218 DE J. 0. WAKELIN BAKRATT. 



the inner aspect of the 3rd nerve, lying near those fibres of the 

 inferior division of this nerve, from among which the short root 

 of the ciliary ganglion arises (cp. fig. 1, sect. 5, and succeed- 

 ing sections). I have made repeated attempts to demonstrate 

 the existence of neuroglia fibres in the amorphous material by 

 Weigert's neuroglia stain, but so far I have been uniformly 

 unsuccessful. The amount of this material varies much. It is 

 sometimes obtrusive from its abundance, while in other cases 

 it is very small in amount, and sometimes transverse sections 

 fail to reveal any trace of its existence. Its presence is much 

 more readily exhibited in transverse than in longitudinal 

 sections. 



Non-meduUated fibres are found in the 3rd nerve, both in the 

 fibrous sheath and in the main trunk among the medallated 

 fibres, but in the latter situation usually quite at the periphery, 

 and in contact with the nerve-sheath. 



The Fourth Cranial Nerve. 



The 4th cranial nerve, like the 3rd nerve, consists at its 

 origin of separate rootlets, which remain in contact with each 

 other, without, however, any close union (fig. 4). The dura 

 mater invests the nerve at about forty millimetres from its 

 superficial origin (fig. 4, sect. 40), when the separate bundles 

 of which it is made up blend together, and the transverse 

 section becomes nearly uniform in aspect, with very few septa 

 (sections 40 to 70), until the nerve approaches to its termination 

 (sections 75 to 85). Very few bundles come into intimate 

 relation with the 4th nerve. A study of a complete series of 

 transverse sections shows that, at any rate in the four nerves 

 upon which the present observations are based, no branches can 

 properly be said to be given off from or to join the main trunk, 

 with the exception of the meningeal branch, which is seen to 

 join the nerve at about thirty millimetres from its superficial 

 origin (fig. 4, sketch of the nerve, and sect. 35). It accom- 

 panies the main trunk for nineteen millimetres, when it 

 perforates the outer sheath, lying first upon the surface of the 

 fibres (fig. 4, sect. 50) ; then passing in towards the centre of 

 the main trunk, and becoming lost at a distance of about fifty-one 



