Shvarts S.S.
The study of the complex of morpho-physiological peculiarities in animals under natural conditions may be successfully applied to the development of certain ecological and general biological problems. In the works of the Laboratory of Zoology of the Institute of Biology (Acad. Sci. USSR) the size of heart, liver, kidneys, pancreas, intestine and its sections, hypophisis and adrenal gland, the content of erythrocytes and hemoglobine, activity of certain digestive enzymes, vitamin A content in liver and some jther anatomical and physiological characters of animals were used as the principal indices.