462 CONJUNCTIVA AND SCLEEOTIC, 



The larger nerve trunks, everywhere composed of somewhat 

 separated doubly contoured nerve fibres, exhibited after under- 

 going manifold division, and after running for a greater or less 

 extent forward, the most distinct connection with the already 

 mentioned longitudinally running axis cylinders, with which 

 they are continuous in such a manner that the ultimate trunk- 

 lets, composed of two doubly contoured fibres, lose their medulla 

 at the point of division. This suppression of the medullary sheath, 

 as well as the course of the pale fibres towards the line of demar- 

 cation of the connective-tissue and cartilaginous layers, could 

 be satisfactorily demonstrated by altering the focussing. Owing 

 to repeated division, there is a rapid increase in the number of 

 the axis cylinders, just like that which has been already de- 

 scribed as occurring in the subepithelial plexus of the conjunc- 

 tiva. The fibres were observed to become progressively finer, 

 and were ultimately lost, after pursuing a long course, and 

 whilst of extremely small diameter, in the substance of the 

 fibrous tissue very near the cartilage. In this course they 

 frequently crossed one another, but never communicated, and 

 thus formed a peculiar kind of plexus ; their extremities were 

 marked, not by any increase in diameter, but rather by a 

 diminution, since they simply ran out to a point. Through- 

 out their whole course they were frequently seen to be in 

 contact with the numerous connective-tissue corpuscles dis- 

 tributed through the fibrous bands, but their extremities were 

 never, in spite of the most careful examination, observed to be 

 directly continuous with the processes of the latter. 



In the Pigeon and Fowl Helfreich found no traces of nerves 

 having an analogous distribution to those above described in 

 the Frog. Commencing from the plane of insertion of the recti 

 muscles, however, were trunklets running forward throughout 

 the whole circumference of the fibrous capsule ; but these, on ac- 

 count of the absence of division, as well as on account of their 

 relations generally, he regarded as nerves that are merely 

 traversing the tissue on their way to the ciliary muscle, iris, 

 cornea, etc. They had a similar destination in the sclerotic of 

 the Mouse and Eat, in which animals the procurement of good 

 specimens was rendered very difficult on account of the mani- 

 fold and intimate connections between the sclerotic and choroid. 



