Nuclei Tuheris Laterales and the Ganglion Opticum Basale. 1 



appear to be components of one large cell complex, and while differing 

 from one another, differ much more from the surrounding cells. These 

 relations will be discussed later in detail. 



5. Corpus hypothulamicum (Luysii) 



This is such a compact, isolated cell mass, and is situated at such a 

 distance from the basal optic ganglion and the nuclei tuberis that no 

 description is necessary ; it has been included in the illustrations, how- 

 ever, for the purpose of orientation. 



6. Substantia reticularis hypothalami. 



This group of cells on account of its position need not be considered 

 in this article. A description will be found in my monograph on the 

 diencephalon. Many of its cells are of a motor type of structure, and 

 these together with the cells of the nucleus intercalatus of the corpus 

 mammillare are the only cells of the entire diencephalon which show 

 the histological character peculiar to motor cells. 



7. Substantia grisea ventricuK tertii. 



This cell mass is shown in all series and the cell type in Figs. 40, 46, 

 51 and 56. The greater portion lies in the pars optica, and it should 

 be noted that dorsally and laterally the cells are less densely packed 

 than ventrally and medially. The substantia grisea is closely related 

 to the nuclei tuberis, and this relation will be fully discussed in connec- 

 tion with the description of the nuclei tuberis. 



If we now observe in the illustrations the location and extent of the 

 different cell groups previously described and note also the character of 

 their cells in the different mammals, we shall be prepared to understand 

 the following description of the basal optic ganglion and the nuclei 

 tuberis and the consideration of the relations of the latter two nuclei to 

 the fonner. 



Ganglion Opticdm Basale. 



The name ganglion opticum basale was given with the intention of 

 implying a function which this cell group almost certainly does not 

 possess ; on the other hand this name effectively distinguishes this cell 

 group from the nuclei tuberis with which it has been confused. Since 

 the so-called basal optic ganglion is such a characteristic cell group, and 



