GENERAL HISTOLOGY OF THE NERVOUS SYSTEM. 125 



seen winding in at one end (Fig. 49), covered with a dense coat- 

 ing of connective tissue, and accompanied by a small artery. 

 After penetrating a variable distance, it leaves its medulla and 

 is continuous with a straight fibrillated band that is called the 

 core. It terminates in one or more granular expansions, appar- 

 ently. In two cases, how- 

 ever, I saw the nerve passing 

 through the body, giving off 

 its medulla on entering it, and 

 assuming it again on leaving. 

 This has been observed by 

 Klein, Pappenheim, and oth- 

 ers. Round about the core, 

 forming a series of pretty reg- 

 ularly oval markings, are con- 

 centric tunics. Toward the 

 periphery they are at a pret- 

 ty even distance apart. Be- 

 tween them, applied closely 

 to the tunics, 1 are small ovoid 

 nuclei. The spaces between 

 the lamellae are probably 

 tilled with a clear fluid. In 

 my experience these bodies 

 are not successfully pre- 

 served in glycerine, even after 

 hardening in osmic acid. The 

 chloride of gold may answer 

 better. 



Nerve - terminations in 

 muscle are quite easily seen. 

 It is only necessary to take a 

 bit of muscle from the thigh 

 of a frog just dead, and immerse it in dilute acetic acid, and 

 then in glycerine. When the tissue is thoroughly transpa- 

 rent, as it will be in a few minutes (ten or fifteen), there will 

 be little difficulty in finding a medullated nerve, and then in 

 tracing it into a muscle-fibre. Reaching the sarcolemma, it 



1 According to Schaef er, the nuclei belong to epithelioid corpuscles which cover the 

 tunic on both sides. Practical Histology, p. 134 j Quarterly Microscop. Journ., 

 1875. 



FIG. 49. Pacinian body from the cat's mesentery. 



