No. 5-] HABENULAR TRACTS OF ACIPENSER. 



231 



12 to 48 /M. The dendrites present the same appearance as 

 those of the pyramidal cells. The axis cylinders arise from the 

 cell bodies or from the basal part of the dendrites, are medium- 

 sized, smooth fibers of uniform diameter, give off few and short 

 or no collaterals, and enter the tractus strio-thalamici. Many 

 cells of this description are scattered among the pyramidal cells 

 of the internal nucleus and some of them have a pyramidal 

 form, so that it is sometimes difficult to distinguish between 



Codtx 



FIG. j. Diagrammatic frontal section of the fore-brain through the anterior commissure. Scale as 

 in Fig. 2. 



the two types of cells. In a single series in which the axis 

 cylinders are very well impregnated, I have in a few cases 

 found the two kinds of cells side by side in the same section. 

 It should be added that the cells in the ventral part of the stri- 

 atum are smaller, have usually only two dendrites, send their 

 axis cylinders into the median portion of the tractus strio- 

 thalamici, and are readily distinguished from the pyramidal 

 cells of the internal nucleus. 



Goronowitsch ('88) describes the appearance of these two 

 nuclei in picrocarmine preparations of the brain of Acipcnser 

 ruthemis. Van Gehuchten ('94) states that in the trout all the 



