4 Journal of Comparative Neurology. 



and after penetrating the layers of the granular zone their fibres con- 

 tinue toward the crus. It has not proven possible to determine 

 whether the fibres anastamose and form a reticulum or whether there 

 is one main branch and lateral nutrient roots as claimed in other 

 cases. Our own impression is that there is considerable lateral anas- 

 tamosis in the neuroglia layers and that fibres after passing into the 

 granular layer soon again acquire medullary sheaths. If, as we be- 

 lieve, the ganglion cells are to be compared with the cells of the spinal 

 ganglia, it would appear that this locus is a point where nourishment 

 is received and hence the myelin sheaths must be interrupted. This 

 space devoid of medullary sheaths is richly supplied with the Deiter's 

 cells which convey the nourishment and also affords the opportunity 

 for intercommunication. The ganglion cells are comparatively large 

 and bear a close resemblance to those of fishes, for example. The 

 nuclei seem to be normally ovoid ; but the cells frequently shrink dur- 

 ing preparation and this shrinkage especially affects the nucleus. 



4. The granular layer is well developed and laminated, each 

 lamina being separated by tracts accumulated from the entad processes 

 of the ganglionic cells. The fibres near the tip seem to pass almost 

 directly through this layer to accumulate at the ventricular surface 

 where they have been considered as forming a part of the pes though 

 actually belonging to the pero. P'arther caudad the course of the 

 fibres is oblique. Two different types of corpuscles may be distin- 

 guished in these granular laminae, one being globular and rather larger 

 than the ovoid and darker bodies which we have supposed might be 

 those connected with the function of formation of sheaths for these 

 fibres, while the former would retain the more purely nutritive func- 

 tion. 



The pes. Cephalad the ventricular epithelium alone represents the 

 core of the lobus olfactorius. The epithelium resembles that of other 

 parts of the ventricular system. A few connective fibres extend into 

 the granular layer and bear the usual dark inoblastic nuclei. Near 

 the point where the lobe joints its crus the pes develops a different 

 ental structure. Here there is an invasion of cortex from the cere- 

 brum. These cells exhibit no orderly arrangement cephalad, but are 

 irregularly disposed and are pyramidal and deeply staining. The area 

 is triangular, being bounded caudad by the peculiar structure of the 

 post-rhinal lobe, from which it is separated by a distinct fibre tract. 



