CONTRACTILE FIBRE-CELLS. 63 



CONTRACTILE FIBRE-CELLS. 



WE are especially indebted to the recent investigations of 

 Kolliker* for a more accurate knowledge of those histological 

 elements which have hitherto been included in their aggregation 

 in the animal body under the name of organic or smooth muscular 

 fibres. These cells commonly appear in the form of long fusiform 

 narrow fibres, with finely attenuated extremities, frequently also in 

 that of elongated, quadrangular, or club-shaped plates, whose mar- 

 gins are occasionally fringed. The majority exhibit, especially when 

 acted upon by acetic acid, a prominent nucleus, which is either 

 cylindrical or baton-like. The nucleus appears to be perfectly 

 homogeneous, a nucleolus being scarcely ever found in] it. The 

 substance of the cell occasionally exhibits pale or dark granules, 

 which are partially arranged in rows corresponding to the axis of 

 the fibres, but in other respects this is also homogeneous. It 

 cannot be decided with certainty whether it is surrounded by any 

 special cell- membrane. These fibre-cells form by the lateral juxta- 

 position of their extremities the bundles of smooth muscle which 

 are visible to the naked eye, and occur, amongst other places, in 

 the intestinal canal. Kolliker divides the smooth muscle into the 

 pure and mixed variety, according as the cells are arranged in 

 larger quantities so as to form bundles and membranes, or are 

 merely interspersed amongst other simple tissues; to the former 

 class belong those which have been long known, and in which 

 Henlef first recognised the presence of true fibre-cells, namely, 

 the muscular coat of the lower half of the oesophagus, of the 

 stomach and intestinal canal, the nipple, the bladder, the prostate 

 gland and vagina. The coarser bundles of these muscles are like- 

 wise held together by connective tissue, but they are not so 

 thoroughly intersected by it, and divided into separate fibrillse, or 

 smaller bundles of fibrillse, as the mixed smooth muscles. The 

 latter, which often appear as if they were scattered over connective 

 tissue, embedded, as it were, in the elastic and nuclear fibres, were 

 first shown by Kolliker J to occur principally in the trabecular 

 tissue of the spleen. They have since been discovered in many 

 other compound tissues, which had been known as contractile and 



* Zeitsch. f. wiss. Zool. Bd. 4, S. 48-87. 



t Allg. Anat. S. 576. 



t Mittheilungen der Zurich, naturf. Gesellschaft, 1847. 



