NER VE- TISSUE. 4 5 



devoid of a primitive sheath. There are no ampullae in the living condition. Do not pre- 

 serve this preparation. 



NON-MEDULLATED NERVE-FIBRES. 



These may be detected in an ordinary nerve and studied there, but it is better to select a 

 nerve containing these or sympathetic fibres in large quantities. The sympathetic nerve from the 

 neck of a rabbit may be selected, but it is far better to have a larger nerve. This is easily 

 obtained from the spleen of an ox. Accompanying the branches of the splenic vein are 

 large nerve-trunks, the nerves of the spleen, which contain only a few medullated fibres, the 

 rest being non-medullated nerve-fibres. With scissors cut open the splenic vein, and then the 

 nerve-trunk is easily dissected out. 



PREPARATION. Place the nerve, extended, as for the medullated nerve, in a one per 

 cent solution of osmic acid, and after washing place it in picrocarmine for twenty-four hours. 

 Tease a small fragment in glycerine, and cover. 



EXAMINATION (H). Neglect the medullated nerve-fibres and observe the non-medullated 

 nerve-fibres. They are pale, flat, slightly granular bands which have no myeline, and in their 

 course the oval red-stained nuclei of the primitive sheath are easily seen. Sometimes the nuclei 

 are seen on edge, and at other times on the flat. In this nerve many ' plasma cells ' (p. 20) 

 are found. 



If desired, a fresh nerve may be teased in salt solution, when similar appearances are 

 observable. 



Nerve-cells will be considered with the organs in which they occur. 



SOME PERIPHERAL TERMINATIONS OF NERVES. 



We shall only allude here in detail to the terminations of nerves in striped muscle by 

 means of end-plates, and to the Pacinian corpuscles attached to the ends of certain sensory 

 nerves (p. 46). Other modes of termination will be described in the organs where they occur. 



TERMINATIONS IN STRIPED MUSCLE. 



PREPARATION. This is by no means an easy task. In mammals the best muscles are 

 the straight muscles of the eyeball of a rabbit the muscular part of the diaphragm and any 

 thin muscles such as the intercostals. In the lizard (Lacerta agilis) the end plates may be 

 more easily found. But the best muscles are those which attach the skin to the ribs of the 

 smaller snakes. In any case it is best to employ the following gold method. Snip out very 

 thin pieces of the muscle to be examined, and place them in lemon-juice for five minutes, then 

 wash in water and transfer to a one per cent, solution of gold chloride for twenty minutes or half 

 an hour wash again and place the preparation in the dark for twenty-four hours in a twenty- 

 five per cent, solution of formic acid. After washing thoroughly, to remove the acid, tease 

 out a small piece of the muscle in glycerine, and search with a low power for a nerve-fibre, or 

 trace the outline of a muscular fibre till an end plate is obtained. The axis-cylinder is con- 

 tinued beyond the end plate, and breaks up into fibrils inside the sarcolemma ; their ulti- 

 mate relation to the sarcous substance, however, is unknown. These preparations are difficult 

 to make, and do not keep well afterwards. 



The terminations of nerves in unstriped muscle will be considered under the head of small 

 intestine (p. 71) ', the same methods are applicable as for those of striped muscle nerve-endings. 



