CHAP. XI.] UNCONSCIOUS COGNITION. 157 



' learns ' to discriminate one impression from another, 

 either unconsciously or consciously as we are compelled 

 to infer, from the different nature of its motor responses 

 and the suitability of each as an answer to the impression 

 which it follows. Thus ' discrimination ' comes to be an 

 essential result or concomitant of the action of even the 

 simplest nerve tissues.* 



And as ' discrimination ' is generally recognized by 

 philosophers to be the root faculty or most fundamental 

 manifestation of Intelligence, we shall find in the 

 phenomena of Eeflex Action, now about to be illustrated, a 

 further strong support for the view that the nervous 

 system generally is to be regarded as the Organ of 

 Mind. 



In most lower animals, as we have seen, several separate 

 Nerve Centres, or Ganglia, constitute the main subdivisions 

 of the nervous system. In animals like the Centipede, 

 these ganglia are very numerous, and distinct from one 

 another ; in others, such as the Grasshopper, several 

 become fused at intervals, so that separate ganglia are 

 less numerous ; while in Vertebrate animals, as we have 

 seen, the fusion is carried still further. In the Fish, the 



* Something very like organic discrimination may occur in 

 Plants. A writer in u Nature " (June 26, 1873, p. 164) cites what may 

 be regarded as an instance of this. He says: "The Ivy Linaria 

 grows on an old wall; its flowers and the flower-stalks stand out 

 for the sun and Insects to visit the little ' snap-dragon.' But no 

 sooner does the corolla fall than the peduncle begins to curve in- 

 wards to the wall, and usually contrives to tuck its seed-vessel well 

 into the brickwork again." An action like this may perhaps be 

 the result of an organic impulse or tendency fostered, it not engen- 

 dered, by ' natural selection.' And as the observer intimates, there 

 are certain obvious relations between such a process and some of 

 the instinctive actions of animals in connection with ovi-position. 



