xiv PROOFS OF ORGANISING MIND 295 



For no two feathers of the twenty or more which form each 

 wing, or those of the tail, or even of the thousands on the 

 whole body, are exactly alike (except as regards the pairs 

 on opposite sides of the body), and many of these are modified 

 in the strangest way for special purposes. Again, what 

 directive agency determines the distribution of the colouring 

 matter (also conveyed by the blood) so that each feather 

 shall take its exact share in the production of the whole 

 pattern and colouring of the bird, which is immensely varied, 

 yet always symmetrical as a whole, and has always a 

 purpose, either of concealment, or recognition, or sexual 

 attraction in its proper time and place ? 



Now, in none of the volumes on the physiology of 

 animals that I have consulted can I find any attempt what- 

 ever to grapple with this fundamental question of the 

 directive power that, in every case, first secretes, or as it 

 were creates, out of the protoplasm of the blood, special 

 molecules adapted for the production of each material 

 bone, muscle, nerve, skin, hair, feather, etc. etc., carries 

 these molecules to the exact part of the body where and 

 when they are required, and brings into play the complex 

 forces that alone can build up with great rapidity so strangely 

 complex a structure as a feather adapted for flight. Of 

 course the difficulties of conceiving how this has been and is 

 being done before our eyes is nearly as great in the case of any 

 other specialised part of the animal body ; but the case of the 

 feathers of the bird is unique in many ways, and has the 

 advantage of being wholly external, and of being familiar to 

 every one. It is also easily accessible for examination either 

 in the living bird or in the detached feather, which latter 

 offers wonderful material for microscopic examination and 

 study. To myself, not all that has been written about the 

 properties of protoplasm or the innate forces of the cell, 

 neither the physiological units of Herbert Spencer, the pan- 

 genesis hypothesis of Darwin, nor the continuity of the 

 germ-plasm of Weismann, throw the least glimmer of light 

 on this great problem. Each of them, especially the last, 

 helps us to realise to a slight extent the nature and laws of 

 heredity, but leaves the great problem of the nature of the 

 forces at work in growth and reproduction as mysterious as 



