272 Journal of Comparative Neurology. 



form is usually pyramidal although it is difficult to always strike 

 the right plane for making sections; a deviation from it pro- 

 duces pictures like the real motor neurones in the ventro-lateral 

 lamina of the neural-tube. To judge from numerous specimens 

 it would, however, be wrong to say with Nissl that they were 

 not pyramidal. 



In structure, they represent the ' motor ' type. The large 

 lumps of stainable substance are regularly arranged, leaving 

 plain paths for the non-stainable substance which contains the 

 fibrils. The apex-process and the lateral processes have a very 

 neat arrangement of longitudinal spindles. The nucleus and 

 nucleolus are very large. A number of drawings which lately 

 appeared in the Journal of Insanity^ give a fair idea of both the 

 normal and certain abnormal conditions of this type of cells, at 

 least figure i, 4, 6 and 7. The writer describes several alter- 

 ations of the cell-body ; for Figs. 3 and 4 he urges the proba- 

 bility of a lesion of the neurite, for Fig. 6 and 7 toxic pro- 

 cesses ; but we necessarily miss statements concerning the fate 

 of the fiber-part of the neurones, since it would be impossible 

 at present to study their fibers thoroughly in their whole extent; 

 the real terminations of the pyramidal fibers especially being 

 only little known, and no methods for their isolated study be- 

 ing available. The efferent cerebral neurones which are not a 

 part of the pyramidal system are comparatively little known. 

 Apart from the studies of v. Monakow and Moeli there are 

 very few data, and even these are hardly sufficient to establish 

 any satisfactory description of these ncmones. There are many 

 well founded suppositions ; but suppositions are not neurones.^ 



There are quite a number of intra- and inter-cortical nerve- 

 elements, cortex-cells of which we might give descriptions here, 



' Demonstration of various types of changes in the giant cells of the para- 

 central lobule, by Adolf Meyer, M.D. American Journal of Insanity, Vol. 

 LIV, No. 2. 



^ Through an oversight the cerebral efferent supply of the third, fourth and 

 sixth nucleus is represented in the 'plan of the brain ' as coming through the 

 pyramids. It is more probable that the origin of these elements lies in the large 

 cells of the visual area and that their course is independent. 



