458 CONJUNCTIVA AND SCLEROTIC. 



suddenly loses its medullary sheath, and, ascending vertically 

 again, bends at right angles to its former course to enter the 

 subepithelial plexus of pale fibres, in which it runs for some 

 distance, as may be easily demonstrated in more obliquely 

 made vertical sections. 



Reference must not be omitted to those pale fibres which 

 enter the tissue on the same plane as the larger vascular and 

 nervous trunks, and are characterised by a very sinuous course, 

 and by preserving their original direction for a considerable 

 distance. In consequence of this they only gradually pass for- 

 wards, and then entering the general subepithelial nervous 

 expansion, can no longer be separately followed. In this 

 course they often come into relation with the larger vascular 

 trunks, immediately around and on which they form numerous 

 plexiform loops, and run, sometimes for long distances, upon 

 the vessels themselves. But as these relations can only be ob- 

 served in preparations of moderate size, we must often abandon 

 the attempt to follow them out. Nevertheless, Helfreich was 

 successful in a large number of cases in following them upwards 

 towards the epithelium, and saw them enter the general plexus 

 found beneath this. During their long course they exhibit 

 numerous varicosities and many clusters of nuclei. 



As already mentioned, the trunklets of the last order are 

 composed of two, or at most three, doubly contoured fibres. 

 The latter lose their medullary sheath at the point of their 

 ultimate division, but not previously, during their common 

 course. A nucleus usually occupies the angle of division, and 

 this shows also a slight varicose enlargement, at which point 

 the pale fibres commence. 



These fibres are of extraordinary length, and a single fibril 

 may often be followed through several fields of the microscope ; 

 they usually run in a straight direction, and consequently only 

 present slight and occasional loopings, or a gradually bending 

 upwards to a higher level, crossing and interweaving with the 

 t capillary plexus. The number of these non-medullated fibrils 

 as they run upward through the capillary plexus is extraordi- 

 narily great, so that the total number of the fibres running 

 between the capillaries and immediately subjacent to the 

 epithelium exceeds many times that of the fibres present in the 



