Jelliffe, Cytology of -the Brains of Some Amphibians. 1 5 1 



oform styrax from the liquidambar seems a promising medium 

 as it brings out quite sharply the chromophihc granules. Its 

 high refractive index should be born in mind. 



DESCRIPTION OF THE CELL STRUCTURES OF NECTURUS. 



Spinal Cord. — All of the cells are clustered about the central 

 canal which is bordered by two or three rows of ependyma cells 

 whose nuclei alone are stained. These measure .075 mm. in 

 diameter; nucleus .003 mm. in diameter. Around these cells 

 is an irregular mass of nuclei which collectively approximate a 

 winged appearance. At the angles of the wing, or, if homol- 

 ogous, the horns, especially the ventral horns, there is a collec- 

 tion of larger cells, the nuclei in these being twice the diam- 

 eter of the others. Some of these are provided with a faint 

 fringe of blue staining cytoplasm about the nucleus but in none 

 of the specimens examined were there any distinct traces of 

 chromophilic granules. 



The rest of the nuclei (cells) have about the same diameter 

 and show an intricate reticulate structure, as do those clustered 

 about the central. canal. 



Medulla. — Passing into the medulla, no changes of note 

 were seen. 



At about the level of the glosso-pharyngeal nucleus a num- 

 ber of larger triangular pyramidal cells was seen. These aver- 

 aged about .035 mm. in diameter, and showed indistinct chro- 

 mophilic granules of an irregular character, some of which radi- 

 ated out in the direction of what would appear to be dendrites. 



The larger cells making up what appeared to be the motor 

 nucleus of the VII nerve were of much the same character ; 

 they averaged .04 mm. and their nuclei were large — .037 mm. 

 In these, faint irregular groupings of stained material approxi- 

 mating the typical chromophilic granules were to be made out. 



The motor nucleus of the V nerve showed analogous con- 

 ditions ; here the ganglion cells averaged slightly smaller. 



Passing into the mesencephalon at about the level of Kings- 

 bury's commiss. optici tecti a number of larger cells were found 

 of peculiar shape. These were more or less square in general ap- 



