Thesis.

If these groups of phenomena were being studied apart from the hypothesis they support, a much more full treatment of all of them would be required, such as I have given to those of hair-direction in a book published in 1903 on Direction of Hair in Animals and Man. The limited thesis, however, here upheld is that the phenomena are produced by the factors of stimuli and response in the course of the total experience of the organism, that the essence of the matter is the produc­tion of initial modifications, that instances of these in well-known animals are produced before our eyes by ascertainable mechanical stimuli, and that, especially in those of hair-direction, experiment is adduced in proof of the thesis that some modifications are transmitted.