Biological function

“ Hence the invariable character of the germ-cells. In bone-formation, it is clearly shown that special structure begins very early,—in the cell, namely; but it is preserved only where it is aided by the necessary action and reaction. Autonomic in itself, life submits itself to the general laws of evolution. [67] As the direction of motion is determined for whole groups of cells by the direction of the motion of the protoplasm in the single cells, so organic function is determined by the grouping of the irritable, contractile, sensible cells. ”

“ For if an organism A, has, by any peculiar habit or condition of life, been modified into the form A′, it follows that all the functions of A′, reproductive function included, must be in some degree different from the functions of A. An organism being a combination of rhythmically-acting parts in moving equilibrium, the action and structure of any one part cannot be altered without causing alterations of action and structure in all the rest ”

“ The strands of its nerve fibers and its groups of cells keep the various organs of the body properly coördinated, whereas in the second place, through the sensitive structures at the surface of the body, they receive the impressions from the outside world and so enable the organism to relate itself properly to its environment. The last organic system differs from the other seven in that the performance of its task is of far less importance to the individual than it is to the race as a whole. It is the reproductive system, with a function that must be always biologically supreme. ”

“ Thus everything we can see in animals is adaptation, whether of to-day, or of yesterday, or of ages long gone by; every kind of cell, whether glandular, muscular, nervous, epidermic, or skeletal, is adapted to absolutely definite and specific functions, and every organ which is composed of these different kinds of cells contains them in the proper proportions, and in the particular arrangement which best serves the function of the organ ”

“ A large number of experiments on the effects produced by changes in the external conditions of life have been made. To this class of investigations belong studies on the regulation of form and function in organisms (Loeb, Child) , the effects produced by altering mechanical conditions of growth, by [Pg 441] changing the chemical environment, etc. There is some internal mechanism in living matter that is influenced by changes in external conditions, and the study of the regulation of the internal processes that produce form and structure have given rise to a variety of interesting problems. ”

“ But it is not equally manifest that, on this hypothesis, alterations of structure caused by alterations of function must be transmitted to offspring. It is not obvious that change in the form of a part, caused by changed action, involves such change in the physiological units throughout the organism that these, when groups of them are thrown off in the shape of reproductive centres, will unfold into organisms that have this part similarly changed in form. ”

“ Now, the one characteristic of the tissue which most strikes our attention is its degeneracy, and this degeneracy must exert its influence on the organisms which depend upon it for existence, so that in the thus derived organisms we have the germ vitality and function, plus a certain amount of degenerate tissue characteristic. ”

“ Embryology might almost be termed the science of organic differentiation. Now all that you do, as practising physicians, is to deal with differentiated organs and tissues. You deal with a function, normal or diseased, which is rendered possible by the differentiation of cells. You deal with pathological states, every one of which has its special differentiation. Every phenomenon which you encounter in your professional work is conditioned by the differentiation of the organic living substance. ”

“ Everywhere the peculiar form of the organism and its structures, internal and external, is directly related to the special physiological functions which the organism or organ has to execute. This intimate connection of structure and function, or of the instrument and the work done by it, is seen in the science of evolution and all its parts. Hence the story of the evolution of structures, which is our immediate concern, is also the history of the development of functions; and this holds good of the human organism as of any other. ”

“ It can readily be seen that specific intensity of metabolism, or of reactivity, and variation in constitutional size of cells may be such conditions. Others no doubt exist, of which sex may be one. The essential thing to recognize is that the heritable and segregable factors, being conditions of the germ cells at the start, can never be anything less than factors of the entire organism at all stages.
Our conclusion is that the theory of individual development must more and more come to be regarded as a branch of physiology proper. ”

“ All animals therefore, I contend, have a similar cause of their organization, originating from a single living filament, endued indeed with different kinds of irritabilities and sensibilities, or of animal appetencies; which exist in every gland, and in every moving organ of the body, and are as essential to living organization as chemical affinities are to certain combinations of inanimate matter. ”

“ And, on the other hand, every individual organism, from the Amœba up to the most complex vertebrate, is, in its structure, its form, its functions, a stupendous marvel of adaptation to its end and of co-ordination of the parts to the whole, and of the whole and its parts to the functions of the organism, the functions of nutrition, self-maintenance, reproduction, maintenance of the species, and so on. ”

“ In the lowest organism all parts are competent to perform all functions, and one and the same portion of protoplasm may successfully take on the function of feeding, moving, or reproducing apparatus. In the highest, on the contrary, a great number of parts combine to perform each function, each part doing its allotted share of the work with great accuracy and efficiency, but being useless for any other purpose. ”

“ If the study of biology will give us a better understanding of our own bodies and their care, then it certainly is of use to us. That phase of biology known as physiology deals with the uses of the parts of a plant or animal; human physiology and hygiene deal with the uses and care of the parts of the human animal. ”

“ It is form particularly which can be said to occupy the very centre of biological interest; at least it furnishes the foundation of all biology. Therefore we shall begin our scientific studies with a full and thorough analysis of form. The science of living forms, later on, will afford us a key to study metabolism proper with the greatest advantage for our philosophical aims, and therefore the physiology of what is usually called the vegetative functions will be to us a sort of appendix to our chapters on form ”

“ We turn thus from the RESULTS of the selection of favorable variations to the biological PROCESSES by which organisms become accommodated to their conditions of life.
At once the old questions arise. Are these processes fundamentally peculiar to the life of organisms? Does the capacity of the organism thus to adjust itself to its environment involve factors not found in the operations of inorganic nature? Our answers will be determined essentially by the nature of our interest in the organism—whether we regard its existence as the END or merely an incidental EFFECT of its activities. ”

“ If the law of the animal cell, and of the animal organism, which is built up of such cells, is like that of the vegetable, we might expect that we should treat all morbid conditions of any of the vital unities belonging to an animal in the same way, by increasing, diminishing, or changing its natural food or stimuli. ”

“ If we clearly recognize that the physical basis of life is the same in both plant and animal, and that it is through disturbance, primarily, of the protoplasmic functions that the functions of the organism as a whole are disordered, then from this and what has already been stated it becomes evident that the pathology of plants and animals is the same, chiefly involving greater degrees of complexity in the latter, and that we must apply the same principles for the recognition of disease in each case. ”

“ This is the first great attempt to construct a scientific, physiological theory of the development of organic life and to prove that the physiological laws and the chemical and physical forces that rule in nature to-day must also have been at work in the world of yesterday. ”

“ They certainly will not be prepared to go as far as I now propose to go, and say that the thinking organism is the production of thought—the very antithesis, you will agree, of the other position, but which is vital to the understanding of the unfolding of the powers of consciousness through matter. It is recognised in ordinary biology that the function appears before the organ. There I am on safe scientific ground. It is recognised that the exercise of the function gradually builds up the organ. All the researches into the simpler forms of organisms go to prove that. ”

“ Man and the neighbouring species, which are the particular object of our researches, enjoy then evidently, all the vital properties, some of which belong to organic life, the others to animal life. 1st. Organic sensibility and insensible contractility have all the phenomena of the capillary circulation, of secretion, of absorption, exhalation, nutrition, &c. evidently dependant upon them in a state of health. In treating, therefore, of these functions, we must always ascend to these properties. ”

“ All the physiological activities of animals and plants—assimilation, secretion, excretion, motion, generation—are the expression of the activities of the cells considered as physiological units. Each individual, among the higher animals and plants, is a synthesis of millions of subordinate individualities. ”

“ It is sufficient for our purposes to know that they may have set up certain internal stimuli which may modify the behavior of the organism in which they reside, and that the “physiological state” of the organism at the time of external or internal stimulation will condition the response. This physiological condition may be dependent on the general metabolic equilibrium of the animal, or on the extent of previous stimulation by means of the same or different agents. Thus the organism may not always react in the same way to the same stimulus. ”

“ Experimental Biology and General Physiology are one and the same science, in method as well as content, since both aim at explaining life from the physico-chemical constitution of living matter. The series of monographs on Experimental Biology will therefore include the field of traditional General Physiology. ”

“ If the famous suggestion, that all animal and vegetable life results from a single vital germ, and that all the different animals and plants now existent were developed by a natural process of evolution from that germ, were a demonstrated truth, we should still be able to point to the evidence of intelligence displayed in the measured and progressive development, in those exquisite forms so different from what blind chance could produce, and in the manifest adaptation of surrounding circumstances to the living creature, and of the living creature to surrounding circumstances. ”

“ Fundamental Vital Activities as Located in Cells.—We are now in position to ask whether our knowledge of cells has aided us in finding an explanation of the fundamental vital actions to which, as we have seen, life processes are to be reduced. The four properties of irritability, contractibility, assimilation, and reproduction, belong to these vital units—the cells, and it is these properties which we are trying to trace to their source as a foundation of vital activity. ”

“ For the first time in the history of science, physiologists are now in the position to say that they have arrived at clear and distinct, though by no means complete, conceptions of the manner in which the great functions of assimilation, respiration, secretion, distribution of nutriment, removal of waste products, motion, sensation, and reproduction are performed ”

“ The proposed definition of organic life supplies an answer. If organic life be the co-ordination of actions, then an organism may be primarily divided into parts whose actions are co-ordinated, and parts which co-ordinate them—organs which are made to work in concert, and the apparatus which makes them so work—or, in other words, the assimilative, vascular, excretory, and muscular systems on the one hand, and the nervous system on the other. The justness of this classification will become further apparent, when it is remembered that by the nervous system alone is the individuality established. ”

“ The vital activities taking place in the bodies of higher animals are too complicated and too intricately mixed to admit of clear analysis, and, long ago, physiologists learned that the quest for explanations of living activities lay along the line of investigating them in their most rudimentary expression. The practical recognition of this is seen in our recent text-books upon human physiology, which commonly begin with discussions of the life of these simplest organisms. ”

“ In this way originates the first of the vital functions which becomes established in the simplest organism, i.e., nutrition. The environing containable fluids are, then, for the living body of very great simplicity, a veritable chyle entirely prepared by nature.
“Mutilation cannot operate without gradually increasing the consistence of the parts contained within the minute new organism and without extending its dimensions. Hence soon arose the second of the vital functions, growth or internal development.” ”