OH. xiy.] LIFE AND MIND. 91 



grains, may be considered as simply a paitof the surface more 

 irritable by light than the rest. Some idea of the impression 

 it is fitted to receive may be formed by turning our closed 

 eyes towards the light, and passing the hand backwards and 

 forwards before them." But while this localization of sen- 

 sibility enables the creature to adapt itself to the movements 

 of neighbouring opaque bodies, the extension of the corre- 

 spondence is nevertheless very slight. To produce noticeable 

 obscuration the opaque object must approach very near ; and 

 hence " we may infer that nascent vision extends to those 

 objects alone which are just about to touch the organism, 

 .... so that it amounts at first to little more than anti- 

 cipatory touch." ^ As we pass to higher forms, we find the 

 eye gradually increasing in translucence, acquiring convexity 

 of surface, liquefying internally into refracting humours, 

 while the nerve-vesicles within multiply and arrange them- 

 selves as retinal rods ; the result being seen in the gradually 

 increasing power of the organism to adapt its actions to 

 actions occurring at a distance. The process and the result 

 of development are essentially the same in the case of 

 hearing and smell, though there are great differences in the 

 degrees to which these senses are developed in the highest 

 animals. 



Further extension of the correspondence is eff'ected, in 

 the higher vertebrates, by the increase in size and complexity 

 of the cerebrum and cerebellum. These pedunculated groups 

 of ganglia, which issue from the medulla, and whose function 

 it is to compound in higher and higher aggregates the 

 ftlready-compound impressions received by the medulla, are 

 capable of adjusting inner relations to outer relations beyond 

 the reach of the organs of sense. "Chased animals that 

 make their way across the country to places of refuge out of 

 view, are obviously led by combinations of past and present 

 Impressions which enable them to transcend the sphere of the 

 * Speacer, Principles of Psychology, toL L pp. 314, 315. 



