562 



THE CEREBRUM. 



campi. There the large pyramidal cells are few in number, and the 

 broad layer in which they occur consequently changes its characters, 

 being split up by layers containing few corpuscles. 



In the Sylvian fissure the fusiform cells are more abundant than 

 elsewhere, and from their number in the claustrum (p. 564) this layer 

 has been termed by Mcynert the " claustral formation." The cornu 

 ammonis is formed almost exclusively of the large pyramidal corpuscles, 

 and the layer in which these corpuscles occur has, in like manner, 

 been termed the " formation of the cornu ammonis." 



Fig. 392. 



Fig. 392. — Minute Strccture of the Cerebral Substance (from Kollilcer), magnified 



220 Diameters. 



A, cells and structui'al elements from the inner part of tlie cortical substance of the 

 cerebral convolutions ; a, larger cells, chietly from the middle grey layer, showing a 

 variable number of radiating processes ; b, smaller cells from the more sui^erficial grey 

 layer, in j)art belonging to connective tissue ; c, a nerve-fibre with its axis-filament 

 partly exposed. 



B, finest nerve-fibres from the superficial white layer of the cortical substance of a 

 convolution, some showing the varicose condition. 



(B.) GREY MATTER AT THE EASES. — The grey matter of the lamina 

 ciiierea, tuber cinereum, and posterior perforated sjiot, appears 

 both in the base of the brain and in the floor of the third ventricle. 

 These collections present many large stellate nerve-cells containing 

 yellowish pigment. From the tuber cinereum a few fibres pass to the 

 optic nerves. The lamina ciuerea is connected externally with the grey 

 matter of the anterior perforated spot, and from that point a continuity 

 of grey matter can be traced to the swelling of the olfactory bulb. 



Olfactory tract and bulb. — The tuher olfadoriwn (or grey root) 

 contains pyramidal nerve-cells, similar to those of the convolutions, 

 but more densely arranged. The oJfadorti irad, or " nerve," consists, 

 in its upper half, of grey matter, containing large granules, nuclei, 

 and small cells, and traversed by a few fibres, continuous with those of 

 the middle root. The other fibres occupy the lower half of the nerve. 

 Olfactory hiilh. — The upper portion is occupied by meduUated fibres, 

 prolonged from the nerve and separated into superficial and deep 

 lamime, by granular substance, the granules being large and arranged 

 in several layers. On the under surface of the bulb is a layer of non- 



