6 4 



MUSCULAR TISSUE. 



[sect. 29. 



more induced to lay down, as subdivisions of the muscular tissue, 

 1. that of the contractile cells; and 2. that of the contractile 

 fibres. 



§ 29. Tissue of the Contractile Cells, or of the Smooth Muscles. 



The smooth, also vegetative or organic muscles, consist essentially 

 Fig. 24. of microscopic, generally fusiform, rarely 



short and broad fibres — the contractile, or 

 muscular fibre-cells, as they are called by 

 me. Each of these elements, measuring 

 on average 0-02'" to 0-04'" in length, 

 0-002'" to 0-003'" m breadth, has the sig- 

 nification of an elongated cell ; yet, with 

 some few exceptions (muscular fibres of 

 the gravid uterus), presents no differenti- 

 ation of contents and envelope, but consists 

 of an apparently homogeneous, sometimes 

 finely granular, or slightly striated sub- 

 stance, in which a cylindrical (rod-shaped) 

 long cell-nucleus is invariably found in 

 the middle of the fibre. These fibre-cells 

 are united by means of a not directly 



^s^ScarrLiLmefc observable connecting matter, to form 



Magnified 350 times. flat Qr rounc ) ish cordS) the b und l es f t he 



smooth muscles, which are then connected by delicate envelopes of 

 connective tissue and fine elastic fibres, — a kind of perimysium, — 

 to form larger masses, in which numerous vessels, and a relatively 

 small number of nerves, are distributed. 



The chief elements of the smooth muscles consist, chemically, 

 of a nitrogenous substance allied to fibrin, the fibrin of muscle or 

 syntonin (Lehmann), which, so far as is known, is distinguished 

 from the fibrin of the blood only by its not dissolving in nitrate 

 and carbonate of potash, while it dissolves very readily in diluted 

 hydrochloric acid. The physiological importance of the smooth 

 muscles lies in their contractile property, by which they very 

 materially aid in the functions of the viscera, in which, by reason 

 of the shortness of their elements, they can bring about perfectly 

 local changes of form. The development of their elements takes 

 place simply by the elongation of round cells and the union of 

 the cell-membranes and contents to form a homogeneous soft mass. 

 The process of nutrition may be assumed as being energetic in 

 the smooth muscles, as the more recent investigations of the fluid 



Muscular fibre-cells, from human 

 arteries. I . From the arteria popli- 

 tsea; a without, A with, acetic acid 



