OBSERVATIONS ON THE STEUCTUEE OF THE THIED, 

 EOUETH, AND SIXTH CEANIAL NEEVES. By J. 0. 



Wakelin Barratt, M.D. Lond., F.E.C.S. Eng., Pathologist 

 to the West Biding Asylum, Wahcjleld. (Plates XX VII. - 

 XXXI.) 



In the present paper the structure of the 3rd, 4th, and 6th 

 cranial nerves in the human subject is investigated according 

 to the method already adopted in studying that of the 9th, 

 10th, 11th, and 12th cranial nerves.^ That is to say, the nerves 

 were first dissected out, from their superficial origin to their 

 termination in muscle ; they were then, after hardening, 

 sectioned along their whole length (the sections being 25/x 

 thick) ; finally, a complete series of sections selected at intervals 

 of a quarter of a millimetre were mounted, the sections being 

 always placed in the same position relatively to each other on 

 the slide. From a study of these sections the course and 

 arrangement of the nerve-fibres and the situation and limits of 

 nerve-cells or other structures was ascertained, and the nerve 

 itself reconstructed, knowledge being in this way acquired of the 

 constitution of the nerve studied, over and above that gained by 

 the most careful dissection. 



The staining methods adopted for serial sections included 

 Marchi staining, with or without erythrosin counter-stainiug, 

 carmine staining in bulk, and aniline blue-black staining in bulk. 

 In addition to serial sections, portions of the nerves were 

 stained specially by Nissl's and Cox's methods (for nerve-cells), 

 with methylene-blue and safranine, and by Stroebe's method 

 (in investigating details of structure respecting nerve-fibres) ; 

 and by Weigert's neuroglia-stain (in studying the vestigial 

 structures). 



In all, four 3rd nerves (three right and one left), four 4th 

 nerves (two right and two left), and three 6th nerves (two right 

 and one left) were cut in serial section along their whole length. 



^ Journal of Anatomy and Ph»/.nology, 1898, xxxii. pp. 422-427. Also 

 Arch, of Neurol, of the London. County Asylums, 1899, pp. 537-552. 



