SEC. 3. THE DISPOSITION AND CONNECTIONS OF 

 THE GREY AND WHITE MATTER OF THE BRAIN. 



The Grey Matter. 



613. As we pass up from the bulb to the higher parts of the 

 brain, the differentiation of the grey matter into more or less 

 separate masses, which we have seen begin in the bulb, becomes 

 still more striking. We have to distinguish a large number of 

 areas or collections of grey matter more or less regular in form and 

 more or less sharply defined from the surrounding white matter ; 

 to such collections the several terms corpus, locus, nucleus and 

 the like have from time to time been given. These areas or col- 

 lections vary greatly in size, in form and in histological characters ; 

 they differ from each other in the form, size, features and arrange- 

 ment of the nerve cells, in the characters of the nervous network 

 of which the nerve cells form a part, and especially perhaps in the 

 extent to which the more distinctly grey matter is traversed and 

 broken up by bundles of white fibres. Guided by the analogy of the 

 spinal cord, as well as by the results of experiments and observa- 

 tions directed to the brain itself, we are led to believe that the 

 complex functions of the brain are intimately associated with this 

 grey matter ; and a full knowledge of the working of the brain will 

 carry with it a knowledge of the nature and meaning of the 

 intricate arrangement of the cerebral grey matter. At present, 

 however, our ignorance as to these things is great ; and, though 

 various theoretical classifications of the several collections of grey 

 matter have been proposed, it will perhaps be wisest to con- 

 tent ourselves here with a very broad and simple arrangement. 

 We will divide the whole grey matter of the brain into four 

 categories only. 1. The central grey matter lining the neural 

 canal ; and with this we may consider the nuclei of the cranial 

 nerves some of which are closely associated with it. 2. The 

 superficial grey matter of the roof of some of the main divisions 

 of the brain, such as that of the cerebral hemispheres, and of the 

 cerebellum. 3. The intermediate grey matter more or less closely 



