plants into related groups, genetics, which deals with the transmission of hereditary characters and their behavior in descendants, ethology, which studies organisms in their environment (biogeography is a branch of it and studies the factors that govern the geographical distribution of organisms), oceanography, hydrobiology and limnology, which study respectively life in the seas, in fresh waters in general, and in lakes in particular. Among the biological sciences, at least according to some of its aspects, psychology is to be included, and precisely as experimental psychology and comparative psychology, which study the behavior of animals.

A series of biological disciplines has an eminently practical character: agricultural biology, arboriculture or silviculture, horticulture, floriculture, plant pathology, agricultural bacteriology, agricultural entomology, hydrobiology applied to fishing, zootechnics, poultry farming, sericulture, etc.

Finally, we can group together all the biological disciplines that concern the human species, such as anthropology, which deals with the various human races, human paleontology, which deals with fossil men, anthropometry, eugenics, human heredity, ethnology, ethnography, sociology, constitutional pathology, human psychology, and finally the whole group of the medical sciences.

Alberto Stefanelli

HISTORY OF BIOLOGY

The study of b. began in the Italic schools in the 6th century B.C. From that epoch dates the first sketch of a science which, while continuing to recognize the Divinity as the first cause of all things, investigates, on the basis of biological experiment, the secondary causes, which are accessible to human study.

In this manner Alcmaeon of Croton, the first of the great "physiologists" (students of nature), expresses himself. With him begins anatomical investigation and the attempt to explain physiological phenomena. The first biological laws are formulated with the concept of isonomia, by which the organism is considered to be composed of various pairs of opposites, from whose just proportion the normal state emerges, while from their disproportion disease (monarchy) has its origin. Contemporary, and in dispute over priority, is the principle of enantiosis, devised by Pythagoras. While the latter, however, has a predominantly cosmic character, that of Alcmaeon is more directly biological. To Empedocles of Agrigentum (6th-5th century B.C.) is due the specification of isonomia with the recognition of four elements (water, air, earth and fire) which he calls "roots of all things." The animal organism too would have such a constitution, and its various functions would be carried out by virtue of the magical law of similarity. To Philolaus of Tarentum is due the fundamental principle of the correlation of the microcosm with the macrocosm. From the Empedoclean principle of the four elements, the Hippocratic school developed the humoral concept, in which the elements were replaced by the humors (black bile, blood, phlegm, yellow bile). This theory laid solid foundations in biological thought, reigning until the last century, while today it rises again in the theory of hormones. In it too health consists in the perfect proportion, while the corruption or excess of one of them constitutes disease. To Aristotle is due the broadening of the study of b. and the establishment of a doctrinal system; for which reason he was called the father of this science. His is the first attempt at a classification of living forms, in which these, by degrees, starting from plants, through mollusks, arthropods, crustaceans, reptiles and mammals, reach as far as man. He was the founder of comparative anatomy and the first, it is said, to make anatomical drawings. He recognizes the four Empedoclean elements to which he adds a "fifth essence." To him is due, therefore, the principle of fusing science and philosophy in the same method of research, which was later to be replaced by the inductive method of Galileo; and likewise the establishment of the doctrine of spontaneous generation, a principle which was subsequently distorted and exaggerated (v. GENERAZIONE SPONTANEA).

Plant b. had its first student in Theophrastus of Eresus (4th century B.C.), a pupil of Aristotle. To him is due a book on the History and one on the Causes of plants. The study of b. had its apogee, as regards anatomy and physiology, in the Alexandrian schools (end of the 4th century B.C.), especially through the merit of Herophilus and Erasistratus (v. ANATOMIA). Other students worthy of note were, although earlier and therefore less evolved, Dioscorides of Cos and Praxagoras of Cos. B. has a large part in the Natural History of Pliny (23-79 A.D.). In it are treated exhaustively, for the epoch, botany, zoology, medicine, together with mineralogy, geography, etc. This work has the merit of having collected what was known at that time. A contemporary is Pedanius Dioscorides of Anazarbus, author of a very extensive work on plants, animals and vegetables which he considers, however, only from the therapeutic side. From this work almost all later authors who treated the same subject took their cue (Pseudo-Apuleius, Macer Floridus, etc.). Many Fathers of the Church also occupied themselves with b., in order to glorify the divine creation, in their homilies and in the hexaemera (St. Ambrose, St. Augustine, Nemesius, etc.). Important among these is St. Basil, who devoted particular interest to scientific studies. Noteworthy too are St. Hildegard, author of the celebrated Physica, and St. Isidore of Seville, author of the Origins; nor should the Speculum Naturale of the Dominican Vincent of Beauvais be forgotten, very interesting since it gives us the picture of knowledge on the subject. More important, however, for a principle of freedom of scientific thought, is the work of St. Albert the Great, unfolding also in the biological field, since he had the boldness to set his own thought against the Plinian assertions accepted, in general, dogmatically. Another student of b., although he directed the study of plants to their pharmacological uses, was Simone Cordo, called Simone Genovese, chaplain of Boniface VIII, author of a Clavis sanationis. With the establishment of Renaissance thought, b. too received a notable impulse. The renewed study of nature drives scientists and philosophers to attempt its mysteries, whence naturalistic philosophy and so-called natural magic develop, to be considered a precursor of the experimental method. Leonardo da Vinci, with his anatomical studies and his observations of physiology and botany, merits particular attention first of all. He studied the growth of plants, discovered the law followed by the birth of leaves on branches, saw the concentric rings of the stem, from which the age of plants is established, intuited the existence of a circulation in plants, tested the action of toxic substances on the development of plants, and obtained alcoholic solutions of chlorophyll. In 1513 Leo X instituted the first chair of simples, to which Giuliano da Foligno was called. At the same time there was formed, in the garden of the Belvedere, a first garden of simples. Following the spirit of the Renaissance, the revision of the ancient works is also accomplished in b.: important for this purpose is the De erroribus Plinii et aliorum etc. of Niccolò Leoniceno. The first botanical gardens arise, besides that of Rome, of which the most celebrated were that of Pisa (1544) and that of Padua (1545). Venice would have had one as early as 1533. Eminent students were L. Ghini, F. Bonafede, the Anguillara (L. Squaleno) for plant b. and systematics and the distinction of new species; P. A. Mattioli, C. Durante, F. Calzolari, P. Castelli, B. Maranta, F. Imperato, for the same studies and for the pharmacological application of the use of plants. A classification is attempted (M. Lobel-A. Cesalpino); to the latter are owed very important observations in the whole field of plant b. A particular impulse to the knowledge of the flora of the countries of the new continent was given by P. Alpino, who described well that of Egypt, while among foreigners J. Ruel (1479-1589) and C. de Lécluse (1526-1609) are to be remembered.

In animal b., the discovery of the circulation of the blood by A. Cesalpino and R. Colombo was extremely important. The humoral theory, on the other hand, remained unchanged (even though there were attempts to alter it), and the function of the various organs was traced back to the virtutes. For zoology, the studies of U. Aldovrandi were interesting, while on the threshold between the 16th and 17th centuries stands the surgeon M. A. Severino (1580-1656), a student of comparative anatomy and a convinced upholder of the uniformity of the intimate structure of all organized beings, which would differ from one another only in outward appearance. He extended his conclusions to the plant kingdom as well. His Zootomia democratica must be considered the first treatise on comparative anatomy. The study of embryology begins in this period with the research of G. Fabrizi d'Acquapendente on the embryos of mammals and on the chick. In the 17th century, biological studies received a further impulse. Apart from the chemiatric and iatromechanical conception of the organism (v. FISIOLOGIA), respectively the starting points of modern physiological chemistry and mechanics, b. benefited in this century both from new instruments that widened the field of investigation and from new organizations that made studies, research and experiments possible by providing scientists with the material and spiritual means suited to their task. The most important instrument was certainly the microscope, whose discovery wavers between Jansen, Fontana and Galilei. Other instruments useful for this kind of research were the thermometer, whose application to the animal organism is due to S. Santorio, the pulsologium (Galilei, Santorio), the hygrometer, the barometer, etc. Equally useful were the institutions of the scientific academies (of the Segreti, of the Lincei, of the Cimento, of the « Naturae Curiosorum », of France, the « Royal Society », etc.). The experimental method begins to put down firm roots, promoted by Italian thinkers (Campanella, Bruno, Telesio, etc.) and established with Descartes, Bacon and Galilei. Among the major biologists of this time are to be remembered F. Redi with his first systematic studies of parasitology, with the first denials of the spontaneous generation of insects, of the venom of vipers, etc.; M. Malpighi, the first student of general histology, discoverer of the blood capillaries, of the cells, of the blood corpuscles, of those of the spleen, etc. Important are his studies of comparative anatomy and of the incubated egg, which gave an impulse to further embryological research on the anatomy of plants. A. Vallisnieri occupied himself with the generation of insects (denying the spontaneous generation of gall insects) and described the anatomy of worms; D. Cestoni, discoverer, together with G. C. Bonomo, of the acarian origin of scabies, was a student of broader biological subjects and of natural phenomena (algae, fungi, molluscs, amphibians, bats, etc.). Among foreigners are to be remembered G. Bauhin, recognized as the first of the systematists for having made more current use of binomial nomenclature; J. Jung, J. Ray, to whom attempts at zoological classification are due; J. Pitton de Tournefort, an illustrious botanist. To G. Harvey is due the completion of the discovery of the circulation of the blood and studies on the generation of animals; to J. Swammerdam are due important anatomical studies on insects and on their generation; moreover Hooke carried out important microscopic observations on the cell, while A. Leeuwenhoek discovered the infusoria and devised special types of microscope. He also described the spermatozoa (which had already been seen by G. de Hamme), with which he gave support to the theory of preformationism, against that of epigenesis. The studies of comparative anatomy have, in the 17th century, an important development; they recall the names of G. Perrault, of E. Tyzson, of Grew (to whom the adoption of the term «comparative anatomy» is due) and of G. Blaes, author of the Anatomiae animalium. The 18th century is characterized in b. by profound disagreements foreshadowing more serious upheavals. B., as the «science of life», has profound repercussions on religious thought, and the 18th century is the age in which free thinkers, deists and Christians fought for their ideas; the age in which the so-called philosophy of nature develops, which gives a wholly characteristic direction to scientific thought, while the first symptoms of the question of the origin of species begin to take shape. Interesting, in b., is also the dissension between vitalists and mechanists (G. E. Stahl and F. Hoffmann). In this age, C. Linnaeus writes his Systema Naturae, in which plants and animals are classified. The system comprises classes, divided into orders which in turn comprise the genera, divided into species. The general plan of the system was established in 1735, the definitive edition is of 1758. Of each genus and each species he gave a definition in the denomination itself. G. L. Leclercq, count of Buffon, showed himself opposed to the concept of systematizing, which implies the idea of the fixity of species; he was the author of a powerful Natural History in which the first signs of Darwinian evolutionary theory are found. His ideas were examined by Erasmus Darwin, Charles's grandfather, who was to give them a very different development. Comparative anatomy boasts the names of Vicq d'Azyr, who occupied himself particularly with the correlation of organs, and of J. Hunter, anatomist, physiologist, surgeon, palaeontologist. To L. Spallanzani are due the establishment of experimental physiology, the denial of the spontaneous generation of the infusoria as well as important studies on digestion, respiration, etc. In embryology G. F. Wolff emerged, who gave this study a particular direction although he was much opposed by A. Haller, the great Swiss physiologist to whom the theory of irritability is due.

The 19th century is the age in which b. attains its greatest development and takes precisely this name, given to it by G. Treviranus. Comparative anatomy takes its definitive orientation with G. Cuvier and with the formulation of the fundamental principles given by S. Geoffroy-St-Hilaire, to whom the constitution of its organic plan is due. The greatest impulse of this science, in the 19th century, was due to G. Müller, Owen and Gegenbaur, though with different directions. Palaeontology is born as a study in its own right, of which R. Owen was one of the first exponents. In the same period the study of the origin of species takes shape. In opposition to the idea of discontinuous morphology, that of evolution, which had appeared with G. Lamarck, had the support of Geoffroy-St-Hilaire but the opposition of Cuvier, so that it seemed to decline. Taken up later by H. Spencer, the same concept (to which the name of evolution was given) received its greatest impulse with C. Darwin, who based natural selection on the struggle for existence. Darwin's idea was completed by Th. H. Huxley, who admitted the descent of man from animals. Among those who saw in this theory a weapon for combating religion was E. Haeckel, who nevertheless did not shrink from resorting to stratagems when the facts did not prove him right. To the principle of selection was later added that of C. von Naegeli (Progression-gesetz), to whom the concept of idioplasm is due, that of mutations (U. De Vries) and that of hologenesis of D. Rosa. Despite numerous oppositions (Flourence, Claude Bernard, Pasteur, Quatrefages, etc.) evolutionism continued, down to the present day, with varying fortunes.

Modernly linked to it are genetics and heredity, which in turn connect back to the first attempts of the hybridists of the 18th century, whose research reached its culmination with the discovery of G. Mendel (1865), preceded by that of Ch. Naumin (1861). The study of living matter had fundamental developments with the better knowledge of the cell considered as the basis of the constitution of the animal and plant organism (T. Schwann, Schleiden, Bizzozero, Remak, etc.). Generation had passionate scholars especially in the field of artificial fertilization, already begun by Spallanzani and repeated by O. Hertwig and T. Boveri. The theory of spontaneous generation received its final blow with the experiments of L. Pasteur, which also denied the spontaneous generation of microbes. A new field of action opened up for the study of embryology thanks to C. von Baer, who, preceded by Rusconi, elevated ontogeny to an autonomous discipline. Experimental embryology began with the experiment of Baer and Remak and continued with those of Huxley and Agassiz, which led to Haeckel's law (ontogenetic development recapitulates phylogenetic development), but true experimental embryology was established by G. Roux.

The great discovery of the existence of microbes, already intuited in past centuries and demonstrated by A. Bassi in 1835, followed by L. Pasteur and R. Koch, creators of microbiological science, greatly widened the field of biological studies, extending them to invisible animal and plant forms. Likewise physiology and paleontology benefit greatly from the progress of the auxiliary sciences and from the development of new concepts, especially in the field of physics and chemistry, as well as of microbiology, while anatomy evolved its investigations and its applications toward new directions (anthropology, constitutionalism, anatomy of the living, etc.).

Adalberto Pazzini