24. Dll. KLEIN. 



smaller branches of this plexus. If we follow, for instance, 

 a small trunk, containing, say only two medullated 

 fibres, we shall see, for a greater or less extent, that neither 

 of the nerve-fibres which sometimes cross each other or wind 

 round each other comes into direct contact with the deli- 

 cate neurilemma (easily recognised by its nuclei) ; but we 

 shall observe, instead, that the one is separated from the 

 other on both sides by a clear interval. 



The more the trunks of the plexus of nerves of the first 

 order divide into smaller trunks, the more we see the nerves 

 ■which lie within them passing into non-medullated fibres. 

 The latter appear as bundles varying in breadth, of fine 

 fibrillse, furnished with variously sized granular swellings at 

 more or less regular intervals, and running, just as has been 

 already shown in the nerves of the cornea, in places simply 

 lying close together and wavy, in other parts twisting round 

 or forming a reticular connection with each other by giving 

 off little lateral threads. The latter relation comes distinctly 

 into view at the three-cornered expansions corresponding 

 to the anastomoses, of the branches of this plexus. The 

 whole bundle is imbedded in a pale sheath, which becomes 

 but little coloured by chloride of gold, and on which we 

 are just able to recognise a striation here and there. The 

 sheath always contains, although not in great numbers, 

 nuclei of an elongated shape. These appear of various size, 

 and are in gold preparations sometimes coloured uniformly 

 dark, with a sharp outline, at other times seen as clear struc- 

 tures with a double contour, and containing in their interior 

 a few minute granules. These bundles of fibrils we shall 

 call nerves of the second order. 



Here we meet with a relation similar to the one which 

 we indicated in the case of the corneal nerves, existing, 

 on the one hand, between these nerves of the second order, 

 and the small trunks of the first order from which they 

 have proceeded ; and, on the other, between the sheath in 

 which they are imbedded and the neurilemma of these trunks. 

 A small trunk of the first order, which, e.g., contains within 

 its sheath only a single medullated fibre, passes over un- 

 divided into a bundle of fine fibrillae ; or, instead, it divides 

 into two or three smaller but similar little bundles, Avhich 

 remain separated in their further course ; or, instead, we see 

 a small trunk of the first order containing two medullated 

 fibred pass abruptly into a combined bundle of the finest 

 fibrils, which in its further course gives off several smaller 

 lateral bundles. 



Where those nerves of the second order originate we may 



