BIOLOGY. The biological sciences are those which deal with the phenomena of living things. They cover an enor mous field of scientific activity and as a whole are pretty clearly separated from the abiological sciences. Interest in bi ology leading to greater knowledge has vastly increased in the last fifty years, has led to numerous subdivisions of the science, and has made it impossible for a single mind to so completely grasp the entire subject as did Huxley. For this reason the single subject is now rarely recognized as a university department and courses of instruction which are de signed to give the student some general but accurate knowledge of the forms and activities of living things have not a prominent place in curricula. This is unfortunate, for environment brings man in contact with objects for biolog ical study and whatever his main in terest in life, he cannot neglect the in fluence of biological science upon that interest. Subjects such as psychology, sociology, and history are not generally considered as belonging to biology, but they really do; psychology being closely related to physiology, the phases of soci ology exhibited by beings other than man are closely interlinked with those exhibited by man, and history broadly considered is but the influence of envi ronmental conditions upon man. Biolog ical science, though holding a place of its own, has close relation with abiolog ical science which is recognized in phys ics and chemistry by the creation of departments of biophysics and biochem istry. The relation between physics and chemistry is accentuated in the physics and chemistry underlying and control ling the activities of living things, certain chemical and physical arrange ments of matter being found almost ex clusively in living matter. The methods of biological science are the same as in all other science, experiment holds the same foremost place, and the compara tive method is of great importance. Liv ing matter has certain characteristics which in their entirety distinguish it from all other forms of matter, but no single one of which is differential.
1. It never occurs in solution, but in insoluble units which are heterogeneous in composition. When these units are of sufficient size to be studied under the microscope, optical difference in refrac tion can be distinguished in the compo nent material, and this indication of dif ference is accentuated by coloring the material with selective dyes. The ma
terials in the unit have a certain orderly arrangement giving the conception of differentiated organs, and this is more evident in the higher animals and plants. Living things are known as organisms and organic has become almost synony mous with living. The units of living matter are called cells and these vary in form, structure, and size, some being so large that they can be seen with the un aided eye; others are too small to be seen with the highest power of the mi croscope. The living thing may be a single cell or in case of the higher ani mals and plants may be formed of great numbers of cells, those similar in char acter being combined in masses termed organs which have separate functions but which are co-ordinated with the ac tivity of the organism as a whole.
2. The chemical composition of living material is extraordinarily complex and we are still far from knowing completely its physicochemical structure. A large number of elements combined to form giant molecules termed proteins is a dis tinguishing feature. Knowledge of these proteins is obtained from the study of their split products, for they have not been formed synthetically. The smallest living unit must carry out a number of activities, and if we assume that each of these is due to a difference in the character of the material it is difficult in view of the large size of the molecules that they can all be contained in the unit. Recent investigations of the filter able viruses have shown the existence of living units which are not even visible with the ultra-microscope, and pass through filters which hold back large molecules. Knowledge of the chemical composition of living matter is obtained by the study not of living hut of dead protoplasm, and it is possible that living activity may be due not so much to chemical composition as to physico chemical intracellular structure. Liv ing material is generally known as pro toplasm, the word first being used by Purkinje, 1787-1869, to describe the material of the embryo. Water in large but variable amounts always enters into the composition of living matter and life is possible only in a fluid environ ment. Every living cell must be sur rounded by or in contact with water, for it is only in this way that substances necessary for its growth can be con veyed to it and products of waste re moved. Within the cell it plays an equally important part in making pos sible chemical changes.