As long as the nature of eugenic affinities is not established by biogenetic research, we shall assume two practical rules: that psychological nearness or distance is indicative of eugenic nearness or distance and that clinical studies of crossings lead to a preliminary classification of eugenic affinity. We may have to consider not only changes in the genes but changes between the genes whatever mutation may have taken place in a gene and for whatever reason, mechanical and chemical. If this mutation should be favorable the genes must be attractive to one another, that is, must correspond to changes in some other genes. In other words, the genes must be able to produce a functional relation; morphological affinities and disaffinities between them may exist. A definite relation may exist between gene effect, the reflection of one gene upon another and upon the individual characters, and tele effect.