18 Edward F. Malone. 



optic ganglion by tlie large size of its cells. In man, as was pointed 

 out by Kolliker, the cells of the ganglion basale may be readily separated 

 from those of the basal optic ganglion by the fact that they are heavily 

 pigmented (Fig. 42). In a previous article I have discussed the value 

 of pigmentation as a basis of distinguishing different cell types. 

 Yellow pigment occurs in certain nerve cells of the adult human and 

 increases with age, but this occurrence and increase in amount is not 

 errntic, but behaves differently with respect to different types of cells. 

 Some types of cells never contain pigment, others always contain it, 

 while still other types may contain none or under other conditions may 

 contain a small or even a moderate amount. But however the total 

 amount of yellow pigment in the brain of different adults may vary, 

 the amount in each specific type of cell retains the same relation to that 

 of every other type of cell ; in other words, the relative amount of pig- 

 ment in the different types of cells is constant in all individuals. Note 

 that this pigmentation of the cells of the ganglion basale in man is 

 accompanied by an additional characteristic (large size) and that the 

 homologous cells of macacus and the lemur are entirely different from 

 those of other cell groups, although pigmentation is of course lacking. 

 This question of the relative amount of yellow pigment as a character- 

 istic of certain types of cells which differ also in other respects will be 

 noted again in connection with the nuclei tuberis. This yellow pigment 

 should not be confounded with the brown pigment which occurs in the 

 cells of the substantia nigra and elsewhere. 



Now that the differences in cell type between the cells of the basal 

 optic ganglion and those of surrounding groups have been studied it 

 woiild be desirable to consider the relationship of these various cell 

 groups from the standpoint of similarities in cell character. This 

 consideration, as well as that of the literature, must however be post- 

 poned until the nuclei tuberis have been described, since such a com- 

 parison of the various cell groups demands a familiarity with the 

 nuclei tuberis and the substantia grisea of the third ventricle. 



Nuclei Tuberis Later-^les. 



Under the name of nuclei tuberis laterales I shall describe certain 

 cell groups of the pars optica hypothalami (telenceplialon) which I 

 have formerly considered very briefly in my monograph on the human 

 dieneephalon. Although a number of authors have written of nuclei 



