296 LEISURE-TIME STUDIES. 



the exterior and interior was at last established, and nerve- 

 force flowed in established pathways, which in their turn 

 represented the nerves of the future. Finally, as organisation 

 advanced, and with the necessity for the establishment of a 

 clearer relationship with the world around, the external 

 layer of the body, which 'itself originally received the rude 

 shocks of the outer universe, and which was thus by habit 

 impressed with a facility for such reception, became in- 

 folded, and the nerve-pathways were brought into relation- 

 ship with the nerve-centres thus formed. Then, also, special 

 parts accustomed to receive impressions of peculiar kind 

 participated in the new era of development, and became 

 infolded, as the sense-organs, so as to communicate with the 

 great nerve-centres within. Purpose and design, as regulated 

 by necessity and use, were thus illustrated to the full ; and 

 as the relationship between the living being and the outer 

 world became fully established, we may then conceive of the 

 dawn of intelligence, and of the powers which successively 

 mark the higher animal and the man. 



Thus development teaches us through its marvellous 

 story, first, that the formation of man's nerve-centres is 

 affected through the same stages and by the same means as 

 those of all the members of the great division of the animal 

 world to which he belongs ; and secondly, that the genesis 

 of nerves is due primarily to the contact of the world with 

 sensitive parts of living beings, and to the effects of habit 

 and use in the further development of these parts to form 

 nerves. It is not given to science to trace the exact 

 stages or processes through which the powers of mind have 

 become evolved. But once determining that there is the 

 closest of relationships between the structure and formation 

 of the human nervous system and that of lower forms of 

 life, cells and fibres of the same nature entering universally 

 into the structure of nervous systems, we must logically 

 assume that man's mental powers are as strictly dependent 

 on the physical characters and qualities of his nervous sys- 

 tem as the acts of the medusa are upon the perfection of 



