118 THE TISSUE 



of smooth muscle the cells are separated into groups or bundles by 

 connective tissue. Smooth muscle cells may be arranged in a sort 

 of network, the cells crossing and interlacing in all directions/ as in 

 the wall of the frog's bladder. //Again, they may be scattered in small 

 groups or singly among connective-tissue elements, as in the villi 

 of the small intestine and in the capsules and trabeculce of some 

 glands. 





-' b 



Fig. 59. — Smooth ]\Iuscle from Longitudinal Section of Cat's Small Intestine, show- 

 ing Portions of Inner Circular and Outer Longitudinal Muscle Coats with Intervening 

 Connective Tissue. X350. (Technic 3, p. 129.) a, Transversely cut cells of inner 

 circular layer; in comparatively few has the plane of section passed through the nucleus; 

 d, longitudinally cut cells of outer longitudinal layer. In many of the cells the plane of 

 section has not passed through the nucleus; c, intermuscular septum (connective tissue); 

 d, small artery. 



Voluntary Striated Muscle. — This consists of cylindrical fibres 

 from 50 to 130 mm. in length and from 10 to ioo,« in diameter. 

 Generally speaking, the fibres of greater diameter are found in the 

 larger animals. There is apparently no relation between the size of 

 the muscle and either the length or diameter of its component fibres. 

 There is also no relation of length to diameter, within the same 

 muscle, fibres of many different sizes intermingling. 



Each muscle fibre consists of (a) a delicate sheath, the sarcolemma, 

 enclosing (b) the muscle substance proper, in which lie (c) the muscle 

 nuclei. 



The sarcolemma is a clear, apparently structureless, very elastic 

 membrane, which adheres so closely to the underlying muscle sub- 

 stance as to be indistinguishable in most preparations. i| In teased 

 specimens it may frequently be seen at the torn ends of the fibres 

 (Fig. 60). 1/ In staining reaction it differs from both white and elastic 

 tissue and is apparently to be considered a distinct cell membrane. 



The muscle substance consists of ergastoplasm (fibrillce) and 



