NERVES OF VOLUNTARY MUSCLES. 



appearing to end in small bulbous extremities, but, according to Fischer, do not 

 penetrate the muscular fibres. Motorial end-plates, such as occur in voluntary 

 cross-striated muscle, are not found in the heart. 



The nerves of voluntary muscles terminate for the most part in special 

 expansions, to which the term motorial end-plates has been applied. The term 

 end-organ is however a more suitable one, for, as will immediately be explained, 

 the termination of the nerve is rather of the nature of a flattened ramification than. 

 a continuous plate. 



As was mentioned in the account of the muscular tissue, the nerves in the 

 voluntary muscles form plexuses, of which the branches grow finer and the meshes 

 closer as they advance further into the tissue. The individual fibres, while still 

 associated in small bundles, undergo division (fig. 388), and at length single dark- 

 bordered fibres pass off to the muscular fibres. These nerve-fibres on approaching 

 or reaching a muscular fibre often divide still further. The branches retain their 

 medullary sheath until they reach the sarcolemma, when the white substance 

 abruptly terminates, while the neurolemma becomes continuous with the sar- 

 colemma (fig. 410, s). It would seem that the prolongation of the nucleated sheath 

 of Henle is also continued over the end-organ, which thus receives a double covering 



Fig. 410. NERVE-ENDING IN MUSCULAR FIBRE OF A LIZARD (Lacerta viridis) (Kiihne.) 



(Highly magnified.) 



a, end-organ seen edgeways ; b, from the surface, s, s, sarcolemma (here sometimes termed 

 "telolemma") ; p, p, expansion of axis-cylinder. Beneath this is granular protoplasm containing a 

 number of large clear nuclei and constituting the " bed " or "sole" of the end organ. In 6 the expansion 

 of the axis-cylinder appeal's as a clear network, branching from the divisions of the medullated fibre. 



to which the name telolemma has been given by Kuhne. The axis-cylinder as it passes 

 into the fibre forms a clear localised branched expansion (p p), which lies imme- 

 diately under the sarcolemma, embedded in a layer of granular matter, the " bed " 

 or " sole " of the end-organ, which contains a number of large clear nuclei, each 

 having one or more distinct nucleoli. The termination of the axis-cylinder is not a 

 continuous plate, as was thought by Rouget, but appears when viewed from the sur- 

 face in the form of an arborescent figure (figs. 410 to 415), the branches of which do 

 not, according to Ranvier, anastomose. According to Kiihne the branching figure 

 which is formed by the axis-cylinder is composed of an axial part, staining darkly 

 with gold, and a peripheral part or stroma, which remains unstained. Kiihne regards 

 the axial part as representing the fibrils of the axis-cylinder, but it may be doubted 

 whether the differentiation into axial part and stroma is not due to the shrinking of 

 the axis-cylinder under the influence of the reagent. The appearance of the two 



A A 2 



