THE EMBRYOLOGY OF THE EYE. 6l 



into more or less distinct bundles, as the 

 connective-tissue septa do later. 



In a transverse section of the nerve we find 

 fibres in every portion, but grouped into larger 

 and more distinct bundles in the centre. 



The cells among the fibres throw out lateral 

 processes which anastomose so that a sort of 

 loose membrane is formed grouping the fibres 

 into bundles (Fig. i8, A). On the surface of 

 the nerve there is a layer of similar cells (Fig. 

 1 8, B) which have a large, paler, round nu- 

 cleus, and well-marked processes, the longer 

 ones extending into the nerve, the shorter ones 

 joining the branched and spindle-shaped meso- 

 blastic cells (Fig. i8, C), which are beginning 

 to form a sheath about the nerve. 



At this stage the cells of the mesoblast and 

 the branched cells of the neural epiblast bear 

 a remarkable resemblance to each other, and 

 most authors have considered the cells in the 

 nerve to be mesoblastic. At this stage, how- 

 ever, no mesoblastic cells can be seen to 

 extend into the nerve, and the cells of the 



