Carbonate of lime often occurs in the urine, in the form of an amorphous powder, when it deposits phosphates; it is produced by the decomposition of phosphate of lime by carbonate of ammonia, derived from the urea.

Calculi are concrete masses, made up of one or more of the various substances we have mentioned, the several particles of which, if crystalline, are held together by mutual attraction; if amorphous, are united

together by some animal matter. Thus Dr. Walshe states the case, and no doubt correctly; but we have recently examined a small calculus, which consisted of octohedra of oxalate of lime, united together by a

considerable quantity of mucus, in which they were imbedded. The following description of the several varieties of calculi is an abbreviation of Dr. Prout's: (1) The lithic acid calculus is generally of a brownishred, or fawn color, sometimes approaching that of mahogany. Its outer surface is commonly smooth, the sectional displays numerous concentric laminæ. Its shape is generally ovoid; its size very various; it is the commonest species; dissolves completely in liquor potassæ, and in nitric acid with heat, the dry residuum presenting a beautiful pink color. (2) Lithate of ammonia calculus is of a clay color, composed of concentric layers; its outer surface smooth, or slightly tuberculated; its sectional

marked by concentric layers. It chiefly occurs in children under puberty, and hence is generally small, and rather rare. It behaves in several respects like the preceding, but is more soluble in water, and gives off ammonia when heated with caustic potash. (3) The oxalate of lime calculus is generally of a dark-brown color, from adhering and Fig. 295.

Fig. 296.

altered blood, but may be pure white. Its surface is rough and tuberculated (mulberry), its texture is hard and laminated. When heated it is decomposed, the acid being destroyed, and an alkaline ash (lime) remaining. Heated in a tube with sulphuric acid, carbonic acid and carbonic oxide gases are given off, and may be recognized by the former being absorbed by liquor potassæ, and the latter burning with a blue flame. (4) The cystic oxide calculus is of a yellowish-white; its surface is smooth, and of a crystalline aspect. It is not laminated, but appears

to be made up of a multitude of irregularly aggregated crystals, and has internally "the color and shining look of beeswax." It is soluble both in acid and alkalies, and crystallizes in hexagonal tablets from its ammoniacal solution. (5) The phosphate of lime calculus is of a pale-brown color, and smooth porcelaneous surface. It is regularly laminated, and the laminæ are vertically striated. It is not common, and does not Fig. 297.

Fig. 298.

attain a large size; is soluble in hydrochloric acid, and precipitated from its solution by liquor ammonia as a white powder. (6) Phosphate of ammonia and magnesia calculus is nearly white, its surface is uneven; it is friable, and not laminated, except in some rare instances, when it

is hard, crystalline, and more or less transparent and laminated. It yields ammonia when heated, fuses with difficulty, is soluble in dilute hydrochloric acid, and is precipitated from this solution by ammonia as prisms or stellæ. (7) The fusible calculus, a mixture of the two preceding, is whiter and more friable than any other, often of very large size, and occurs frequently. It melts readily, is soluble in dilute hydrochloric acid, and its ammoniacal precipitate consists of amorphous particles

and stellar crystals. (8) The alternating calculus is made up of two or more layers of different urinary deposits, as seen in the following examples; a nucleus of uric acid may exist with a covering of urates, oxalate of lime, or phosphates-the nucleus may be oxalate of lime with a covering of uric acid, urates, or phosphates; a nucleus of uric acid may be covered by oxalate of lime, and this by mixed phosphates, or the latter may be replaced by uric acid; again, a nucleus of oxalate of lime may be covered by uric acid, oxalate of lime, and phosphate of lime in succession. More than half the whole number of calculi are alternating, and it is especially to be observed, that, in a very great proportion of instances, the outer crust consists of phosphates; so that Dr. Prout has stated it as a law, that a decided deposition of the mixed phosphates is not followed by any other. (9) The carbonate of lime calculus is very uncommon; it is perfectly white, and very friable. We think it is occasionally found as a coating to renal calculi, being thrown out from the irritated mucous membrane. In one such case it appeared under the microscope as grains and round globules, about the size of those of the blood; it effervesces strongly with acid, and the lime after neutralization with ammonia can be precipitated by oxalate of ammonia. (10) Uric or xanthic oxide calculi are very rare; they are of a light-brown color externally, "and of a brownish flesh-color in their interior;" their surface is smooth and polished; they consist of concentric layers, and assume a waxy lustre on being rubbed. For its chemical characters we refer to Mr. Coulson's work, p. 282. (11) The fibrinous calculus is of small size, of amber color, and waxy consistence, and is probably only indurated fibrin, or mucus, therefore not a true urinary concretion.

CHAPTER XXXVI.

ABNORMAL CONDITIONS OF THE MALE GENERATIVE

ORGANS.

Testicles and vasa deferentia.--There is no sufficient evidence to show that more than two testicles ever exist. They are absent when the entire sexual apparatus is wanting, and in some rare cases they are imperfectly formed, or one only may exist. An apparent absence of one or both glands at birth is not very unfrequent, the descent of the organ being arrested or delayed, so that it lies in the groin, the inguinal canal, or the lower part of the abdomen. Of one hundred and three male infants examined by Wrisberg at the time of birth, seventy-three had both testicles in the scrotum; while in twenty-one, one or both were in the groin, and the remainder had one or both in the abdomen. He found the imperfection more frequently on the left than on the right side, in the proportion of seven to six. Mr. Curling believes that if the descent does not take place within twelve months after birth, it is seldom fully and perfectly completed afterwards without being accompanied by hernia. The reason of this is sufficiently apparent, the pressure of the muscular walls of the abdomen must tend to cause the descent of the intestine through the open inguinal canal. When the testicle is still in the abdomen at birth, it may descend, and usually does, within a few weeks (it did so in ten out of the twelve cases mentioned by Wrisberg), or it may not descend till some time before puberty, or it may not appear at all. The cause of the testis remaining in the abdomen is considered by Mr. Curling, with much probability, to be owing either to paralysis and defective development of the cremaster muscle, or to the contraction of adhesions between the gland and some adjacent viscus. The discovery of the continuation of muscular fibres from the fixed attachment of the cremaster up along the gubernaculum to the testis in its primitive situation by the side of the vertebral column, inclines us strongly to believe that these fibres must be the agents in causing the descent of the gland into its appointed place. Contraction of the external abdominal ring is also mentioned as one of the causes impeding the descent of the testis. In rare instances, the testis wanders into other situations; one has been found in the perineum, the other being normally placed; and in two instances a testicle has preferred to make its exit by the crural instead of the inguinal canal. Sometimes it happens that the gland is turned round in the scrotum, so that its anterior face becomes posterior. It is quite ascertained that the abnormal situation of the testes in the abdomen is by no means inconsistent with the full discharge of their