Common observation and reasoning convince us without question that musicality is inherited in some mysterious way and this follows also from general considerations of current theories of biological inheritance. But when it comes to the scientific determination of laws of such inheritance, we face high barriers. Biological laws of inheritance must be established in terms of the genes; a specific biological structure or function must be related to gene organization. Let us call this measurement of the first order. Such measurements are most readily applied to anatomical structure and physiological function in the neuro-muscular organism. This is notably clear in the anatomy and physiology of the ear and its connections. It is equally applicable to the anatomy and physiology of the vocal organs--the bellows, the vibrators and the resonators for voice. It is conceivable, for example, that the length, the mass, the mode of attachment, and the general position and shape of the vocal cords and the mounting of the voice box are heritable characters traceable to genes and referable to musicality as the physical organs for voice. We can also find relationships to the endocrines, which are in large part the determinants of musical emotionality. Electro-physiology is now giving great promise for the identification of functions in the ear and the brain and its central connections and is establishing interrelationships. Many of the laws of heredity established by measurements of this order probably refer to fundamental biological principles of inheritance in the psychophysical organism as a whole. By a physiological analysis of the sensory, motor, and central factors which operate most significantly in music, the systematist can set up a respectable body of biological facts in regard to musical inheritance which are antecedently probable in terms of the functions of genes and result in the structure and function of the musical organism. Since the medium of music is sound, we shall look first for an exceptionally responsive or unresponsive ear, including not only the physical ear but the central organs in the nervous system through which it functions. This is basic for two reasons: First, because it determines what stimulation from the world of sound shall enter into the experience of the musical individual to a high degree; and second, because the purely physiological receptivity or organic response to sound acts upon and modifies the state of well-being or ill-being according as the auditory impression is beneficent or noxious in so far as its acts upon our circulation, metabolism, temperature and other organic processes. Such well-being or ill-being is, of course, in part the foundation for the feeling of musical pleasures and pains.