The Principles of Biology, Volume 1 (of 2). Spencer Herbert

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СКАЧАТЬ the unlike, called Classification. First by observation of external characters; second by observation of internal characters; and third by observation of the phases of development; it is ascertained what organisms are most similar in all respects; what organisms otherwise unlike are like in important traits; what organisms though apparently unallied have common primordial characters. Whence there results such an arrangement of organisms, that if certain structural attributes of any one be given, its other structural attributes may be empirically predicted; and which prepares the way for that interpretation of their relations and genesis, which forms an important part of rational Biology.

      § 39. The second main division of Biology, above described as embracing the functional phenomena of organisms, is that which is in part signified by Physiology: the remainder being distinguishable as Objective Psychology. Both of these fall into subdivisions that may best be treated separately.

      That part of Physiology which is concerned with the molecular changes going on in organisms, is known as Organic Chemistry. An account of the modes in which the force generated in organisms by chemical change, is transformed into other forces, and made to work the various organs that carry on the functions of Life, comes under the head of Organic Physics. Psychology, which is mainly concerned with the adjustment of vital actions to actions in the environment (in contrast with Physiology, which is mainly concerned with vital actions apart from actions in the environment) consists of two quite distinct portions. Objective Psychology deals with those functions of the nervo-muscular apparatus by which such organisms as possess it are enabled to adjust inner to outer relations; and includes also the study of the same functions as externally manifested in conduct. Subjective Psychology deals with the sensations, perceptions, ideas, emotions, and volitions that are the direct or indirect concomitants of this visible adjustment of inner to outer relations. Consciousness under its different modes and forms, being a subject-matter radically distinct in nature from the subject-matter of Biology in general; and the method of self-analysis, by which alone the laws of dependence among changes of consciousness can be found, being a method unparalleled by anything in the rest of Biology; we are obliged to regard Subjective Psychology as a separate study. And since it would be very inconvenient wholly to dissociate Objective Psychology from Subjective Psychology, we are practically compelled to deal with the two as forming an independent science.

      Obviously, the functional phenomena presented in successions of organisms, similarly divide into physiological and psychological. Under the physiological come the modifications of bodily actions that arise in the course of generations, as concomitants of structural modifications; and these may be modifications, qualitative or quantitative, in the molecular changes classed as chemical, or in the organic actions classed as physical, or in both. Under the psychological come the qualitative and quantitative modifications of instincts, feelings, conceptions, and mental processes in general, which occur in creatures having more or less intelligence, when certain of their conditions are changed. This, like the preceding department of Psychology, has in the abstract two different aspects – the objective and the subjective. Practically, however, the objective, which deals with these mental modifications as exhibited in the changing habits and abilities of successive generations of creatures, is the only one admitting of investigation; since the corresponding alterations in consciousness cannot be immediately known to any but the subjects of them. Evidently, convenience requires us to join this part of Psychology along with the other parts as components of a distinct sub-science.

      Light is thrown on functions, as well as on structures, by comparing organisms of different kinds. Comparative Physiology and Comparative Psychology, are the names given to those collections of facts respecting the homologies and analogies, bodily and mental, disclosed by this kind of inquiry. These classified observations concerning likenesses and differences of functions, are helpers to interpret functions in their essential natures and relations. Hence Comparative Physiology and Comparative Psychology are names of methods rather than names of true subdivisions of Biology.

      Here, however, as before, comparison of special truths, besides facilitating their interpretation, brings to light certain general truths. Contrasting functions bodily and mental as exhibited in various kinds of organisms, shows that there exists, more or less extensively, a community of processes and methods. Hence result two groups of propositions constituting General Physiology and General Psychology.

      § 40. In these divisions and subdivisions of the first two great departments of Biology, facts of Structure are considered separately from facts of Function, so far as separate treatment of them is possible. The third great department of Biology deals with them in their necessary connexions. It comprehends the determination of functions by structures, and the determination of structures by functions.

      As displayed in individual organisms, the effects of structures on functions are to be studied, not only in the broad fact that the general kind of life an organism leads is necessitated by the main characters of its organization, but in the more special and less conspicuous fact, that between members of the same species, minor differences of structure lead to minor differences of power to perform certain actions, and of tendencies to perform such actions. Conversely, under the reactions of functions on structures in individual organisms, come the facts showing that functions, when fulfilled to their normal extents, maintain integrity of structure in their respective organs; and that within certain limits increases of functions are followed by such structural changes in their respective organs, as enable them to discharge better their extra functions.

      Inquiry into the influence of structure on function as seen in successions of organisms, introduces us to such phenomena as Mr. Darwin's Origin of Species deals with. In this category come all proofs of the general truth, that when an individual is enabled by a certain structural peculiarity to perform better than others of its species some advantageous action; and when it bequeaths more or less of its structural peculiarity to descendants, among whom those which have it most markedly are best able to thrive and propagate; there arises a visibly modified type of structure, having a more or less distinct function. In the correlative class of facts (by some asserted and by others denied), which come under the category of reactions of function on structure as exhibited in successions of organisms, are to be placed all those modifications of structure which arise in races, when changes of conditions entail changes in the balance of their functions – when altered function externally necessitated, produces altered structure, and continues doing this through successive generations.

      § 41. The fourth great division of Biology, comprehending the phenomena of Genesis, may be conveniently separated into three subdivisions.

      Under the first, comes a description of all the special modes whereby the multiplication of organisms is carried on; which modes range themselves under the two chief heads of sexual and asexual. An account of Sexual Multiplication includes the various processes by which germs and ova are fertilized, and by which, after fertilization, they are furnished with the materials, and maintained in the conditions, needful for their development. An account of Asexual Multiplication includes the various processes by which, from the same fertilized germ or ovum, there are produced many organisms partially or totally independent of one another.

      The second of these subdivisions deals with the phenomena of Genesis in the abstract. It takes for its subject-matter such general questions as – What is the end subserved by the union of sperm-cell and germ-cell? Why cannot all multiplication be carried on after the asexual method? What are the laws of hereditary transmission? What are the causes of variation?

      The third subdivision is devoted to still more abstract aspects of the subject. Recognizing the general facts of multiplication, without reference to their modes or immediate causes, it concerns itself simply with the different rates of multiplication in different kinds of organisms and different individuals of the same kind. Generalizing the numerous contrasts and variations of fertility, it seeks a rationale of them in their relations to other organic phenomena.

      § 42. Such appears to be the natural arrangement of divisions and subdivisions which Biology presents. It is, however, a classification of the parts of the science when fully СКАЧАТЬ