Siriu'Jui'c of Sriiooth Muscle. 517 



other. Typically, however, the nucleus is always surrounded by 

 niyofibrillae: 



The nuclear membrane consists of a heavy network of linin studded 

 with fine chromatic granules. It is of smooth and even contour. 

 Inside the nucleus is a delicate linin reticulum, with a slightly 

 coarser but still finely meshed chromatic reticulum. Both linin and 

 chromatin are composed of fine granules, Figs. 5, 24, 27, 82, 90. 

 From one to several plasmasomes are present. 'No spiral strand of 

 chromatin, such as is described by Miinch, lOOo, was found in rest- 

 ing muscle. 



IsTumerous granules are present in the reticular protoplasm imme- 

 diately surrounding the nucleus, but none of them could be identified 

 as centrosomes, such as were descrilicd l)y Tvenhossek, 1899. 



4. Interstitial connective tissue. 



The interstitial connective tissue of adult smooth muscle resembles 

 as a rule ordinary areolar tissue. The connective tissue cells in some 

 cases seem to retain their ju'imitive relation to the j)rotoplasmic 

 syncytium, Fig. 14 I). I'he collagenous fibers may be arranged in 

 a loose reticulum, Figs. 2, 24, .'JO, or as a denser reticulum. Figs. 15, 

 16. Wliere the muscle cells ]\v very close together the collagenous 

 fibers may be crowded into thiu uiendiranes. Such membranes have 

 been described by Watney, 1^7U, hy ITeidenhain, 1900, and were 

 figured by the author in a previous paper (1), 1907. 



The collagenous fibers were stained by Mallory's anilin-blue con- 

 nective tissue stain and Van Gieson's stain. With either of these 

 stains they appear extremely fine, united in may places into bundles, 

 I'igs. 28, 29, 34. Flere and there in the adult they still appear to run 

 through the ]n-otoplasm of the connective tissue cells or even in among 

 the myofibrillse. 



The elastic fibers are rather coarse, homogeneous structures, which 

 vary greatly in thickness, Figs. 8, 12, 15. They frequently branch 

 and anastomose. They lie for the most part close beside the muscle 

 fibers. Rarely some of them are embedded in the muscle protoplasm 

 among the peripheral myofibrilhp. The intimate relations of colla- 

 genous and elastic fibers and the mvofibrillje are clearlv understood 



