EXDIXG IX TEXDOX. 



115 



Fis 



IilIMIiT'I 



J!ii 



; <JM(i 



111] 



Fig. 72. — A Frog's Muscular 



Fibre treated with Acetic; 



Acid, magnified o50 Diam. 



(from Kolliker). 



Tlie nuclei ai'c somewhat sliniiil-:. 

 Interstitial granules in longita- 

 diiial rows, here and there. 



TTuclei 01' inusele-corptiscles. — A number of clear oral nuclei 

 are found in the fibres (see p. Ibl, fig. 105, 

 unci fig. lOG c). In mammalian muscles 

 they lie upon the inner surface of the sarco- 

 lemma, but in frogs they are distributed 

 through the substance of the fibre (fig. 

 72). Associated with and surrounding 

 them is a certain amount of granular pro- 

 toplasm, ^yIlich is doubtless connected with 

 the growth and nutrition of the muscle. 

 It shades off at the margins into the 

 ground-substance of the fibre. Both it 

 and the ground-substance are to be re- 

 garded as the remains of the original 

 formative protoplasm of the embryonic 

 cells which oompose the muscle (Max 

 Schultze). In the unaltered condition 

 the nuclei are commonly obscured, but 

 may be made conspicuous by the addition 

 of acetic acid. 



Length and ending cf the fibres. — 

 The fibres composing a muscle are of 

 limited length, not exceeding one inch and a half ; and accordingly 

 in a long fasciculus a fibre does not reach 

 from one tendinous attachment to the other, 

 ])ut ends with a rounded extremity, invested 

 with its sarcolemma, and cohering with neigh- 

 bouring fibres. Unless when either is fixed 

 to a tendon, both extremities of the fibre 

 terminate in the way described, so that it 

 has a long cylindrical shape. 



Bmnclied fibres. — Generally speaking the 

 fibres neither divide nor anastomose ; but this 

 rule is not without excejition. In the tongue 

 of the frog the muscular fibres (fig. 73) as 

 they approach the surface divide into nume- 

 rous branches, by which they are attached 

 to the under surface of the mucous mem- 

 brane. The same thing has also been seen 

 in the tongue of man and various other 

 animals ; and the fibres of the facial muscles 

 of mammals have been shown by Busk and 

 Huxley to divide in a similar manner where 

 they fix themselves to the skin. 



Connection with tendons. — As shown by 

 Kolliker, the mode of connection diflFers when 

 the muscular fibres are continuous in a direct 

 line with those of the tendon from that which 

 is observed when the former join the latter at 

 a more or less acute angle. In the first case 

 the tAvo are directly continuous, the muscular 

 filn-e being distinguishable fi-om that of the 

 fil^rous tissue by its striation alone (fig. 74, B). 



Fig. 73. — A Branched 

 Muscular Fibre fri'M 

 the Frog's Tongue, mag- 

 nified 350 DIAM. (fiuiu 

 Kolliker). 



In the second case. 



