L. V. Krushinsky (1911–1984) was the professor of Moscow University, member by correspondence of USSR Academy of Sciences, Lenin prize winner, the prominent soviet biologist. Two volumes of L. V. Krushinsky selected papers include works which are most important and most interesting for modern reader.

The first volume include his earlier investigations which are still important now. The book includes theoretical and experimental works on genetics and evolution of behavior, on phylo- and ontogenetics rules of behavioral development. The importance of nervous system excitability as the factor influencing the penetrance and expressivity of normal as well as pathological behavioral and physiological reactions was demonstrated. The origin of instincts is discussed, as well as the hereditary and environmental factors influencing the development of behavioral reactions. The concept of unitary reactions was introduced, these reactions being the result of inborn and acquired elements integration. The problems of individual development and evolutionary aspects of unitary reactions are presented.