Fig. 13. A portion of the niuoiitracted luuscularis niucoste of the small 

 intestine of pig to show tiie continuity from cell to cell of both granular 

 protoplasm and myofibrilljv, through end anastomoses. The large amount of 

 granular protoplasm and the few peripheral myofibrillae give the tissue the 

 appearance of primitive muscle — a., protoplasmic anastomosis ; i. c, inter- 

 stitial connective tissue ; g. p., granular protoplasm ; c. mf., coarse myofibrillae. 

 Gilson's fluid. Iron-hjiematoxylin-eosin. x l'<^60- 



Fig. 14. From the same region as Fig. 13, but showing in addition anas- 

 tomoses between granular protoplasm of muscle cells and that of connective 

 tissue cells (b.). The whole tissue is distinctly syncytial — g. p., granular 

 protoplasm ; p. s., protoplasmic syncytium ; c. mf., coarse myofibrillae ; c. f., 

 collagenous fibers. Gilson's fluid. Iron-hfematoxylin-eosin. X 1760. 



Fig. 1.5. Section through the circular muscle coat of the small intestine of 

 adult pig, showing the syncytial structure of the tissue. This material was 

 slightly contracted, probably by the fixative, so the nuclei are oval instead 

 of rod shaped, although no distinct contraction nodes are present — a., myo- 

 fibrillje. continuous from cell to cell ; g. p., granular protoplasm ; e. f., elastic 

 fibers : f. mf., fine myofibrilhie. Gilson's fluid. Iron-hiematoxylin. x I'J'SO. 



Fig. 10. Cross-section of muscle from the same region as is shown in Fig. 15. 

 Each muscle cell contains a large number of fine myofibrillae, which in the 

 cross-section appear as fine dots — mf., myofibrillre; i. c. interstitial connective 

 tissue ; e. f.. elastic fibers. Gilson's fluid. Iron-h;iematoxylln-eosin. x 1380. 



Fig. 17. Cross-section through muscle similar to that shown in Fig. 13. 

 Figs. 13-17 are all drawn from the same section. The peripheral arrangement 

 of fibrilltp as "Grenzfibrillen" is shown in Fig. 17 — i. c, interstitial connective 

 tissue; g. p., granular protoplasm; c. mf.. coarse myofibrilhie. Gilson's fluid. 

 Iron-hiematoxylin-eosin. X 1760. 



Fig. 18. Portion of a partially contracted muscle flber from the carotid of 

 ox. showing the varicosity of the myofibril hie in beginning contraction. The 

 coarser myofibrillae are in the main black, the finer, red — t. mf., thickening of 

 a coarse myofibrilla. Zenker's fluid. Iron-haeniatoxylin-eosin. x 1380. 



Fig. 19. A portion of a fiber from the large intestine of dog to show the 

 peripheral position sometimes taken by the nucleus — c. nu., contracted nucleus ; 

 c. n., homogeneous appearing contraction node ; i. s., fibrillated internodal 

 segment. Zenker's fluid. Hansen's haematoxylin-eosin. X 520. 



Figs. 20-22. Portions of muscle from the circular layer of the contracted 

 large intestine of dog. The intestine was contracted from exposure to the air. 

 The contraction nodes (c. n.) in all three sections are apparently homogeneous 

 and are stained very inten-sely in eosin. The internodal segments are lightly 

 stained and show the myofibrillae distinctly. The connective tissue (c. f.) is 

 condensed at the contraction waves. The nuclei in the internodal segments are 

 (Continued on next page.) 



