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Elementary Biology. 



involuntary from the fact of its occurring in situations 

 where movement is outside the dominion of will, consists 

 of cells less far removed from their typical condition. The 

 protoplasm is longitudinally striated, suggesting the differ- 

 entiation into nbrillae which we have studied in the striped 

 muscle-cell, and a delicate envelope is present correspond- 



FIG. 133.- STRIPED MUSCLE FIBRES. (Quain.) 



B 



A, portion of a muscle fibre ; n, part of the same teased, showing groups 

 of fibrils, a, b, c, and ultimate fibrillse, d, d. 



ing to the sarcolemma. The cell possesses an elongated 

 nucleus lying centrally in the protoplasm. 



In the case of both striped and non-striped muscle the 

 cells are bound together by an intercellular cement into 

 elementary bundles, or fasciculi, which are again collected 

 into larger bundles. Both large and small bundles are held 



