68 THE ESSENTIALS OF HISTOLOGY 



rod-shaped nucleus, which shows the usual intra-nuclear network and 

 commonly one or two nucleoli. The cell-substance is longitudinally 

 striated, but does not exhibit cross- striae like those of voluntary muscle. 

 There appears to be a delicate sheath to each cell. There is a little 

 intercellular cementing substance uniting the cells together, and which 

 can be stained by nitrate of silver. The fibres are collected into fas- 

 ciculi. 



Plain muscular tissue is found chiefly in the walls of hollow viscera ; 

 thus it forms the muscular coat of the whole of the alimentary canal 

 below the oesophagus, and occurs abundantly in the muscular coat of 

 that tube also, although it is here intermixed with cross- striated 

 muscle ; it is found also in the mucous membrane of the alimentary 

 canal ; in the trachea and its ramifications ; in the urinary bladder 

 and ureters ; in the uterus, Fallopian tubes, and ovary ; in the pro- 

 state, the spleen, and muscle of Miiller in the orbit, and in the ciliary 

 muscle, and iris. The walls of gland-ducts also contain it, and the 

 middle coat of the arteries, veins, and lymphatics is largely composed 

 of this tissue. It occurs also in the skin, both in the secreting part of 

 the sweat-glands, and in small bundles attached to the hair-follicles ; 

 in the scrotum it is found abundantly in the subcutaneous tissue 

 (dartos). 



The muscular tissue of the heart constitutes a special variety of 

 involuntary muscular tissue (cardiac), and will be described along with 

 that organ. 



