Aristotle. -A reaction set in against the materialistic conceptions of Democritus and others. Philosophy came to be dominated by Socrates, who was interested in ethics, and by Plato, who found true reality in the world of abstract thought. The latter says expressly that no true knowledge is to be attained through observations of the senses.One leading philosopher who came under Plato's influence was Aristotle (384-322 b.c.) (Fig. 2), the greatest of the early biologists, to
PRINCIPLES OF ANIMAL BIOLOGYGalen.-Rome, though succeeding to a dominant position in world affairs, did not foster learning in scientific fields. Instead of an intellectual revival during her period of prosperity, there was a notable decline.Pliny lived in the midst of this decline. The last great biologist of antiquity was Galen (131-210?), a physician living in Rome but of Greek parentage. References Shari', L.^^^An introduction to Cytology. 3d Ed. McGraw-Hill Book C*onipany, Inc. (Chap. II; details of parts of cells, Chaps. III-VII.) Wilson, E. B. The Cell in Development and Heredity. 3d Ed. The Macmillan Company. (Chap. I.) CHAPTER 3
SOME FUNDAMENTAL PHYSICS AND CHEMISTRYIn the activities of cells, great importance is to be attached to that very fine, mostly invisible, structure which inheres in the chemical composition and minute physical constitution of the protoplasm itself. These features of protoplasm are appropriately discussed along with the physiological processes which depend on them. Such processes should next engage our attention. Since, however, an understanding of this minute structure presupposes a knowledge of elementary chemistry and physics, it is advisable to pause a moment to acquire some of the more important ideas in that field.Composition of Matter.-The physical substance of which objects are composed is called matter. Matter exists in a number of different forms called elements. An element is a svibstance possessing a characteristic structure which is different from that of every other element and which cannot be broken down into substances different from itself (that is, into other elements) by ordinary chemical means. The stipulation "ordinary chemical means" is intended to exclude radioactivity and powerful electronic machines. Among the more common elements entering into the composition of living things are carbon, nitrogen, oxygen, and hydrogen. PRINCIPLES OF ANIMAL BIOLOGY Mitchell, P. H. Textbook of General Physiology. McGraw-Hill Book Company, Inc.3d Ed.(Chap. VII, the chemistry and physiology of proteins, lipids, and carbohydrates; Chap. VIII, the salts; Chap. IX, water and electrolytes.) Rogers, C. G. Textbook of Comparative Physiology. McGraw-Hill Book Company, Inc. 2d Ed. (Chap. Ill, diffusion and osmosis; Chaps. IV and V, structure and properties of protoplasm.) Verworn, M. General Physiology. The Macmillan Company. (Part II of Chap. II, contrast of living and lifeless.)
CHAPTERS CELL DIVISIONWhen cells .were first discovered, and even after it became fairly certain that all organisms were composed of...