ORIGIN OP THE TRABECULE OF THE OPTIC NERVE. 479 



Researches on the Origin and Development of 

 the Epiblastic Trabeculae and the Pial Sheath 

 of the Optic Nerve of the Frog, with illus- 

 trations of Variations met with in other 

 Vertebrates, and some Observations on the 

 Lymphatics of the Optic Nerve. 



By 



J. T. Oradoii, M.A., 



St. John's College, Oxford. 



With Plates 26, 27. 



Introduction. 



Just over a year ago I began to feel dissatisfied with 

 Asslieton's (1) conclusion that the cells of the optic stalk do 

 nothing more than serve as a conductor for the fibres of the 

 optic nerve. 



As I was aware that Assheton^s (1) opinion had been fully- 

 endorsed by Professor Ryder (8) in the embryological sec- 

 tion of Norris and Oliver's ' System of Diseases of the Bye/ 

 I thought it unnecessary to go any further into the literature 

 of the subject before beginning the present researches, and 

 unfortunately I had finished them before I found that the 

 part of the epiblastic trabeculte that I shall speak of as 

 transverse, had been dealt with by W. Miiller (6), Kolliker 

 (6), Robinson (7), Studnicka (9), and Froriep (3 a). But, as 

 all of these well-known investigators have dealt with the 

 transverse fibrils as though they were the whole epiblastic 

 trabeculae of the optic nerve, instead of being only a part of 



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