62 PRESENT-DAY RATIONALISM 



physico-chemical processes till it became flesh, bone, 

 skin, hair or feathers, etc., what kinds of physical or 

 chemical forces were they which brought about two so 

 diiiferent results as the " form " of a cat and that of a 

 hawk, one having hair and the other feathers, not to add 

 that these animals develop different habits and different 

 methods of propagation ? 



From having been molecules of food such become 

 molecules in the blood, ready to be located in their proper 

 places in the animals' bodies. They then require some 

 directing to put them there ; so that every part, bone, 

 claw, feather, teeth or beak, etc., receives just what it 

 wants and no others ; as on repairing a house, stones, 

 bricks, wood, slates, etc., are placed by the builder wher- 

 ever a house may require any restorations. What purely 

 chemical or purely physical force (such as occurs in the 

 inorganic world) is capable of carrying out this selective 

 process and whence arises the very obvious Directivity ? 



Now all this is greatly extended by Evolution. It is 

 not enough to explain how the same form is reproduced 

 by heredity as kittens or young hawks, but variation 

 occurs when the environment is changed. Adaptive 

 variations appear through the responsiveness of proto- 

 plasm to the direct action of the new conditions of life. 

 Here again Directivity asserts itself The direct action 

 is upon the surface of the organism externally or in- 

 ternally as food ; but the response is deep-seated in the 

 nuclei of the merisinatic cells, which divide and build up 

 tissues in adjustment to new requirements. It is the 

 nuclei which are the ultimate originators of cells ; but, 

 having made them, the cells during growth assume the 

 necessary forms to meet the new requirements. 



Thus, as stated, if strains be put upon stem, petioles, 

 etc., beyond what are normally sustained by a plant. 



