Dr. Foville's Besearches on the Anatomy of the Brain. 335 



If when we have separated all the planes, so as to see their 

 reciprocal relations, we make a transverse vertical section of 

 the brain at that part which corresponds to the coronal suture, 

 we may observe at the centre of this section a surface of two 

 inches'in diameter, which nearly resembles the section of a 

 cylinder. The circumference of this cylinder, which is slightly 

 hollowed both above and below, is entirely composed of me- 

 dullary matter. About the middle of its thickness we see on 

 each side a large white surface, above and below which are 

 two gray surfaces. The planes of the hemispheres extend to 

 the right and left from the sides of this cylinder, and do not 

 exceed two lines in thickness. 



If we compare this section with a transverse section of the 

 spinal marrow, we cannot help being struck with the remark- 

 able analogy which exists between the spinal marrow and the 

 central part of the brain. 



In both, the external part is extremely white ; in both there 

 are four gray surfaces separated by medullary matter, the pro- 

 portion of which it is true, differs, in the two cases, but the 

 analogy is preserved in the arrangement. Lastly, the nerves 

 which rise from each side of the spinal cord are represented 

 by the plane of the hemispheres, which we may consider as a 

 series of nerves in close apposition. 



This analogy is by far the most striking when the compari- 

 son is made wTth a section of quite the upper part of the spinal 



cord of an infant. • i i u • 



An important observation may be made with the brain ot 

 a child of two or three years of age. A transverse vertical 

 section at the part opposite to the coronal suture displays the 

 arrangement above described. Simple but well-defined white 

 lines mark the central cylinder, analogous to the spinal mar- 

 row, and indicate the course of each of the three planes, which 

 are not to be distinguished in the adult brain until they have 

 been artificially separated. 



Physiological Section. 



It follows as a consequence of the single analogy which 

 I have pointed out, that to the central part of the brain must be 

 attributed functions analogous to those of the spinal cord, and 

 tiiat the outer parts of the brain must be regarded as devoted 

 to the special functions of the brain itself. 



The plane of the hemispheres being analogous to the spinal 

 nerves, will in this view be regarded as the medium of reci- 

 procal communication between the central and the circum- 

 ferent parts of the brain. 



These physiological conjectures, which wc have noticed as 



jiimply 



