KIDNEY. 



[ 450 ] 



K1RKBYA. 



differences, which relate principally to the 

 following particulars : 1, the form, which 

 in birds, fishes, and reptiles is considerably 

 more elongated, and frequently flattened ; 

 2, the tabulation, which in the human adult 

 kidney is indistinct, although marked in 

 the foetus, whilst in that of other Vertebrate 

 the separate lobules are very distinct, some- 

 times being connected only by the branches 

 of the ureter ; 3, the Malpighian tufts, which 

 in birds, reptiles, and fishes consist of a 

 single convoluted vessel, and which in some 

 (naked reptiles) are larger, in others (osseous 

 fishes) smaller than in man, whilst in birds 

 (also the sheep) they have been found 

 inserted into the sides of the tubules ; and 

 4, in the structure and arrangement of the 

 urinary tubules : these are uniform in size 

 in fishes, furnished with ciliated epithelium 

 in the reptiles and fishes, Ttnd present varie- 

 ties in regard to the convolution, branching, 

 and termination in the ureter. 



Renal organs have been noticed in the 

 Mollusca, Arachnida, and Insecta. 



The epithelial cells of the urinary tubules 

 are not unfrequently found to contain the 

 ordinary urinary deposits, which are more 

 often still met with in the cavities of the 

 tubules. Many of these are probably, how- 

 ever, formed after death (see URINARY 

 DEPOSITS). 



Among the morbid changes of the kidney, 

 passing over cancer, tubercle, variations in 

 the degree of vascularity, the presence of 

 calculi" and the ordinary products of inflam- 

 mation, may be mentioned the occurrence 

 of cysts. 'These are met with of various 

 size and in variable number. The walls 

 of the cysts do not differ in structure from 

 those of'the tubules, except in being thick- 

 ened; they have been accounted for as 

 arising from dilatation of the tubules or 

 Malpighian capsules, in consequence of 

 obstruction to the escape of the urine, 

 distention of the epithelial cells of the 

 tubules, and degeneration of their nuclei, 

 forming colloid cells. The first is probably 

 the general cause, and certainly an occa- 

 sional one, the Malpighian tufts having 

 been found within the enlarged cysts after 

 injection. Sometimes the cysts are those of 

 jEchinococci. In Bright's kidney the tubules 

 are found deprived of their epithelium, 

 the cells filled with albuminous, fibrinous, 

 or fatty matter, and the fibrous tissue 

 increased, in the advanced stage both 

 becoming un distinguishable in some parts, 

 whilst in others the cells and tubules are 



loaded with fatty globules, producing the 

 well-known granular appearance. And in 

 certain cases, the kidneys become "waxy," 

 the Malpighian corpuscles and intertubular 

 spaces, sometimes the tubules also, being 

 filled with amylaceous corpuscles. 



In examining the structure of the kidney, 

 sections must be made with a Valentin's 

 knife. The arrangement of the vessels may 

 be shown by injection; and the injected 

 preparations are very beautiful, and form 

 general favourites. The Malpighian bodies 

 are readily filled, the injection being thrown 

 into the artery ; and they are easily recog- 

 nized by their resemblance to little apples 

 upon the branches of a tree (PI. 39. fig. 35). 

 The injection should be red. If the injec- 

 tion be coarse, it will burst through the 

 capillaries of the tufts, and partly till the 

 tubules as in fig. 383 p ; but if it be fine, 

 it will fill the venous plexus. The urinary 

 tubules should be injected from the ureter, 

 white (lead) injection being used; and con- 

 siderable force' is required to make a good 

 injection, but this must be very gradually ap- 

 plied. Frey recommends the cold ferridcya- 

 nide injection, or carmine with glycerine or 

 gum. The tubules can be well examined by 

 boiling pieces of the kidney with very dilute 

 sulphuric acid, or in alcohol mixed with 

 muriatic acid ; or by digestion in cold con- 

 centrated muriatic acid, the pieces being 

 subsequently macerated in water, to remove 

 the acid. 



The kidneys of the smaller and lower 

 animals are best injected from the heart. 

 The' usual staining processes are very useful. 



BIBL. Kolliker, Mik. An. ii. ; Bowman, 

 Phil. Tr. 1842; Johnson, TodcTa Cyclop. 

 art. Een\ Toynbee, Med. Chi. Tr. xxx. ; 

 Forster, Path. Anat. ; Frerichs, Brightsche 

 Nierenkrank. ; Gairdner, Edinb. M. Jn. 

 viii. ; Todd and Bowman, Phys. Anat. ; 

 Henle, Abh. Gesells. Wist. Gottin. x. ; 

 Ludwig, . Strieker* 8 Handb. i. 489 ; Rind- 

 fleisch, Path. 18/8, 434; Gross, Structure 

 Mic. du Rein, Strasbourg, 1868; Frey, 

 Mikr. 1881, and Histol 1876, 554. 



KIRK'BYA, Jones. A small bivalved 

 Entomostracan, of the Leperditiadas family, 

 and nearly allied to Beyrichia. The valves 

 ridged longitudinally and concentrically, 

 often reticulated superficially, and impressed 

 with a subcentral pit. Fossil in the Palaso- 

 zoic rocks, from the Silurian to the Permian, 

 and often very abundant. 



BIBL. R.Jones, Tr.TynesideNat. Club'iv. 

 134; Ann. N. H. ser. 4, iii. 223. 



