310 



OF THE PRIMARY TISSUES OF THE HUMAN BODY. 



Fig. 100. 



has shown that every so-called fibre is either a single elongated cell, or is a fas- 

 ciculus of such cells; each cell having an elongated staff-like nucleus, which 

 is one of its most distinctive characters. Three principal forms of such cells 

 are described by him: 1. Short, rounded, fusiform, or nearly rectangular 

 plates, like those of epithelium, about l-1125th of an inch long, and l-1875th 

 of an inch broad: 2. Long plates of irregular rectangular, fusiform, or club 

 shape, with fringed edges, about l-562d of an inch long, and 1-3 750th of an 

 inch broad : 3. Long, narrow, fusiform, round, or flattened fibres, with pointed 

 terminations (Fig. 100), which are either straight or wavy, from about 1 -612th 

 to l-50th of an inch long, and from 1-562 5th to 1-1 12 5th of an inch in breadth. 

 The first and second of these forms are only found in the walls of the blood- 

 vessels; and the first may be easily mistaken for the 

 cells of epithelium ; the last form is the one which 

 presents itself everywhere else. These muscular 

 fibre-cells are composed of a soft yellow substance, 

 which swells in water and acetic acid, in which last 

 it becomes of a paler color. There is no appreciable 

 difference between the outer and inner parts ; though 

 when treated with acetic acid it would seem as if 

 each fibre-cell had a delicate covering. Their sub- 

 stance is homogeneous, with faint longitudinal stria- 

 tions; and they often contain small, pale granules, 

 sometimes yellow globules of fatty matter. Each 

 fibre-cell has a pale nucleus (sometimes only percep- 

 tible when it is treated with acetic acid, 6), which 

 constitutes its most distinctive character. Its form 

 is peculiar, being like a staff rounded at each end 

 (c); its substance is homogeneous; its length from 

 l-2800th to l-1875th of an inch; and its breadth 

 from about l-25,000th to l-14,000th of an inch. 

 The muscles composed of this form of tissue may be 

 divided (according to Prof. Kolliker) into (A) the 

 pure smooth muscles, which contain no other kind 

 of tissue, such as those of the nipple, the corium, 

 the interior of the eye, the intestinal canal, the blad- 

 der, the prostate, the vagina, the smaller arteries, 

 veins, and lymphatics; and (B), the mixed smooth 

 muscles, which contain, besides the muscular fibre- 

 cells, areolar tissue, and elastic fibres; such are the 

 trabeculae of the spleen and corpora cavernosa, the 

 dartos, the circular fibres of the larger arteries and 

 veins, the long and transverse fibres of the urethra, prostatic duct, Fallopian 

 tubes, and uterus; and in the trachea, bronchi, urethra, inner muscular layer 

 of the testicles, seminal ducts, &c., they change by imperceptible degrees into 

 the first form. 



306. The muscular structure of the Heart is peculiar, in presenting the gene- 

 ral arrangement of the non- striated muscles, as regards the interlacement of the 

 fasciculi and the absence of fixed points of attachment, with the ultimate struc- 

 ture of the striated. The fibres are of smaller diameter, however, than those of 

 the voluntary muscles ; and the striae are less strongly marked, and are less 

 regular. In -the heart, too, is seen more frequently than elsewhere, the subdi- 

 vision and anastomosis of the muscular fibres; which, first observed by Prof. 

 Kolliker (in 1849) in the heart of the frog, has been witnessed by the same dis- 

 tinguished anatomist in the cardiac fibres of Man and of various among the 

 higher animals. No proper gradation can be anywhere traced from the striated 



Fusiform cells of Smooth Muscular 

 Fibre, from the renal vein of Man ; 

 a, two cells in their natural state, 

 one of them showing the staff- 

 shaped nucleus; b, a cell treated 

 with acetic acid, with its nucleus c 

 brought strongly into view. 



