SKELETAL MUSCLE 93 



thicker cross-pieces, or anipulla?, extend across the fibers and may 

 dilate with blood when the muscle is contracted. 



If a muscle is seriously injured its destroyed ])ortion is re])lace(l 

 by scar tissue, but if the sarcolemma of a fiber is not injured the 

 injured myofibrils are digested and the fiber remaining acts like a 

 myoblast and forms new nuclei and fibrils, possibly also new units 

 by mitosis. 



The manner of attachment of skeletal muscles to tendons is 

 thought by some to involve a continuation of the myofibrils with 

 the collagenous fibrils of the tendon, by others to involve continua- 

 tions of the connective tissue (endomysium) with the tendon. The 

 latter appears to be the more likely association. 



REFERENCES. 



Brinley, F. ,J. 1932. A physiological study of the innervation of the heart 

 of fish embryos, PhysioL ZooL, 5, 527. 



Cardwell, .J. C, AND Abram.son, D. I. 1931. The atrioventricular conduc- 

 tion system of the beef heart, Am. Jour. Anat., 49, 167. 



Carr, R. W. 1931. Muscle tendon attachment in the striated muscle of the 

 fetal pig. Am. Jour. Anat., 99, 1. 



Jordan, H. E. 1934. Structural changes during contraction in striped mu.scle 

 of the frog, Am. Jour. Anat., 55, 117. 



Katznelson, Z. S. 1934. Histogenesis of muscle in Ami)hibia: 1. Develop- 

 ment of striated muscle from mesenchyme in urodeles, Anat. Rec, 61, 109. 



Lewis, M. R., and Lewis, W. H. 1917. The contraction of smooth muscle 

 cells in tissue cultures. Am. Jour. Physiol., 44, 67. 



Lloyd, W. 1930. The form and function of the auriculo-ventricular bundle 

 in the rabbit. Am. Join-. Anat., 45, 379. 



Mather, V., and Hines, M. 1934. Studies in the innervations of skeletal 

 muscle: The limb muscle in the newt, Triturus torosus, Am. Jour. Anat., 

 54, 177. 



Pollister, a. 1932. Mitosis in non-.striated muscle cells," Anat. Rec, 53, 11. 



Zschiesche, E. S., and Stilwell, E. F. 1934. Intercalated discs of the heart 

 of the guinea-pig, Anat. Rec, 60, 477, 



See Appendix for general text references. 



