340 



ELECTRO-PHYSIOLOGY 



CHAP. 



The motor nerve-endings in fishes differ in several respects. 

 Along with such as correspond completely with the " end-plates " 

 of the higher vertebrates (Myxine, Raja ; cf. Eetzius, 53), there are 

 in the same species a proportion of much simpler forms, in which 

 the axis-cylinder is little if at all bifurcated, after losing the 



t; 



FIG. 223. End-plates from muscle-fibre of rabbit (a), guinea-pig (c), rat (&). Gold preparations. 



(Kiihne.) 



medullary sheath, and lies simply along the muscle-fibre, where 

 it is visible as a very large number of knotty varicosities (" end- 

 discs" of Eetzius). Certain amphibians and the higher vertebrates 

 also present innumerable transitions from the simplest forms of 

 ending to the most complicated " branches " and " plates." It is 

 remarkable that a particular type of nerve-ending is sometimes 

 confined to one muscle, or group of muscles, in the same animal. 



