CXLIV. Structure of the cerebral mass. What we know of the brain, 

 serves only to show us that we are ignorant of much more. All that we 

 know of it consists of notions tolerably exact of its external conformation, 

 its colour, its density, and of the different substances that enter into its 

 composition; but the knowledge of its intimate structure is yet a rays-- 

 tery, which will not be so soon unveiled to us. The brain, properly so call- 

 ed, is divided by a longitudinal furrow, into two lobes of equal bulk 

 Gunzius, however, imagined that he found the right lobe, or hemisphere, 

 a little larger than the left; but even were this fact as certain as it is 

 doubtful, we could not thereby explain the predominant force of the right 

 side of the body, since the nerves which are distributed to this side, rise 

 from the left lobe of the brain, in the substance of which all the roots of 

 these cords cross. This fact of the crossing of the nerves, at their origin, 

 is proved by a number of pathalogical observations, in which the injury 

 of a lobe is always found to bring on paralysis, convulsion, or any other 

 symptomatic affection, on the opposite side of the body. Unless you 

 choose to explain this phenomena by admitting a necessary equilibrium 

 in the action of the two lobes; an equilibrium, the disturbance of which 

 is the the occasion that the sound lobe, acting with more force, com- 

 presses the origin of the nerves on its side, and determines paralysis. 

 Might the % want of judgment, the unevenness of humour and character, 

 depend on the want of harmony between the two corresponding halves of 

 the cerebral mass ? 



In order to disclose, better than had been before done, the structure of 

 the brain, M. Gall begins his dissection at the lower part, examining, in 

 the first place, the anterior part of the prolongation, known under the 

 name of the cauda of the medulla oblongata, he finds the two pyramidical 

 eminences. If you part the two edges of the median line, below the fur- 

 row which separates the two pyramids, you see distinctly the crossing of 

 three or four cords or fasciculi of nerves, which, consisting of many fila- 

 ments, tend obliquely from right to left, and vice versa*'. This crossing 

 of nervous fibres, which is not found in any other part of the brain, had 

 been observed by several anatomists. It is not known how it came to be 

 forgotten, so that the mobt exact and latest among them, Boyer, for in- 

 stance, says that the crossing of the nerves cannot lie proved by anatomy. 

 These nervous cords, traced upward, enlarge, strengthen, and forming 

 pyramidical eminences, ascend towards the tuber annulare. Having 

 reached the ganglion, the fibres strike into it, and are lost in a mass of 

 pulpy or greyish substance, of the same nature as that, which, under the 

 the name of cortical substance, covers the two lobes of the brain. This 

 greyish pulp, distributed in various parts, may be considered, agreeably 

 to the views of M. Gall, who calls it the matrix of the nerves, as the 

 source from which the medullary fibres take their origin. These ascend- 

 ing fibres cross other transverse fibres, which, on either side, proceed 

 from the crura of the cerebellum ; enlarged and multiplied by means of 

 their passage through the grey substance which is found in the tuber an- 

 nulare; they rise from it, at its upper part, in two fasciculi which cdfib 



* While dissecting the brain, in 1823, after the manner described by J)r. Gall, lob- 

 served a beautiful and well marked semicircle of fibres, descending 1 from the upper part 

 of the corpora olivaria, on their outside, and after nearly reaching- their inferior points, 

 rising and being continued over the surface of the corpora pyramidalia, until it reached 

 the edge of the tuber annulare. Godman, 



