chap, ix.] STRIPED MUSCULAR TISSUE. 



73 



from other striped muscular fibres in the following 

 respects: (1) They possess no distinct sarcolemma. 



(2) Their muscle corpuscles are in the centre of the 

 fibres, and more numerous than in ordinary fibres. 



(3) They are very richly branched, each fibre giving off 

 all along its course short branches, or continually divid- 

 ing into smaller 



fibres and form- 

 ing a close net- 

 work (Fig. 43A.) A 

 transverse section 

 through a bundle 

 of such fibres 

 shows, therefore, 

 their cross sections 

 irregular in shape 

 and size. (4) Each 

 nucleus of a muscle 

 corpuscle occupies 

 the centre of one 

 prismatic portion \ 

 each fibre and its 

 branches thus 



Fig. 43A. Striped Muscular Fibres of the 

 Heart of Mouse. 



A, Showing the branching of the fibres and their 

 anastomosis in networks ; B, part of a thin fibre, 

 highly ma,nifled, showing the moniliform 

 primitive fihrill:c: c, one primitive flbrilla 

 more highly magnified. 



1 



appear com 



of a single row of 



such prismatic 



portions, and they 



seem separated 



from one another 



at any rate in an 



early stage by a septum of a transparent substance. 



93. Muscular fibres seem either markedly pale 

 or markedly red (Ranvier) ; in the former (e.g., 

 quaclratus lumborum, or adductor magnus femoris 

 of rabbit) the transverse striation is more distinct 

 and the muscular corpuscles less numerous, than 

 in the latter (e.g., semi-tendinosus of rabbit, 



