Fig. 35. Portion of a muscle fiber from the contracted large Intestine of 

 dog, showing two small contraction nodes (c. n.). The myoflbrillte run con- 

 tinuously from internodal segment to internodal segment through the con- 

 traction nodes, apparently thickening in the region of the nodes, (t. mf.) 

 shows such a thickening — r. nu., a resting nucleus; c. f., collagenous fibers. 

 Zenker's fluid. Iron-hsematoxylin-eosin. X 3000. 



Fig. 36. Is taken from the same section as Fig. 35 and shows similar 

 structure. The contraction nodes are wider than those shown in Fig. 35. 

 Zenker's fluid. Iron hsematoxylin-eosin. x 3000. 



Fig. 37. Cross-section of a portion of the circular muscle coat of the 

 intestine of dog. In the contraction wave (c. w.) the thickening of the fibers, 

 the change in staining reaction, the clumping together of the nuclei, along 

 with the shortening and thickening of each nucleus, ai'e clearly shown — 

 r. nu., resting nucleus ; c. nu., contracted nucleus ; c. n.. contracticm node. 

 Zenker's fluid. Del a field's hjiematoxylin-eosin. X §80. 



Fig. 38. Is taken from the same section as Fig. 35 — c. n., contraction node 

 deeply stained so that no myofibrilliTp show ; i. s., internodal segment ; c. mf., 

 coarse myofibrilla thickening as it enters the contraction node. Zenker's fluid. 

 Iron-hfematoxylin-eosin. x 3000. 



Figs. 39-40. Drawn from the same section as Fig. 35. Portions of muscle 

 fibers showing beginning contraction nodes (c. n.) with the myofibrillje enlarged 

 in the contraction nodes (a, b) — t. mf., thickened myofibrillje. Zenker's fluid. 

 Iron-haematoxylin-eosin. x 3000. 



Fig. 41. A group of myoflbrilliie from a partially contracted muscle filier 

 in the large intestine of dog, showing numerous enlargements of the myo- 

 fibrillse — t. mf., thickened myofibrillse. Zenker's fluid. Iron-haematoxylin. 

 X 3000. 



