133 



of slender fibres not really in structural continuity with the 

 fibre from which they seemed to sj^ring. 



Arndt further describes the turning round of the apex 

 fibre, so as to be possibly continuous with vertical fibres 

 comino- up from the white substance ; but of this it would 

 be well to have further evidence before it is received as a 

 fact ; for the apex fibres are liable to be disturbed from their 

 proper position in making the section ; and a good many of 

 the archings figured by Arndt look very much as if they 

 were due to that cause. From the base of each pyramidal 

 corpuscle, especially Avhen it has been isolated, may be seen 

 to come off several extremely delicate processes, which take 

 diflferent directions and are often branched. 



Arndt believes that these basal processes are never con- 

 tinued into any nerve fibres, while Lockhart Clarke describes 

 them as running " partly toward the centre to be continuous 

 with fibres radiating from the central stem, and partly 

 parallel Avith the surface of the convolution to be con- 

 tinuous with arciform fibres." 



This is a very difficult point to make certain with regard 

 to the typically pyramidal corpuscles ; but my own observa- 

 tions entirely favour Lockhart Clarke's view. If Arndt had 

 studied the position of these basal processes when undis- 

 turbed and embedded in the surrounding textures, he would 

 have seen that they have not the rounded curves which he 

 represents in his scheme, but are stretched, for the most part 

 horizontally, and sometimes also vertically, so that it seems 

 extremely probable that they are continued into fibres 

 running in these difierent directions. 



Even Arndt, who strains to represent all the nerve cor- 

 puscles of the convolutions as founded on the pyramidal 

 form, has to own that this shape is altered, as if by distortion, 

 in many instances, and, in point of fact, represents fusiform 

 and otherwise shaped corpuscles which have come under his 

 own observation. These various shaped corpuscles are most 

 numerous in the parts subjacent to the primary pale band ; 

 and indeed Lockhart Clarke, in describing those medullated 

 horizontal fibres which I have pointed out to be the inner 

 limit of that band, states that " they are thickly interspersed 

 with large and small cells of different shapes.^' Apparently 

 fusiform corpuscles are not infrequent at this level, for the 

 most part placed vertically, but sometimes also horizontally. 

 It is more questionable, however, that these fusiform cor- 

 puscles are really only bipolar, as it must be admitted that 

 when they are imbedded in texture, small processes given 

 off from the sides are liable to escape detection. In one instance, 



VOL. X. NEW SEK. K 



