MUSCLE-TISSUE. 



273 



direction along the fibers ; the branches, repeatedly bifurcating 

 and connecting, produce a plexus in the perimysium. From this 

 plexus arise the terminal nerve-fibers, each of the muscle-fibers 

 being supplied with at least one fiber. In some amphibia, the 

 medullated nerve-fiber penetrates the sarcolemma and divides 

 into a number of longitudinal axis fibrillae on the surface of the 

 muscle. In most animals 

 there has been observed a 

 terminal disk, the " motor 

 hill" of Doyere. This is 

 a finely granular discoid, 

 slightly elevated formation, 

 curving with the surface of 

 the muscle-fiber, with a num- 

 ber of faintly outlined nuclei. 

 The medullated nerve-fiber 

 on reaching the hill becomes 

 deprived of its myeline in- 

 vestment, while the elastic 

 myeline sheath (Schwann's 

 sheath) fuses with the sarco- 

 lemma, so that the motor 

 hill, according to the views 

 of most observers, lies un- 

 derneath the sarcolemma. 

 W. Krause maintains its 

 position outside the sarco- 

 lemma (see Fig. 111). Kiihne 

 has found a broad layer of 

 fused medullated nerves 

 upon the hill in all higher 

 animals. The axis cylinder 

 of the nerve-fiber connects 

 directly with the delicate 

 bioplasson reticulum within 

 the motor hill, and this is 



A, artery ; V, vein. Magnified 800 diameters. 



again connected by delicate 



filaments to the next sarcous elements. Thus a continuous con- 

 nection between the nerve and the muscle is established by bridges 

 of living matter. Some medullated and perhaps sensorial nerve- 

 fibers branch in the perimysium without entering the formation 

 of the motor hills. 

 18 



FIG. 117. STRIPED MUSCLE OF CAT. 

 INJECTED. 



