Biological Chemistry.—Still another experimental field which has developed into one of the most important of the biological sciences relates to the fundamental chemical and physical changes which underlie all organic phenomena. A knowledge of both physiological and physical chemistry is to-day essential for all advanced biological work. The peculiar nature of life itself, of growth, disease, old-age, degeneration, death and dissolution are presumably only manifestations of chemical and physical laws. The ultimate goal of all experimental biology, therefore, will be reached only when the basic physico-chemical properties of life are understood. At that time only will the perennial controversy between vitalism and mechanism be ended.
Economic Zoology.
A moment’s reflection will show that economic biology is the most essential of all sciences to the human welfare and progress. For man’s relation to his environment is such that the penalty for ignorance or neglect of the biological principles involved in the struggle for existence quickly overwhelms him with a horde of parasites or other enemies.
It is only by the intelligent application of biological knowledge that our food supplies, our forests, our domesticated animals and our bodies can be protected from the ever ravenous organisms which surround us.
The losses to food supplies and other products by insects alone amounts to 100 millions of dollars a month in the United States. And the parasites cause losses in sickness and premature deaths each year of many millions more. Then there are the destructive rodents and other animals which add largely to our burdens of support. These enemies next to wars and fungi are the most destructive agencies on earth. Could they but be eliminated man’s struggle against opposing forces would be in large measure overcome. The results of recent work in economic zoology, both in regard to the destruction of enemies and protection of useful mammals, birds and fishes, furnish a bright outlook for the future.
Protozoology.—Partly as an experimental field for the solution of general biological problems and partly because of its practical applications the study of protozoa has now developed into a special science.
The results of the investigations of Calkins, Woodruff, Jennings and others have greatly supplemented our understanding of the signification of such important biological phenomena as reproduction, sexual differentiation, conjugation, tropisms, and metabolism.
From an economic standpoint the protozoa have recently been shown to be of the greatest importance because of the human and animal diseases for which they are responsible.
Parasitology.—The animal parasites of man, domesticated animals and plants include numerous species of protozoa, worms, and insects. Together with the bacteria and a few higher fungi they cause all communicable diseases. When we consider that not only our health but also our entire food supply is dependent upon the elimination of these organisms we must admit that parasitology is the most important economically of all the sciences.
The reports of the investigations of Stiles and his associates in the Hygienic Laboratory and of Ransom and his staff in the Bureau of Animal Industry are widely distributed by the federal government. The systematic studies so ably begun by Joseph Leidy in the middle of the last century have been continued by Ward, Linton, Pratt, Curtis and others on the parasites of many groups of animals.