main line of defence, or more correctly what Hindenburg would call “offensive-defence,” is therefore made to rest on the phenomena of hair-direction, which, I submit, are impregnable to the forces of selection, probably in all the hairy mammals, but certainly in that hairy animal called Man. [40] Jevons. [41] British Association of Science 1902. Zoological Section. 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. Procedure. The order of proceedings may be tabulated thus:-- (1) Observation of selected facts. (2) Evidence that certain of these are produced in the lifetime of the individual. (3) Evidence that among the facts of direction of hair and others there is to be seen an orderly evolution rather than a casual appearance of the changes noted. (4) An hypothesis as to their production. (5) Exclusion of selection as a possible cause of these, and of correlation as properly understood. (6) Experiment in verification of the Lamarckian interpretation of the phenomena. And here, before I hear some Prince Henry of the genus Weismann, Mendel or Gallio groan aloud: “This intolerable amount of sack,” I proceed to offer him a few loaves of home-made bread. CHAPTER VI. EVIDENCE FROM ARRANGEMENT OF HAIR. _Ex Uno Disce Omnes._ The singular arrangement of hair on the forearm of man is the subject of some curious statements by Darwin, Wallace and Romanes, and these suggested to me twenty years ago the following line of thought. To many minds the text will appear a humble one, but it opens many avenues of inquiry.