22 THE ELEMENTARY TISSUES 



distribution may be outlined as follows: (i) It is found in the 

 digestive tract from the middle of the esophagus to the anus. 

 (2) in the capsule of the pelvis of the kidney, (3) in the trachea 

 and bronchi, (4) in the ducts of glands, (5) in the gall-bladder, 

 (6) in the vas deferens and seminal vesicles of the male repro- 

 ductive organs, (7) in the uterus, vagina and oviducts of the 

 female reproductive organs, (8) in the blood-vessels and lym- 

 phatics, (9) in the iris, ciliary bodies and eye-lids and (10) in 

 the hair follicles, sweat glands, and skin of the scrotum and in 

 some other places throughout the body. 



The structural unit of smooth muscle is the fiber-cell, which 

 is a delicate spindle with its nucleus usually situated nearer one 

 end than the other. The nuclei of the fiber-cells are usually 

 elongated and oval. These fiber-cells are held together by a 

 delicate connective-tissue network which is composed of both 

 white and elastic fibers. Smooth muscle is very poorly supplied 

 with blood-vessels in comparison to striated muscle. The 

 blood-vessels run along the connective-tissue septa and small 

 branches are distributed to the fiber-cells. The lymphatics, 

 also, follow the connective-tissue septa. The nerves which supply 

 the smooth muscle are of sympathetic fibers. 



The Nervous Tissues. 



These tissues will be considered under the chapter on the 

 Physiology of the Nervous System. 



