THE PROTOPLASMA AXD THE CELL. 



19 



We will add one more example of a 

 widelv diffused cell transformation ; wc 

 allude to the transversely striated volun- 

 tary muscle. 



This, a thick, cylindrical fibre, not 

 unfrequently of considerable length, 

 consists of a contractile, longitudinal 

 and transversely striated substance. In 

 the outer portions of the latter lie 

 numerous nuclei with adherent proto- 

 plasma remains. It is surrounded by 

 a hyaloid sheath. The whole, how- 

 ever, arises from a single cell (Fig. 27). 

 This (a), with a continual increase of the 

 nuclei, grows into a thread ; the proto- 

 plasma is transformed into the longitudi- 

 nally and transversely marked substance 

 (V) ; only a scanty remnant surrounds the 

 nucleus, forming it into a rudimentary 

 cell, and the homogeneous covering of 

 the thing is derived from a transforma- 

 tion of the adjacent connective tissue. 



The examples presented may suffice. 

 They show, at least, how the most het- 

 erogeneous may result from what was 

 originally similar, through subsequent 

 cell metamorphosis, and they attest the 

 high signification of the cell in the structure of the organism. 



FlG. 27. — Development of 

 the transversely striated mus- 

 cular fibre (sheep embryo). 



