93 



Th8 nucleus is a rouaiei, centr^lLy locHtei boiy, filling 

 the larger part of th? mass of the cell. The cytoplasii holis 

 a few tii^roid-boiies of small size, an eviieace of a loi« oP'ier 

 of metabolio activity in this type of cell. Pig. 52, m. n, , exhib- 

 its what letails of internal organization are \^isible under 

 the highest amplification. 



The part which the neurones of this layer take in the 

 physiology of the optic ter:nination may be inferrei witn some 

 degree of certainty. The dense tangle of dendrites just be- 

 neath the incoming optic fibres constitute a large surface for 

 purposes of reception. The spreading axones in the layer be- 

 neath afford, with the neurones there, a physiological nexus 

 of some superficial extent, possible paths of association, if 

 ne choose to apply the term here. 'We will returi to this sub- 

 ject in the following subsection. 



i. The Deeper Veurones.-- This layer is thicker than 

 both the preceding ones put together. The neurones are less 

 closely crowded than those of the middle layer, and they lie 

 in groups between the bundles of optic fibres passing downward 

 to the stratum meduUare profundum (Pig. 21,d. n. ). 



The neurones which give character to this layer are long- 

 drawn-out, the dendrites extending nearly to the external sur- 

 face of the brain, and the axone reaching well toward the lim- 

 itans interna. Pig. 83 shows a typical neurone considerably 

 enlarged. The cell-boiy is spindle-shapei or oval in outline. 



