286 



A DICTIONARY. 



Ureters. — Two small tubes by which 

 the urine is conveyed from the Iddneys to 

 the bladder. 



Urethra. — A membranous and muscu- 

 lar tube by which the urine is conveyed from 

 the bladder ; it is of considerable length in 

 the horse. 



Urine, Excessive Discharge of. — (See 

 Diabetes.) 



Urine, Incontinence of. — (See Incon- 

 tinence.) 



Uterus. — The womb. The uterus of 

 the mare is very unlike that of the human 

 subject, in whom it consists of one bag, 

 rather of an oval shape, somewhat resem- 

 bling a pear ; but in the mare and other quad- 

 rupeds it has a body and two branches, 

 called its horns. The uterus terminates in 

 the vagina by a narrow portion, called the 

 neck or mouth of the womb. The extrem- 

 ities of these horns have tubes attached to 

 them, which, from the name of the discov- 

 erer, are called Fallopian tubes ; one end 

 of each is expanded, and has a fringed kind 

 of edge : this is named the fimbria of the 

 Fallopian tube. The Fallopian tube is 

 very tortuous in its form ; and that end 

 which proceeds from the horn of the uterus 

 is extremely small ; but the other, which is 

 slightly attached to the ovarium, is consid- 

 erably larger. The ovarium is an oblong 

 body, about the size of a small hen's egg. 

 The ovaria — for there are two of them — 

 are composed of a number of transparent 

 vesiculae, called ova (eggs) ; each ovum is 

 surrounded with cellular membrane; and 

 when the ovum is impregnated and passes 

 into the uterus, it leaves a mark which is 

 named corpus luteum. 



Uvula. — In the human subject, the 

 small flesh-like substance hanging in the 

 middle and back part of the throat, is thus 

 named. In the horse, this is of a very dif- 

 ferent form. The uvula completely closes 

 the opening to the pharynx, though it read- 

 ily yields to the passage of food, or any 

 liquid, toward the gullet ; it prevents, also, 

 the return of anything to the mouth, even 

 the air which is expired from the lungs, un- 

 less it be thrown aside by a violent effort. 



as in coughing. It is on this account that, 

 when the horse is affected with nausea, or 

 has the action of the stomach inverted, — 

 which sometimes happens, though very 

 rarely, — the contents of the stomach will be 

 discharged through the nostrils ; but if the 

 horse happens to cough during the process, 

 some part will be discharged by the mouth. 



Vagina. — The passage from the external 

 pudendum, or shape, to the mouth of the 

 womb. 



Valerian. — The root of valerian is used 

 as an antispasmodic ; its virtues have been 

 underrated by writers on veterinary medi- 

 cine. 



Veins. — The motion of the heart is 

 known to communicate momentum to the 

 blood through the veins. INIr. Percivall 

 says : " We are not to reject the power of 

 the heart altogether, merely because the 

 blood flows with a uniform stream in the 

 veins ; for the absence of pulsation in them 

 is no proof that the motion of the blood is 

 not influenced by the contractions of the 

 heart ; the extreme division which this fluid 

 undergoes in its circulation through the 

 capillaries, and the tortuosity and complica- 

 tion of the numberless small veins, account 

 for the regular and uninterrupted stream 

 which we meet with in the larger branches. 

 To prove that this is the explanation of the 

 fact, if you open a vein that has free and 

 direct communication with the extremity 

 of an artery (its capillary structure), the 

 blood wiU flow from it with the same pul- 

 satory motion as if the artery itself had 

 been penetrated : but if the vein be one of 

 large size, remotely situated from any arte- 

 rial communication, or if it be one that 

 springs from the union of numerous capil- 

 laries, that smooth and even stream, with 

 which the blood circulates in the trunks, 

 will be observable here. These facts, then, 

 lead us to conclude that the force of the 

 heart is not sufficient of itself to propel 

 blood through the venous system." 



From the collected accounts of writers 

 on this subject, it seems highly probable, 

 that the blood flowing in the veins receives 

 additional momentum from the reaction of 



