OF DENISON UNIVERSITY. 
73 
it. The remaining zone of gray is the cortex, and is connected by fibre 
and cell chains with at least the two median layers. 
In just what way the cortex is related to the optic tract is difficult 
to determine. In some places there is still a superficial fibre tract 
corresponding to the stratum zonale. The outer layer of the nates 
contains, as already said, radiating systems of fibres and cells. Of the 
latter four kinds are recognized. First, a system of superficial pyra- 
midal cells, with their bases peripheral, each with a single process 
passing toward the center. These cells measure .017-. 02 mm., with 
a nucleus .006 mm. in diameter. The protoplasm stains very faintly 
and the cell gives off a process which may unite with cells of 
the fourth sort. It must be left at present undetermined whether these 
cells are really nervous or not. We could not be certain that basal 
processes connect them with the superficial fibre zone. Second, very 
numerous nutritive cells of the usual type are scattered irregularly. 
Third, nucleated cells of the walls of the blood vessels differentiate 
strongly. Fourth, elongate, bipolar, fusiform cells, .013 mm. long 
by .003 mm, wide. Below these, and apparently connected with 
them, are much larger cells of somewhat pyramidal form, with a single 
peripheral process, blunt proximal extremity with several processes, and 
a large nucleus. These cells measure .024-. 02 7 mm. in length by 
.01-.013 mm. in width. Fig. 6, Plate XIX, is a semi-diagramatic illus- 
tration of the cells of the superficial layer, as seen in longitudinal sec- 
tion (VII-g-2) under the one-fifth inch objective. 
(Consult in this connection Tartuferi^ Sulk Anat. Minut. dell’ 
Eminenze Bigem., etc., in Revista Sperimentale, 1879, Gajiser, Die 
periph. u. cent. Anordnung d. Schnervenpaare u. d. Corpus Bigem. 
Ant., Archiv. f. Psychiatrie, Bd. XIII., Nonakow, Die Beziehung d. 
sogenannt. Sehsphaere z. d. infracorticalen Opticuscentren, etc. ibid, 
Bd. XIV, and Bello nci^ Ueber d. centrale Endigung des Nervus Op- 
ticus bei d. Vertebraten. Zeitsch. f. w. Zook, Bd. XLVII.) 
At the medio-ventral aspect of the sections which display the en- 
trance of the third nerve roots, Meynert’s bundle has assumed the 
longitudinal direction, forming a transversely-cut tract between the 
roots of which there are over one dozen bundles on either side. In 
sections farther caudad than Fig. i, Plate IX, the ventricle of the optic 
lobes vanishes without divaricating. The non-appearance of the col- 
liculi, as seen in lower vertebrates, is to be explained as due to this 
fact, i. e., the substance of the colliculi fused with the sub-natal gray 
