42 Precentral or Motor Area [CHAP. 



In this manner serial sections of specimens were obtained, illustrating the condition of 

 the cortical nerve cells of the central convolutions from top to bottom, at intervals of three 

 millimetres. 



As to the postcentral gyrus, this is soon dismissed, as nothing marked in the shape of 

 abnormality or disease was detected in its contained cells. 



With the precentral gyrus. however, it was otherwise, and the alteration which at once 

 caught the eye was the scarcity of giant cells. Deferring, for the moment, the topographical 

 distribution of the giant cell affection, I shall begin by giving a general description of the 

 appearances. (Plate IV., Figs. 1 and 2.) 



In the first place, a shallowness of the cortex was obvious, and, secondly, there was such 

 a disturbance of the general columnar formation, and such a distorted arrangement of the 

 individual cell elements, that it was almost impossible to identify or differentiate the various 

 laminae which normally exist. Indeed, the only laminae which preserved an approximately 

 normal appearance were the relatively unimportant plexiform layer and the layer of small 

 pyramidal cells ; and even in the former there was a reduction in depth, probably due to 

 the disappearance of apical dendritic terminations of the giant and other pyramidal cells. A 

 differentiation into layers of the middle-sized and external large pyramidal cells was almost 

 impossible, and the impression was given that most of the latter cells had disappeared, or 

 at any rate been reduced to shapeless, processless masses, no larger than the ordinary middle- 

 sized pyramidal cell. It was also observed that the elements remaining had dropped out of their 

 normal position and lying at all angles to the surface created great confusion of arrangement. 

 Not only was the appearance of a stellate layer wanting, but the position which it should have 

 occupied defied orientation. The large pyramidal cells in the depth of the cortex showed atrophj' 

 and distortion similar to that noticed in the external layer. 



Coming now to the giant cells of Betz, I have already mentioned that these elements were 

 scarce, but I can illustrate my point better by mentioning the results of a comparison between 

 sections taken from the top of the precentral gyrus in this brain, and ones of the same 

 size taken from a corresponding position in a normal brain. Now for this comparison I 

 purposely chose this part, because it is one in which one invariably finds giant cells in greatest 

 abundance ; and whereas an enumeration of the cells in the series of normal sections gave an 

 average of 40 per section, those from the diseased brain yielded a bare average of 5, that is to 

 say, there was a deficiency of 87'5 p.c. Although, as I shall presently point out, there were 

 areas from which the giant cells had entirely vanished, these figures may be accepted as indicating 

 the general average shortage, and, if they err at all, it is on the side of under-representation 

 of the deficiency. In the next place, when we examined the few remaining Betz cells, we 

 found that hardly any would pass the normal standard, and as indications of degeneration or 

 atrophy we noticed a distinct degree of chromatolysis, a dislocation of the nucleus, a swelling 

 of the cell body, and malrepresentation of the dendrites. Further, when search was made for 

 the remains of degenerated cells, nothing could be found excepting some insignificant-looking 

 collections of small round cells, and that these marked the position of pre-existent cells was 

 uncertain. 



In addition to these profound changes affecting cell-lamination, coexistent vascular affection 

 is to be mentioned. All over the diseased field the blood vessels were extremely dilated and 

 congested, and hence stood out very prominently, but, in association with this, a slight thickening 

 of the wall was the only condition which could be called pathological. 



