601 



BLACK FISH. 



BLADDER. 



.602 



tively assert that this bird was not, as suggested in a note (p. 343), a 

 hen pheasant with the feathers of a cock. Such birds are well known 

 to me, and it noways resembled them. To Mr. White's description of 

 the bird above, where he says that the back, wing-feathers, and tail 

 were somewhat like the upper parts of a hen partridge, I scratched 

 out at the time the words ' somewhat like,' and wrote in the margin 

 ' much browner than,' and with that correction I believe Mr. White's 

 description to be quite correct." 



Notwithstanding Mr. Herbert's opinion, Mr. Yarrell has stated his 

 conviction that the hybrid grouse of White's ' Natural History of 

 Selborne ' to be a young Black-Cock having nearly completed his first 

 moult. 



Of undoubted cases of hybrids arising from a mixture with the Gray 

 Hen, the following are related. 



At a meeting of the Zoological Society on the 24th of June, 1834, 

 Mr. Sabine called the attention of the meeting to a specimen of a 

 hybrid bird between the Common Pheasant (Phasianut Colchictu, 

 Linn.) and the Gray Hen (Tetrao telrh; Linn.), which was exhibited. 

 Its legs were partially feathered ; it bore on the shoulder a white 

 spot ; and its middle tail-feathers were lengthened. Mr. Sabine stated 

 his intention of entering at some length into the history of hybrid and 

 cross animals in connection with his description of this bird, which 

 was bred in Cornwall. This bird was a male. 



On the 12th of May, 1835, at a meeting of the same society was 

 read ' Some Account of a Hybrid Bird between the Cock Pheasant 

 (PhasianiM CoMdcu, Linn.) and Gray Ken .(Tetrao tett-ir, Linn.), by 

 Thomas C. Eyton, Esq.' This paper was illustrated by the exhi- 

 bition of the preserved skin of the bird, and also of a drawing made 

 from it. 



The subjoined table shows some comparative measurements between 

 the hybrid bird in question (the Cock Pheasant) and the Gray Hen : 



The late Mr. W. Thompson, of Belfast, has also described a hybrid 

 of this kind that was shot in Wigtonshire ( ' Mag. Zool. and Bot.' vol. i.). 

 Mr. Yarrell, in the second volume of his ' British Birds,' has also 

 recorded other instances. 



BLACK FISH. [CESTROLOPHCS.] 



BLACK JACK, the name given by miners to the Sulphuret of Zinc. 

 [Zl*C.] 



BLACK-THORN. [PRUSCS.] 



BLAIHiKK, or Veirica I'rinana, so called to distinguish it from the 

 Gall-Bladder, is a musculo-membranous bag or pouch, which serves as 

 a temporary reservoir for the urine ; it communicates with the kid- 

 neys by means of the ureters, and opens externally by means of the 

 urethra. 



The urinary apparatus is confined to the red-blooded classes of 

 animals, all of which have kidneys, whilst some orders and genera 

 have no urinary bladder. In quadrupeds the bladder is of a pyriform 

 shape, and is completely surrounded by the peritonaeum or serous 

 lining of the abdomen ; and it may be taken aa a general rule that it 

 is smaller, stronger, and more muscular in carnivorous than in grami- 

 nivorous animals ; in the latter it is almost membranous, and in some 

 of them is particularly large. 



In the whole class of birds there is no urinary bladder, and the 

 ureters open into the cloaca, a musculo-membmuous bag, which takes 

 the place of the rectum, bladder, and uterus, and serves as a reservoir 

 for the solid excrements, the urine, and eggs. The urine in these 

 animals dilutes the fcces, and deposits the carbonate of lime which 

 constitutes the basis of the shell. The urinary bladder exists in sevi 

 ral genera and species of fishes. 



In the human subject the urinary bladder is placed in the pelvis 

 or basin immediately behind the symphysis pubis, and before the 

 rectum, or terminal portion of the intestines, in the male; but 

 it is separated from it in the female by the uterus and vagina. 

 Its form and relations vary according to the age of the individual. 

 In infancy it is of a pyriform shape, and is contained almost 

 entirely in the abdomen, thus resembling its permanent condition in 

 (|na<lrupeds. At this period it may be considered as consisting ol 

 three portions ; the narrow tapering part, or neck, the upper rounded 

 portion, or fundus (sometimes called summit), and the intermediate 

 [K.rtion, or body; but as the pelvis expands the bladder gradually 

 Hiilxl.li * into it, and undergoes a remarkable change of form. Thus, 

 in the adult its figure is that of n short uval, compressed at the fore 

 and back part ; its lower surface subsides on the rectum, and expand 



ng forms what is termed by auatomists the baa fond of the bladder. 

 This change of form is dependent not only upon the enlargement of 

 ;he cavity in which the bladder is contained, but also upon the weight 

 af the fluid which it habitually sustains, and thus in advanced age it 

 3 more deeply sunk in the pelvis than in the middle periods of life. 

 n the female its transverse diameter is greater than in the male, iu 

 consequence of the antero-posterior diameter of the pelvis being 

 encroached upon by the uterus. Its capacity varies in the different 

 periods of life ; and as a general rule it may be said to increase in 

 proportion as the individual advances in years, and to be greater in 

 females than in males. Its capacity is modified in different individuals 

 jy their habits and the natural 

 ixercise of its functions. It is 

 more particularly changed by 

 disease ; thus, from the effects of 

 long-continued irritation it may be 

 reduced to such a state that it 

 will not contain more than a few 

 drops of urine ; and, on the con- 

 trary, when from any cause its 

 contents cannot be duly evacuated, 

 it may be distended so as to con- 

 tain many quarts of urine, and 

 occupy a large proportion of the 

 abdomen. Its ordinary capacity 

 may be estimated at a pint and a 

 half. 



The neck or constricted portion 

 of the bladder is compared to a 

 truncated cone, longer at the 

 sides and below than above. In 

 infancy, owing to the position of 

 the bladder, its direction is 

 oblique; for a similar reason it 



Fig. ]. The Ureters, running from 



the kidneys to the bladder, 

 a, Aorta ; b, bifurcation ; c, abdo- 

 minal muscles turned down ; 



rectum cut and tied ; , 



is horizontal in the adult; it ff< ureterg . g g> kidce} .;. 



rf, the 

 bladder ; 



differs in structure from the rest 

 of the organ. The neck, which Is formed of a somewhat fibrous 

 whitish substance, is the connecting medium between the bladder 

 and the urethra. Its posterior part rests on the rectum ; its anterior 

 is surrounded, at least below and at the sides, by the prostate gland, 

 which is peculiar to the male, and is composed of an aggregation 

 of mucous follicles, disposed so as to form three lobes, one on each 

 side of the neck of the bladder, and one below called the middle lobe, 

 which forms a slight projection into the opening of the urethra. 



The bladder, like the other hollow viscera, is composed of three 

 layers, or coats, united to each other by cellular tissue ; these coats are 

 the peritonaea! or serous, the muscular, and the mucous. The 

 peritonseal coat has been already described as investing only a portion 

 of the organ ; it is united to the muscular coat by cellular tissue, 

 which is extended over the whole of the latter, being however thinner 

 under the peritonseal coat than elsewhere. The muscular coat has 

 been described by some anatomists as a distinct muscle under the 

 name of detrusor uriua; ; it is composed of pale fibres interlacing in 

 all directions. Three distinct layers have been described, but it is 

 sufficient for all useful purposes to say, that the superficial fibres are 

 directed in the course of the axis of the bladder ; that at the sides 

 they are more and more oblique ; and that the more internal fibres 

 assume a circular direction as they approach the neck of the bladder, 

 so that some anatomists have described them in this part as a distinct 

 muscle, under the name of sphincter vesicse. This reticulated 

 structure of the muscular coat enables the bladder to contract so 

 perfectly as to expel every drop of its contents. 



When the bladder is much distended, the muscular coat becomes 

 attenuated to such a degree, that it is difficult to distinguish it from 

 cellular tissue. Sometimes its fibres become so much enlarged from 

 the effects of long-continued irritation and overaction of the organ, 

 that they form projecting lines or columns under the mucous coat ; 

 this appearance of the bladder is dessignated by the French Vessie h. 

 Colonnes. The mucous membrane is occasionally protruded between 

 these columns, forming sacs, or pouches, in which urinary calculi are 

 sometimes lodged; these calculi are then said to be encysted or 

 sacculated. The muscular coat is united to the third, last, or mucous 

 coat by a distinct layer of cellular tissue, to which the term nervous 

 or vascular coat is sometimes improperly applied. The mucous coat, 

 or lining of the bladder, belongs to that division of the mucous 

 membranes denominated genito-urinary ; it not only lines the bladder, 

 but is prolonged upwards along the ureters into the kidneys, and 

 downwards along the urethra ; it is of a pale rose-colour, is smooth 

 when the bladder is distended, and corrugated when it is empty ; it 

 secretes a viscid fluid termed mucus, which protects it from the 

 acrimony of the fluid with which it is constantly in contact. Three 

 openings are seen in it ; two situated posteriorly, about an inch and u 

 half from each other, which are the openings of the ureters, and one 

 anteriorly, which is the opening of the urethra. Extending from 

 the openings of the ureters to that of the urethra are observed two 

 prominent lines, which are formed by muscular fibres elevating the 

 mucous coat ; these lines form the sides of a triangle, the base of 

 which is an imaginary line drawn between the openings of the ureters 



