MUSCULAR TISSUE. 



135 



portion of the cell substance (M. Heidenhain, Schaper, Benda). 

 These fibrils have a longitudinal course, and probably run the en- 

 tire length of the cell ; whether they branch and anastomose must 

 be regarded as an open question. In the interior of the cell sub- 

 stance there are found much finer fibrils, which branch and anasto- 

 mose. Between the fibrils there is 

 found a homogeneous substance, 

 which we may know as the sarco- 

 plasm, in which granules are often 

 seen, situated at the poles of the 

 nuclei. It is generally stated that 

 nonstriated muscle-cells are united 

 into membranes and bundles by a 

 small amount of intercellular cement 

 substance which may be darkened by 

 silver nitrate. Recent investigations 

 have, however, revealed the fact that 

 nonstriated muscle-cells are encased in 

 delicate connective membranes, which 

 membranes unite to form compart- 

 ment-like spaces, of fusiform shape, in 

 which the muscle-cells are found. 

 These membranes are not to be re- 

 garded as cell-membranes sarco- 

 lemma since one membrane serves 

 the sheath for two contiguous 



Nucleus. 



Protoplasm. -- 



as 



muscle-cells (Schaffer, v. Lenhossek, 

 Henneberg). The existence of such 

 membranes is clearly shown in invol- 

 untary muscle tissue subjected to 

 trypsin digestion. In such preparation 

 stained in iron- lac -hematoxylin it 

 may be observed that the membranes 

 are not complete, but are fenestrated, 

 showing a varying number of round 

 or oval openings (Henneberg). The 

 membranes are also clearly shown in 

 tissue fixed in corrosive sublimate and 

 stained in Mallory's differential con- 

 nective-tissue stain, the membranes 

 showing as delicate blue lines while 

 the muscle-cells are stained of a red 

 or orange color. (See Fig. 92.) Ac- 

 cording to certain observers (Kultschitzky, Barfurth), nonstriated 

 muscle-cells are thought to be joined by intercellular, protoplasmic 

 bridges. It may, however, be clearly shown that such intercellular 

 bridges are artifacts, due to peripheral vacuolization and to shrinkage 

 of the muscle-cells (Schaffer, v. Lenhossek, Henneberg). What 



Fig. 92. Nonstriated muscle 

 from the intestine of a cat. X 3- 

 a, Isolated muscle-cell ; b, from 

 cross-section of nonstriated muscle, 

 stained after Mallory's differential 

 connective- tissue stain. Observe 

 the apparent difference in size of 

 the cross-cut cells; four of the cells 

 show ( nuclei ; the black lines separ- 

 ating the cells represent the connec- 

 tive-tissue membranes. c, Cross- 

 sections ;of the connective-tissue 

 membranes separating involuntary 

 muscle-cells ; d, an area showing 

 so-called intercellular bridges; they 

 are attached to the connective tissue 

 membranes surrounding the cells 

 (Mallory's differential connective- 

 tissue stain). 



