Herrick, Morfhology of Nervous System. 19 



The intra -ventricular lobe, or that portion mesad of the 

 lateral ventricle, becomes quite distinct dorsad by the sepa- 

 ration from the thalamus and backward extension of the 

 ventricle. It is filled with irregularly dispersed flask cells, 

 and also contains the cephalo-dorsad prolongations of the 

 callosal tracts. The finer structure of the intraventricular 

 lobes may be gathered from the figures (Plate II, Fig. t6, 

 and Plate IV, Fig. 8). The portion drawn in Fig. 8 is from 

 that part of the lobe near the ventricle of the right hemi- 

 sphere. The epithelium of the ventricle is produced, as 

 usual, into long connective fibres, which do not appear in 

 the figure because the section is oblique to their axes. The 

 entire lobe is filled with bipolar 01 multipolar cells, with 

 the large reticular nuclei and generally fusiform contours of 

 aesthesodic cells. The fibres do not preserve any definite 

 direction, but the long axis of most of the cells lies in the 

 horizontal plane and prevailingly in the cephalo-caudad di- 

 rection, while a smaller number extend perpendicularly or 

 obliquely. The drawing was made under a one-fifteenth 

 inch objective, with the aid of approximate micrometer 

 measurements. 



The course of the fibres of the callosum may be traced in 

 transverse sections. At the point of crossing, the intra-ven- 

 tricular lobe fuses with the thalamus, but cephalad the 

 callosal fibres pass through that lobe dorso-cephalad until 

 part of them pass dorsally to the ental aspect of the fronto- 

 median lobe {i.e., to the ventricular side) and thence to the 

 dorsal cortex. 



Medianly and ventrally the intra-ventricular lobe passes 

 into that part of the axial lobe cephalad to the chiasm. 



In higher sections the fronto-median lobe extends caudad 

 and overlaps the intra-ventricular lobe on the median as- 

 pect. In the meantime the free caiidad margin of the 

 cortex has extended medianly, receiving the taenia from 

 the habena and then fusing with the intra-ventricular lobe, 

 and ultimately uniting with the fronto-median. completing 



