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, b. means: the study of the different forms assumed by organic life, of the different conditions and laws governing its existence, and of the causes determining its activity. With this original concept, the term is given a vitalistic imprint, insofar as the ensemble of phenomena to which it refers is subject to forces not found in the inorganic world. Even today, very many biologists are convinced that, although the organic and organized world is subject to the laws of physics and chemistry, it is also governed by forces unknown to the physical world; others, however, hold that “vital” forces are obscure and apparently metaphysical, but that with the progress of science they too will be evaluated according to the same laws as the physical world. This materialistic current concerning life finds one of its earliest advocates in Lamarck.
The term b. may be used in the broad sense, according to the definition given above, or in the strict sense, that is, as the study of the habits and way of life (ecology) of the various animals and plants. By the term general b. is meant a discipline that considers all vital phenomena synthetically, so as to discern the general laws governing them. If we refer to one of the most modern treatises on general b., for example that of Cotronei, we see that the subject is divided into the following parts and chapters: Part 1 deals with “biological organization,” with chapters on the limits of the biological sciences, mechanism and vitalism, the origin of life, the differences between animals and plants, the colloidal structure of protoplasm, the cell in general, the chemical constitution of organisms, the vital activities of cells, the reproduction of cells and organisms, embryonic development, the structure of tissues, growth, old age, and death. Part 2 deals with “heredity and biological environments”; Part 3 with “morphology,” that is, comparatively with the anatomy of living beings (in this book restricted to vertebrates for didactic reasons), so as to comprehend the significance of structures.
The field of b. is extremely vast, and various biological disciplines have consequently arisen. First of all, one may distinguish an animal b., concerned with the fauna, and a plant b., concerned with the flora, although the division between the two kingdoms is not clear-cut because of the presence of living beings representing intermediate conditions. Organisms may be studied from different points of view: their structure, their activity or function, and their abnormalities. We thus have three broad groups of disciplines, which we designate by the terms general morphology, general physiology, and general pathology. Morphology includes cytology, which studies the cell; embryology, which studies the stages of development; histology, which considers the association of cells constituting the tissues of multicellular organisms; organology, which studies organs; and anatomy, which studies the various parts of organisms. Particular disciplines are comparative anatomy, which, through comparison of structure in the various animal species, investigates the morphological significance of the various structures, and human anatomy, which deals exclusively with the structure of man. Physiology includes biophysics and biochemistry, which deal respectively with the physical and chemical aspects of 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 divided into plant, animal, and human pathology. Human pathology is divided into medical and surgical pathology. One aspect of pathology is studied by general pathology, which deals with the general 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, predictions concerning their outcome, and the outcome itself. Disciplines connected with it are bacteriology, which studies the life of pathogenic and nonpathogenic microorganisms (which do or do not cause diseases); parasitology, which deals with organisms living on other organisms and causing them harm and lesions; and teratology, which investigates monstrosities, elucidating their embryological mechanism. Other branches of b. are zoological and botanical systematics, which deal with the classification of animals and plants into related groups; genetics, which deals with the transmission of hereditary characteristics and their behavior in successive generations; ethology, which studies organisms in their environment (biogeography is a branch of it and studies the factors governing the geographical distribution of organisms); and oceanography, hydrobiology, and limnology, which study respectively life in the seas, in fresh waters in general, and in lakes in particular. Psychology should also be included among the biological sciences, at least in some of its aspects, specifically as experimental psychology and comparative psychology, which study the behavior of animals.
A series of biological disciplines is eminently practical in character: agricultural biology, arboriculture or forestry, horticulture, floriculture, plant pathology, agricultural bacteriology, agricultural entomology, hydrobiology applied to fishing, animal husbandry, aviculture, sericulture, etc.
Finally, we may bring together all the biological disciplines concerning the human species, such as anthropology, which deals with the various human races; human paleontology, which deals with fossil humans; anthropometry; eugenics; human heredity; ethnology; ethnography; sociology; constitutional pathology; human psychology; and finally the entire group of medical sciences.
BIBLI: T. Peterf, Methodik der wissenschaftlichen Biologie, Berlin 1928; G. Chiarugi, Trattato di embryologia, 5 vols., Milan 1929–40; V. Puntoni, Manuale di microbiologia, Rome 1935; G. Negri, G. Gola and C. Capelletti, Trattato di botanica, Turin 1936; G. Cotronei, B. e zoologia generale, Rome 1942; J. Needham, Byochemistry and morphogenesis, Cambridge 1942; C. Jucci, Introduzione allo studio della genetica, Milan 1944; G. Montalenti, Problemi della b. della riproduzione, Verona 1945; P. Rondoni, Biochimica, Turin 1945; G. Levi, Istologia, there 1947. Alberto Stefanelli
HISTORY OF B. - The study of b. began in the Italic schools in the sixth century B.C. From that period dates the first outline 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 accessible to human study.
This is how Alcmaeon of Croton, the first of the great «physiologists» (students of nature), expressed himself. With him anatomical investigation began, together with the attempt to explain physiological phenomena. The first biological laws were formulated through the concept of isonomia, according to which the organism is considered to be composed of various pairs of opposites, from whose proper proportion the normal state emerges, whereas disease (monarchia) originates from disproportion. Contemporaneous with it, and involved in a dispute over priority, is the principle of enantiosis, devised by Pythagoras. While the latter, however, is predominantly cosmic in character, the Alcmaeonian principle is more directly biological. Empedocles of Agrigentum (sixth–fifth century B.C.) is responsible for specifying isonomia through the recognition of four elements (water, air, earth, and fire), which he calls «the roots of all things». The animal organism would likewise have this constitution, and its various functions would be carried out by virtue of the magical law of similarity. Philolaus of Tarentum is responsible for 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, and yellow bile). This theory established solid foundations in biological thought and prevailed until the last century, while today it is re-emerging in the theory of hormones. In it too, health consists in perfect proportion, whereas the corruption or excess of one of them constitutes disease. Aristotle is responsible for expanding the study of b. and establishing a doctrinal system; for this reason he was called the father of this science. He made the first attempt at classifying living forms, in which these, by degrees, proceeding from plants through mollusks, arthropods, crustaceans, reptiles, and mammals, reach man. He was the founder of comparative anatomy and, it is said, the first to produce anatomical drawings. He recognized the four Empedoclean elements, to which he added a «fifth essence». To him, therefore, is owed the principle of combining science and philosophy within the same method of inquiry, which was later to be replaced by the inductive method by Galileo; likewise, the establishment of the doctrine of spontaneous generation, a principle that was subsequently distorted and exaggerated (v. GENERAZIONE SPONTANZA).
Vegetable b. had its first scholar in Theophrastus of Ephesus (fourth century B.C.), a pupil of Aristotle. He is responsible for a book on the History and one on the Causes of Plants. The study of b. reached its apogee, as regards anatomy and physiology, in the Alexandrian schools (late fourth century B.C.), especially through the work of Herophilus and Erasistratus (v. ANATOMY). Other scholars worthy of note were, although earlier and therefore less advanced, Diosippus of Cos and Praxagoras of Cos. B. occupies an important place in Pliny’s Natural History (A.D. 23–79). In it, for its period, botany, zoology, and medicine are treated comprehensively, together with mineralogy, geography, and so forth. This work has the merit of collecting everything known at that time. His contemporary was Pedanius Dioscorides of Anazarbus, author of a vast work on plants and animals, which he considered, however, solely from the therapeutic standpoint. Nearly all later authors who dealt with the same subject (Pseudo-Apuleius, Macer Floridus, etc.) took their inspiration from this work. Many Fathers of the Church also concerned themselves with b., in order to glorify divine creation, in their homilies and in the exaemeron (s. Ambrose, s. Augustine, Nemesius, etc.). Among these, s. Basil is important for the particular interest he devoted to scientific studies. Also noteworthy are s. Hildegard, author of the celebrated Physica, and s. Isidore of Seville, author of the Etymologiae; nor should one forget the Speculum Naturale of the Dominican Vincent of Beauvais, which is highly interesting because it gives us a picture of the knowledge available in this field. More important, however, as an early expression of freedom of scientific thought, is the work of s. Albert the Great, which also extended into the biological field, since he had the audacity to set his own thought against the Plinian assertions generally accepted in a dogmatic manner. Another scholar of b., although he directed his study of plants toward their pharmaceutical uses, was Simone Cordo, known as Simone Genovese, chaplain to Boniface VIII and author of a Clavis sanationis. With the establishment of Renaissance thought, b. too received a considerable impulse. The renewed study of nature prompted scientists and philosophers to attempt to uncover its mysteries, giving rise to naturalistic philosophy and so-called natural magic, which should be regarded as a forerunner of the experimental method. Leonardo da Vinci deserves particular attention for his anatomical studies and his observations in physiology and botany. He studied the growth of plants, discovered the law governing the emergence of leaves on branches, observed the concentric rings of the stem, by which the age of plants can be determined, intuited the existence of circulation in plants, experimented on the action of toxic substances on plant development, and obtained alcoholic solutions of chlorophyll. In 1513 Leo X established the first chair of simples, to which Giuliano da Foligno was appointed. At the same time, a first herb garden was established in the Belvedere garden. In keeping with the spirit of the Renaissance, the ancient works were also revised in b.: important for this purpose was Niccolò Leoniceno’s De erroribus Plinii et aliorum etc. The first botanical gardens were established, besides the one in Rome; the most celebrated were those of Pisa (1544) and Padua (1545). Venice is said to have had one as early as 1533. Eminent scholars were L. Ghini, F. Bonafede, and Anguillara (L. Squaleno) for vegetable b., systematics, and the identification of new species; P. A. Mattioli, C. Durante, F. Calzolari, P. Castelli, B. Maranta, and F. Imperato for the same studies and for the pharmacological application of plants. An attempt at classification was made (M. Lobel–A. Cesalpino); the latter was responsible for extremely important observations throughout the field of vegetable b. A particular impulse to knowledge of the flora of the countries of the new continent was provided by P. Alpino, who accurately described that of Egypt, while among foreign scholars J. Ruel (1479–1589) and C. de Lécluse (1526–1609) should be remembered.
In animal b., the discovery of the circulation of the blood by A. Cesalpino and R. Colombo was of the greatest importance. The humoral theory, however, remained unchanged (although attempts were made to modify it), as did the attribution of the functions of the various organs to the virtutes. Of interest for zoology were the studies of U. Aldovrandi, while straddling the sixteenth and seventeenth centuries stands the surgeon M. A. Severino (1580–1656), a student of comparative anatomy and a convinced proponent of the uniformity of the innermost structure of all organized beings, which, in his view, differed from one another only in outward appearance. He extended his conclusions to the plant kingdom as well. His Zootomia democratica must be regarded as the first treatise on comparative anatomy. The study of embryology began during this period with the research of G. Fabrizi d’Acquapendente on mammalian embryos and the chick. In the seventeenth century, the study of b. received a further impetus. Apart from the chimiatric and iatromechanical conception of the organism (v. FISIOLOGIA), respectively the beginnings of modern chemistry and physiological mechanics, b. benefited during this century both from new instruments that broadened the field of investigation and from new organizations that made studies, research, and experiments possible by providing scientists with the material and intellectual means suited to their task. The most important instrument was certainly the microscope, whose discovery is variously attributed to 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. The institutions of the scientific academies were likewise of the greatest utility (the Accademia dei Segreti, the Lincei, the Cimento, the « Naturae Curiosorum », the Académie de France, the « Royal Society », etc.). The experimental method began to put down firm roots, promoted by Italian thinkers (Campanella, Bruno, Telesio, etc.) and established by Descartes, Bacon, and Galilei. Among the leading biologists of this period, mention should be made of F. Redi, with his first systematic studies of parasitology and his first denials of the spontaneous generation of insects and of the venom of vipers, etc.; M. Malpighi, the first student of general histology, discoverer of the blood capillaries, cells, blood corpuscles, splenic corpuscles, etc. His studies of comparative anatomy and of the incubated egg were important and stimulated further embryological research into the anatomy of plants. A. Vallisnieri concerned himself with the generation of insects (denying the spontaneous generation of gall insects) and described the anatomy of worms; D. Cestoni, who, together with G. C. Bonomo, discovered the acarid origin of scabies, studied broader subjects in b. and natural phenomena (algae, fungi, mollusks, amphibians, bats, etc.). Among foreign scholars, mention should be made of G. Bauhin, recognized as the first of the systematists for having made more consistent use of binomial nomenclature; J. Jung and J. Ray, to whom attempts at zoological classification are owed; and J. Pitton de Tournefort, an illustrious botanist. G. Harvey completed the discovery of the circulation of the blood and conducted studies on the generation of animals; J. Swammerdam carried out important anatomical studies of insects and their generation; Hooke made important microscopic observations of 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), thereby lending support to the theory of preformation against that of epigenesis. Studies of comparative anatomy underwent important development in the seventeenth century; they are associated with the names of G. Perrault, E. Tyzson, Grew (to whom the adoption of the term «comparative anatomy» is due), and G. Blaes, author of the Anatomiae animalium. The eighteenth century in b. was characterized by profound disagreements foreshadowing more serious upheavals. B., as the «science of life», had profound repercussions on religious thought, and the eighteenth century was the age in which freethinkers, deists, and Christians fought for their ideas; it was the age in which the so-called philosophy of nature developed, giving scientific thought a wholly distinctive direction, while the first symptoms of the question of the origin of species began to emerge. Also of interest in b. was the disagreement between vitalists and mechanists (G. E. Stahl and F. Hoffmann). During this period, C. Linnaeus wrote his Systema Naturae, in which plants and animals were classified. The system comprised classes, divided into orders, which in turn comprised genera, divided into species. The general plan of the system was established in 1735, while the definitive edition dates from 1758. He gave each genus and each species a definition within the designation itself. Opposed to the concept of systematization, which implied the idea of the fixity of species, was G. L. Leclercq, Comte de Buffon, author of a monumental Natural History in which the first signs of the theory of Darwinian evolution are found. His ideas were examined by Erasmus Darwin, Carlo’s grandfather, who was to give them a very different development. Comparative anatomy can claim the names of Vicq d’Azyr, who concerned himself particularly with the correlation of organs, and J. Hunter, anatomist, physiologist, surgeon, and paleontologist. L. Spallanzani is credited with establishing experimental physiology, denying the spontaneous generation of infusoria, and conducting important studies on digestion, respiration, etc. In embryology, G. F. Wolff emerged; he gave this field a particular direction, although he was strongly opposed by A. Haller, the eminent Swiss physiologist to whom the theory of irritability is due.
The nineteenth century was the period in which b. attained its greatest development and acquired the very name given to it by G. Treviranus. Comparative anatomy assumed its definitive orientation with G. Cuvier and with the formulation of the fundamental principles advanced by S. Geoffroy-St-Hilaire, to whom the establishment of its organic plan is due. The greatest impetus to this science in the nineteenth century came from G. Müller, Owen, and Gegenbaur, although their approaches differed. Paleontology arose as an independent field of study, with R. Owen as one of its first exponents. During the same period, the study of the origin of species began to take shape. In opposition to the idea of discontinuous morphology, the idea of evolution, which emerged with G. Lamarck, received the support of Geoffroy-St-Hilaire but met with Cuvier’s opposition, and thus seemed to decline. Later taken up again by H. Spencer, the same concept (to which the name evolution was given) received its greatest impetus from C. Darwin, who based natural selection on the struggle for existence. Darwin’s idea was completed by Th. H. Huxley, who accepted the descent of human beings from animals. Among those who saw in this theory a weapon with which to combat religion was E. Haeckel, who nevertheless did not hesitate to resort to stratagems when the facts did not support him. The principle of selection was later supplemented by that of C. von Naegeli (Progression-gesetz), to whom the concept of idioplasm is due, by the concept of mutations (U. De Vries), and by D. Rosa’s concept of hologenesis. Despite numerous oppositions (Flourence, Claude Bernard, Pasteur, Quatrefages, etc.), evolutionism continued, with varying fortunes, down to the present day.
Modernly, genetics and heredity are connected with it, and these in turn are related to the first attempts of the hybridists of the eighteenth century; their researches reached their culmination with the discovery of G. Mendel (1865), preceded by that of Ch. Naumin (1861). The study of living matter underwent fundamental developments through a better knowledge of the cell, considered as the basis of the constitution of the animal and vegetable organism (T. Schwann, Schleiden, Bizzozero, Remak, etc.). Generation had passionate investigators, especially in the field of artificial fertilization, already initiated by Spallanzani and repeated by O. Hertwig and T. Boveri. The theory of spontaneous generation received its final blow from the experiments of L. Pasteur, which also disproved the spontaneous generation of microbes. A new field of activity was opened for the study of embryology through the work of C. von Baer, who, preceded by Rusconi, raised ontogeny to the status of an autonomous discipline. Experimental embryology began with the experiments 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 the science of microbiology, greatly expanded the field of biological studies, extending them to invisible animal and vegetable forms. Physiology and paleontology likewise benefited greatly from the progress of the auxiliary sciences and from the development of new concepts, especially in the fields of physics and chemistry, as well as microbiology, while anatomy directed its investigations and applications along new paths (anthropology, constitutionalism, anatomy of the living, etc.).