NERVES OF VOLUNTARY MUSCLES. 



351 



amphibia (fig. 415), where there is no continuous granular bed with clear nuclei 

 imbedded in it, and the ramifications of the axis-cylinder are extended over a much 

 larger proportionate area of the fibre than in reptiles, birds, and mammals, so 

 that the termination of the nerve is far less localised. The branches of the axis- 



Fig. 414. TERMINATION OP A NERVE IN 



A MUSCULAR FIBRE OF THE LIZARD 



(Lacerta viridis). (Ranvier. ) Highly 

 magnified, 



h, sheath of the nerve-fibre ; b, 

 bifurcation of the fibre ; e, node ; m, 

 short segment beyond the node ; r. ter- 

 minal ramifications of the axis-cylinder ; 

 n, nuclei on the branches of the axis- 

 cylinder ; ', nuclei in the granular sub- 

 stance of the end-plate. The granular 

 substance lies in the intervals between 

 the branches of the axis-cylinder ; it is 

 not seen in this figure. 



Fig. 415. NERVE-ENDING IN MUSCLE OF FROG. (Kuhne.) 



a, one of the branches of the medullated fibre passing within the sarcolemma ; b, b, granular pear- 

 shaped nuclei of the arborisation ; c, c, nuclei of sheath ; e, e, muscle-nuclei. 



cylinder run for a short distance parallel with the axis of the fibre between the 

 sarcolemma and muscular substance, terminating abruptly by rounded extremities. 

 They have here and there slight enlargements, connected with which are seen, as 

 in the end-plate of the lizard, granular pear-shaped nuclei (Z>), entirely different in 

 appearance from the proper nuclei of the muscle (e). In other animals, e.g., in 

 snakes, there is a tendency for the branches of the ramification to become dilated 

 at their termination into bulbous enlargements, which in a well-stained preparation 

 gives an appearance like that of a bunch of berries. Many other variations are met 

 with, but in no case is there a departure from the general rule that the ultimate 



