In view of these discoveries, it is evident that there is some material available for technically rigid genetic interpretation in terms of currently recognized principles of inheritance. All the records on the six foremost musical families of America are available in the confidential files of the Carnegie Institution, at Cold Spring Harbor. Highly reliable measurements on all the students in the Eastman School of Music for the last fifteen years are available. Various public schools have vast cumulative data, and elaborate collections are being worked upon in the Winderen Laboratory, at Oslo. But with the exception of the Carnegie Institution and the Oslo collections, adequate measurements of whole families are absent. What is needed now is a thoroughly reliable series of measurements on entire musical families and the interpretation of these by a thoroughly competent geneticist in terms of established biological principles of inheritance. It is especially important that both parties shall be competent to take into account the numerous lessons which we have learned from the extensive efforts that have been made in the attempt to measure the inheritance of any mental trait, such as human intelligence. In the human situation we cannot breed successive generations rapidly, as in flies or mice, for experimental purposes. We must, therefore, economize time and effort by taking the most readily available material. For this purpose I have suggested three possible methods (_Psychology of Music_, McGraw-Hill, 1938). The first is that we start with the highest 10 per cent and the lowest 10 per cent in an adequate sampling of fifth-grade children in a school system and work back by making the same measurements on the available blood relatives of these two groups. In effective organization much time can be saved by making group measurements in a co-operating community, such as a city ward. A second procedure would be to secure an adequate sampling of musicians and measure forward and backward to cover three generations in which the matings of musical and unmusical parents could be traced. A third procedure would be a systematic collection of measurements on school children for a generation or more giving special attention to the showing of blood relatives. We cannot, however, stress too strongly the importance of having these measurements made throughout by an experimenter thoroughly competent in this field and the equally thorough biological treatment of data by scientists thoroughly competent in that specific field. If a biologist wants to start the ball rolling from his point of view, the records in the Eugenics Record office of the Carnegie Institution furnish a fair and reliable sampling.