Biology and Its Makers / With Portraits and Other Illustrations

by William A. Locy

With the advantage of the new appliances and the new methods, the old problems of anatomy are being worked over on a higher level of requirement. Still, it is doubtful whether even the old problems will be solved in more than a relative way. It is characteristic of the progress of research that as one proceeds the horizon broadens and new questions spring up in the pathway of the investigator. He does not solve the problems he sets out to solve, but opens a lot of new ones. This is one of the features of scientific research that make its votaries characteristically optimistic.

Experimental Work.—Among the recent influences tending to advance biology, none is more important than the application of experiments to biological studies. The experimental method is in reality applicable to diverse fields of biological research, and its extensive use at present indicates a movement in the right direction; that is, a growing interest in the study of processes. One of the earliest problems of the biologist is to investigate the architecture of living beings; then there arise questions as to the processes that occur within the organism, and the study of processes involves the employment of experiments. In the pursuit of physiology experiments have been in use since the time of Harvey, but even in that science, where they are indispensable, experiments did not become comparative until the nineteenth century. It now appears that various forms of experiment give also a better insight into the structure of organisms, and the practice of applying experiments to structural studies has given rise to the new department of experimental morphology.

For the purpose of indicating some of the directions in which biology has been furthered by the experimental method of investigation, we designate the fields of heredity and evolution, changes in the environment of organisms, studies on fertilization and on animal behavior.

The recognition that both heredity and the process of evolution can be subjected to experimental tests was a revelation. Darwin and the early evolutionists thought the evolutionary changes too slow to be appreciated, but now we know that many of the changes can be investigated by experiment. Numerous experiments on heredity in poultry (Davenport), in rats, in rabbits, and in guinea-pigs (Castle) have been carried out—experiments that test the laws of ancestral inheritance and throw great light upon the questions introduced by the investigations of Mendel and De Vries. The investigations of De Vries on the evolution of plant-life occupy a notable position among the experimental studies.

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 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. The regeneration of lost parts and regeneration after intentionally-imposed injury has received much attention (Morgan). Marine animals are especially amenable to manipulations of this nature, as well as to alterations in their surroundings, on account of the ease in altering the chemical environment in which they live. The latter may be accomplished by dissolving harmless chemical salts in the sea-water, and observing the changes produced by the alterations of the surrounding conditions. By this means Herbst and others have produced very interesting results.

In the field of artificial fertilization, free swimming larvæ have been raised from eggs artificially fertilized by changes in osmotic pressure, and also by treating them with both organic and inorganic acids; and these studies have greatly altered opinion regarding the nature of fertilization, and of certain other phenomena of development.

Animal Behavior.—The study of animal behavior (Jennings) is a very characteristic activity of the present, in which certain psychological processes are investigated. These investigations have given rise to a distinct line of research participated in by psychologists and biologists. The study of the way in which animals will react toward light of different colors, to variations in the intensity of light, to alterations in temperature, and to various other forms of stimuli are yielding very important results, that enable investigators to look beneath the surface and to make important deductions regarding the nature of psychological processes.

A line closely allied to experimentation is the application of statistics to biological processes, such as those of growth, stature, the law of ancestral inheritance, the statistical study of variations in spines, markings on shells, etc., etc., (Galton, Pearson, Davenport).

Other branches of biology that have been greatly developed by the experimental method are those of bacteriology and physiological chemistry. The advances in the latter have greatly widened the horizon of our view regarding the nature of vital activities, and they compose one of the leading features of current biological investigation.

Some Tendencies in Anatomical Studies. Cell-Lineage.—While experimental work occupies the center of the stage, at the same time great improvements in morphological studies are evident. It will be only possible, however, to indicate in a general way the direction in which investigations are moving. We note, first, as in a previous paragraph, that the improvement in morphology is generic as well as specific. Anatomical analysis is being carried to its limits in a number of directions. The investigations that are connected with the study of cells afford a conspicuous illustration of this fact. Studies in cell-lineage have led to an exact determination of cell-succession in the development of certain animals, and such studies are still in progress. Great progress also has been made in the study of physical structure of living matter. The tracing of cell-lineage is a feat of remarkably accurate and patient work. But, however much this may command our admiration, it has been surpassed (as related in Chapter XI) by investigations regarding the organization of the egg and the analysis of chromosomes. Boveri, Conklin, Wilson, and others have shown that there are recognizable areas within the protoplasm of the egg that have a definite historical relationship to certain structures in process of development. This is the basis upon which rests the doctrine of pre-localization of tissue-forming substances within the protoplasm of the egg.