154 Journal of Comparative Neurology. 



mixture the contrast between the two kinds is noticeable only 

 upon close inspection and then only as a difference in size. 

 After staining with fuchsin brings out no further difference. 

 The chromatin elements then appear more distinct and more 

 numerous, but both seem equally well supplied. Nor is there 

 a difference in the presence or absence of a small dark colored 

 nucleolus in preparations treated after the copper-hsematoxylin 

 method. The slight chemical difference indicated by the differ- 

 ence in depth of coloring shown by the latter method is, how- 

 ever, supported by a difference in the fibers given off from the 

 cells, as will be seen a few lines further on. 



In similar sections of the brain of a wasp I find but one 

 size in the cells of this region. But two sizes occur in the 

 cockroach according to Flogel ( is) and are doubtless to be 

 found in other forms. But one or two kinds, the cells of the 

 mushroom bodies in the hexapods generally, and of the regions 

 compared with them in Crustacea, are strongly distinguished 

 from nerve cells elsewhere in the brain, and in the whole nerv- 

 ous system for that matter, in being nearly devoid of extra-nu- 

 clear protoplasm. This fact led Dietl to term them ganglionary 

 nuclei, a term that was later altered by St. Remy (90) to the 

 equally characteristic one of chromatic cells. 



Between the tiers of cells fine fibrils and tracheae make 

 their way to the inner surface of the cup, the tracheee also 

 branching among the cells as already described or figured in 

 Plate XXII (fig. 29). The nerve fibers may be traced, with 

 considerable difficulty, however, to the cells. In bichromate- of 

 silver preparations both cells and fibers easily impregnate and 

 where the section is in the right place or where too many elements 

 have not become darkened, the fibers are readily traced into the 

 fibrillar substance forming the calyx-cup (fig. 18, PI. XXI), 



Here the fibers from the larger or marginal cells break up 

 into a series of fine branches that again subdivide and produce 

 a bushy or arborescent formation that reaches to the outer wall 

 of the calyx and of which the drawing (fig. 18, PI. XXI), al- 

 though made with a camera, can give but a poor conception. 

 The preparation from which this drawing was made is one of 



