30 Yo^TY.V., Physical Basis of Psychical Events. 



siderable length. The most common cell on the other 

 hand in the occipital cortex, the one which we may 

 assume is concerned in the development of visual sensations, 

 is a small or moderate sized pyramidal cell. 



Let me not be misunderstood here. I am not arguing 

 against the absolute specific character of the cortical cell. 

 On the contrary, as I 'insisted a little while back, the 

 essential note of the whole nervous system is that in the 

 chain of linked units, each unit is marked by specific 

 features, by features unlike those of its predecessor or of its 

 successor. What I am arguing against is the view that in the 

 visual chain such specific characters are to be found alone 

 in the cortical link, or are alone conspicuous in this. And 

 I am perhaps arguing still more against the view that the 

 cortical cell is, as it were, in any sense a terminal, even a 

 temporary terminal link, where alone important psychical 

 labours are commenced, all the preceding links being 

 engaged in nothing more than obscure neural work. 



Indeed, this cortical cell is but one link in a chain, 

 with other links to follow. As I was saying, the axons, 

 the essential part of all these occipital pyramidal cells 

 (and of others not pyramidal), lead away from the occipital 

 cortex to elsewhere. Their goal is threefold. 



In the first place, some lead to cerebral structures 

 lying below the cerebral hemispheres, to the corpus quadri- 

 geminum and other bodies. Among these are the axons 

 of the large motor cells of which I have just spoken ; and, 

 indeed, all the axons taking this course are probably linked, 

 by a course more or less short, with motor mechanisms, 

 notably with the mechanisms for movements of the eyes, 

 but probably also with others. Some few, we have reason 

 to think, are the instruments for carrying out, through 

 efferent action, changes in the retina, by which the receptive 

 cones, and possibly other structures, are tuned to their 

 work, but concerning this our knowledge is imperfect. 



