"DIRECTIVITY" A WITNESS OF MIND 85 



ground of the difference must be sought for in the cause 

 of the determination of molecular motion. 



" Here in this region the doctrine of Natural Selection 

 and the struggle for existence can afford no more light on 

 the matter than the fortuitous concourse of atoms and the 

 atomical philosophy of the ancients." 



Mr. Croll's imagery of a house recalls that of Darwin's 

 to which I shall refer, where I endeavour to show that if 

 naturally made fragments of rocks — supposed to represent 

 casual, favourable variations in organisms — were taken 

 with the purpose of building a "noble and commodious 

 edifice," such was impossible ; for no such house has ever 

 been built nor could be, with undressed stone. 



Mr. Croll introduces another point. Supposing the 

 fragments were suitable, how are they to move from the 

 base of the cliff and find their proper places in the edifice 

 without a "director" who fits them in just where they 

 are to go? If the analogy between Darwin's noble and 

 commodious house and an organism be carried out, then 

 the bricks must be made for walls of the house, just as 

 molecules of cellulose must be made for cell-walls of 

 plants or of bone and enamel for teeth of animals. 



Secondly, being made, the former have to be located 

 on the periphery of the protoplasm, and those required 

 for the teeth to be placed in those organs and nowhere 

 else. 



There is first the preparation of the right chemical 

 molecules out of food to be gone through, and, secondly, 

 Directivity or Determination to locate them in the being. 



A writer of an article on "The Atomic Theory of 

 Lucretius " observes : " It is a principle of mechanics that 

 a force acting at right angles to the direction in which a 

 body is moving does no work, although it may continu- 

 ally and continuously alter the direction in which the 



