Nuclei Tuheris Laterales and the Ganglion Opticuin Basale. 19 



tuberis, except in one case, there is absolutely no reason to believe that 

 any of them have had in mind the characteristic nests of cells which 

 will now be described. Kolliker undoubtedly saw these nuclei, 

 although, as will appear later, his description is faulty and his figures 

 incorrectly labeled ; the result is so confusing that a careful study of 

 this region is necessaiy to appreciate the value of Kolliker's observa- 

 tions. In the previous brief description I employed the name nuclei 

 tuberis, but in the present article adopt the name nuclei tuberis later- 

 ales. The name nuclei tuberis is nor distinctive and might be used to 

 indicate any cell group whatsoever located in the tuber cinereum; as 

 a matter of fact it has been so used, and the resulting confusion may be 

 imagined when one considers how many different cell groups lie in the 

 tuber cinereum. This confusion is not one merely of names, but 

 involves the failure to distinguish (regardless of names) various cell 

 groups of the tuber cinereum which in properly prepared material may 

 be readily distinguished not only through differences in location but 

 also through striking differences in cell type. 



Location and extent of the nuclei tuberis laierales. 



The nuclei tuberis laterales consist in man and macacus of several 

 nests of cells located on the periphery of the tuber cinereum. In the 

 lemur in this location one sees the beginning differentiation of these 

 cell groups from the cells which surround them, although these differ- 

 ences are so slight that I have not attempted to show them in the illus- 

 trations. In the cat these cell groups are absent. 



MAN. 



In Series AC of man the nuclei tuberis laterales are shown in Figs. 

 1 to 8; the size of the cells, however, has been so much reduced that 

 they should be examined with the aid of a hand lens. In Pig. 1 two 

 indentations are shown on the base of the brain which should be 

 noted. One indentation marks off on the base of the brain the medial 

 boundary of the pes pedunculi, while the more medial indentation 

 forms the superficial boundary between the tuber cinereum and the 

 nucleus tubero-mammillaris (nucleus mammillo-infundibularis), this 

 nucleus lying between these two fissures. The area bounded by these 

 two fissures ventrally, and by the columna fornicis dorsally, is of 

 especial importance in describing the location of the nuclei tuberis. 



