9 8 



COMPARATIVE ANATOMY 



time the sarcolemma is formed as a delicate membrane 

 bounding the fibre. Presently cross as well as longitudinal 

 striae make their appearance and invade the whole periphery 

 of. the fibre, the nuclei imbedded in a core of granular 



is. 1 8. 



A, embryonic striped muscle-fibre from the tail of a tadpole, 

 showing the nuclei tin, and the protoplasm p, of the 

 coenocyte from which the fibres are developed. The fibres 

 exhibit alternate dark and light bands, and in the centre of 

 each dark band is a light line, the line of Hensen ; />', 

 cardiac muscle-fibre showing the short branched nucleated 

 cells ; C, a single cell from cardiac muscle-fibre, more 

 highly magnified, showing the cross-striation and the 

 nucleus n, (A original ; B and C from Schafer.) 



protoplasm occupying the centre. Eventually the striation 

 and fibrillation extends to the centre, and the nuclei move 

 outward to take up a superficial position under the 

 sarcolemma. Thus it appears that, although the striated 



