CONSCIOUSNESS AND SENSATION. i O I 



structure may reasonably be supposed to arise 

 from the different relations in which the different 

 parts of the hemisphere lie to the corpora striata 

 and from unequal development of the nerve-cor- 

 puscles ; a supposition in favour of which is the 

 circumstance that in the posterior lobes, the parts 

 furthest from the corpora striata, the nerve-cor- 

 puscles are least developed, and the horizontal 

 fibres are most abundant. 



But not only does the study of structure thus 

 point to the probability of the whole hemispheres 

 having one combined function, but development, 

 comparative anatomy, and experiment point to the 

 propriety of considering the corpora striata as 

 forming with the hemispheres one organ. The 

 corpora striata are enlargements of the basal por- 

 tions of the hemisphere-vesicles ; so says develop- 

 ment : they are inseparable from the islands of 

 Reil ; so says adult structure. They may be 

 irritated or damaged by vivisection in mammals, 

 without damage to sensation or motion, and slic- 

 ing them away in birds produces effects corres- 

 ponding with those produced by slicing away the 

 hemispheres in mammals ; that is the evidence 

 of experiment : while comparative anatomy shows 

 the hemisphere-vesicles forming each a unity in 

 fishes, a small distinct corpus striatum within 



