UREDO. 
of any other excrement, becomes a rich source of 
the nitrogenous element in the nutrition of 
plants. See the articles Urine, Liquip Ma- 
NURE, Guano, and AMMONIA. 
UREDO. A large genus of minute hypoder- 
mous fungi, of the eutophytous group, and co- 
niomycetous tribe. Several species are identified 
with two of the worst corn diseases of our country; 
about 60 species produce on various plants of the 
gardens and wilds of Britain the diseases which 
are popularly called blight and rust and mildew; 
and many species occur in other countries, ad- 
ditional to those which occur in Britain. See 
the articles Minpew, Smut, and Funevs. Most 
of the species in Britain have either a brown, 
orange, or yellow colour; and the greater number 
appear and come to maturity in summer or the 
early part of autumn. Species of a pulverulent 
or finely powdery nature infest the leaves of fica- 
ria, potentilla, bramble, and carex ; species of a 
scattered nature infest the leaves of geranium, 
primrose, alchemilla, beet, armeria, hypericums, 
epilobiums, anthyllis, burnet, and various um- 
belliferee ; species of a spreading nature infest 
the leaves of polygonum, alchemilla, and various 
rosace; species which grow in a spotted man- 
ner infest the leaves of sorrel, and various com- 
posite and scrophulariacez ; species which grow 
in the manner of patches infest the leaves of 
sphondylium and the bean-plant; species which 
have the appearance of pustules infest the leaves 
of mint, luzula, and sallow; species which have a 
mottled appearance infest the leaves of sallow 
and rose; species which have a gyrose appear- 
ance infest the leaves of coltsfoot, mercury, and 
raspberry; species which have a bright or bril- 
liant appearance infest the leaves of saxifrage, 
campanula, and purging flax; species which 
have a very minute appearance infest the leaves 
of dock, polygonum, vaccinium, oak, and equise- 
tum; and species which have a different appear- 
ance from any of the preceding infest the leaves 
of common field thistle, willow, ragweed, rye, 
stinking iris, bellflower, periwinkle, cerastium, 
and various leguminose. 
URENA. A genus of exotic plants, of the 
mallow family. Upwards of a dozen species,— 
some of them annuals, and others small ever- 
green shrubs,—some with leaves undivided or 
slightly three-lobed, and others with leaves deep- 
ly and sublobedly three-lobed or deeply and 
sublobedly five-lobed,—and most about 2 or 3 
feet high, and carrying either red or purple or 
carmine-coloured flowers,—have been introduced 
to British gardens, principally from India and 
tropical America. The most interesting is the 
showy, U. speciosa, an evergreen shrub of about 
3 feet high, carrying pink flowers in November, 
introduced in 1828 from Ava, loving a soil of 
sandy loam, and requiring to be propagated from 
cuttings. 
URETERS. The ducts which convey the urine 
from the kidneys to the bladder. Those of the 
URINE. 547 
ox are considerably larger than those of the 
horse, and have a stronger internal membrane, 
and terminate nearer to the neck of the bladder 
and nearer to each other. 
URETHRA. The membranous and muscular 
canal which conveys the urine from the bladder. 
In the male horse, it is of considerable length, 
but, though making a curvature in passing over 
the bones of the pubis, is seldom if ever obstruct- 
ed; in the ox, it is at once long and narrow and 
curved, and is frequently obstructed by calculi; 
and in mares and cows, it is very wide and short, 
and easily admits of an artificial withdrawal of 
retained urine by means of introducing the fin- 
ger and keeping the neck of the bladder open. 
See the articles Catcunus and Lirnoromy. 
URIC ACID. See Urnatus. 
URINARY CALCULI. See Carcutus. 
URINE. The excrementitious liquid which 
is separated by the kidneys and collected in the 
bladder and expelled through the urethra of 
animals. It does not serve any ulterior purpose 
in the animal economy; but it is entirely an 
excrement, and simply consists of substances 
which are not wanted in the system, and whose 
accumulation or retention would disturb the 
health or endanger or destroy the life. It there- 
fore is exceedingly compound; and contains va- 
rious saline principles, animal earths, and highly 
azotised peculiar principles; and is necessarily 
avery powerful fertilizer. It widely varies in 
composition in different species of animals, in 
different states of health, under different kinds 
of regimen, and according to the kind and quan- 
tity of liquid received into the stomach; and 
it widely varies, also, in comparative quantity 
within any given period, and in the comparative 
degree of its concentration or dilution. A normal 
or very healthy specimen of it from the human 
subject is transparent, limpid, and of an amber 
colour; and has a saline taste, and a specific 
gravity of about 1:03; and, while warm, emits 
a slightly aromatic and not disagreeable odour; 
and gives a red tint to litmus paper, evincing 
the presence of a free acid or of a super-salt ; 
and, after standing a few hours, makes a percep- 
tible deposit of insoluble matter, and throws up 
ascum or light floating cloud of mucus and of 
super-urate of ammonia. Most other urine, ex- 
cept such as is either very morbid or excessively 
diluted, possesses similar chemical characters, 
and has a thicker consistency than water, and 
ranges in specific gravity at from 1:005 to 1:033 ; 
and all urine, no matter how healthy, soon be- 
gins to putrefy on exposure to the atmosphere, 
becomes turbid and dark-coloured, emits first an 
urinous odour and afterwards an alkaline and 
very offensive fetor, loses its acid reaction, de- 
posits the earthy phosphates, and gradually 
generates a large quantity of carbonate of am- 
monia; and it undergoes similar changes by 
continuous boiling, and owes them in either case 
principally to the decomposition of its urea. See 
