STBtJCTTJKE OF THE SORSE. 12Y 



membranous organ. It consists of three coats — a mucous, mus- 

 cular, and a serous coat. Tlie serous coat only partly invests it, 

 covering the upper half or more of the posterior wall, and being 

 reflected from the sides and apex to the surrounding parts. The 

 muscular coat consists of two layers of smooth, muscular fibers, 

 an external longitudinal one and an inner circular layer, thinly 

 scattered over the body, but denser at the neck, forming the 

 sphincter vesicae. The mucous coat is pink and smooth; it is 

 thrown into wrinkles, except at the trigone, where it is adherent 

 to the muscular layer beneath. 



The ureters are two membranous canals, which convey the 

 urine from the kidneys to the bladder. They have an external 

 fibro-cellular, a middle muscular, and an internal mucous coat 

 lined with epithelium, similar to that of the bladder. 



NERVOUS SYSTEM. 



The ner^^ous system embraces those organs which receive and 

 interpret impressions, stimulating and regulating the vital func- 

 tions. The system is divided into the cerebro-spinal and the 

 sympathetic. The former includes the brain, spinal cord, cer- 

 tain ganglia, motor, and sensory nerves. The motor nerves are 

 supplied to the voluntary muscles; the sensory are distributed 

 to the organs of sense, skin, and other parts endowed with sen- 

 sibility. The sympathetic consists of a series of ganglia and 

 nerves, which supply the involuntary muscular fibers of the 

 uterus, stomach, intestines, ducts, and blood vessels. 



The two systems are so intimately connected with each other 

 that they can hardly be considered as distinct. The sympa- 

 thetic system may be regarded as that portion which supplies 

 the internal organs and blood vessels, having its own central and 

 peripheral organs, like that of the cerebro-spinal. The two sys- 

 tems have free inter-communication, ganglia being placed at the 

 junctions. 



The nerve consists of bundles of nen^e fibers bound together 

 by a common tissue sheath. This sheath surrounds the whole 



