116' 



THE NERVOUS TISSUES 



of 

 fibre 



lemma dips in until it is in contact with the axis cylinder. Both 



axis cylinder and neurilemma 

 are continued past the node 

 without interruption. 



The successive nodes 

 Ranvier divide the nerve 

 into interannular 

 Within each interannular seg- 

 ment the medullary sheath, on 

 blackening with osmium tet- 

 roxid, presents clear intervals 

 which penetrate the myelin 

 sheath in such manner as to 

 give the appearance of obliquely 

 disposed clear lines or incisions. 

 These incisures of Schmidt 

 (Schmidt - Lantermann lines) 

 have not been satisfactorily ex- 

 plained and can not be demon- 

 strated in the living fibre, yet 

 they present a constant form 

 and are always present in osmic 

 preparations.* These incisures 

 subdivide the interannular seg- 

 ments of the medullary sheath 

 into medullary segments. 



In preparations of fresh 

 nerve fibres which have been 

 treated with silver nitrate ac- 

 cording to the method of Ran- 

 vier, the solution is found to 

 enter the fibre most readily at 

 the nodes of Ranvier, so that if 

 blackened by exposure to the 

 sunlight, minute +- like appear- 

 ances are seen at each node. 

 By prolonged maceration in 

 weak solutions of silver nitrate 



FIG. 113. NERVE FIBRES. 



A and B, from the sciatic nerve of a 

 rabbit, isolated by teasing, and viewed in 

 profile ; (7, a group of nerve fibres in tran- 

 saction, from the sciatic nerve of a dog. 

 a, neuraxis ; &, neurilemma projecting be- 

 yond the torn end of the fibre ; d, nucleus ; 

 ft, endoneurium or fibrous sheath of Henle ; 

 J, Schmidt-Lantermann lines ; n, nodes of 

 Ranvier. Osmium tetroxid. A and .B, 

 x 670 ; (7, x 900. 



* Schmidt originally considered them to be the optical expression of folds in 

 the outer fibrous coats. Lantermann and others have shown that they are 

 within the neurilemma. 



