KIDNEY. 



[ 450 ] 



KIEKBYA. 



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 lobulation, which in the human adult 

 kidney is indistinct, although marked in 

 tlie foetus, whilst in that of other Vertebrata 

 the separate lobules are very distinct, some- 

 times being connected only by the branches 

 of the ureter ; 3, the Malpighiau 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) thej'- 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, and pi'eseut 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 unfi'equenlly found to contain the 

 ordinary urinary -deposits, which are more 

 often still met with in the cavities of the 

 tubides. Many of these are probably, how- 

 ever, formed after death (see Ueinaey 

 deposits). 



Among the morbid changes of the Idduey, 

 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 wdth 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 Malpighiau tufls having 

 been found within the enlarged cysts after 

 injection. Sometimes the cysts are those of 

 JEchinucocci. In Blight's kidney the tubules 

 are found de^u'ived of tlicir epithelium, 

 the cells filled with albuminous, fibrinous, 

 or fatty matter, and the fibrous tissue 

 increased, — in the advanced stage both 

 becomiug undistinguishable in some parts, 

 whilst in others the cells and tubules are 



loaded with fatty globules, producing the 

 well-knowai granular appearance. And in 

 certain cases, the kidneys become "waxy," 

 the Malpighian corpuscles and intertubnlar 

 spaces, sometimes the tubules also, being 

 filled with amjdaceous 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 tlie 

 capillaries of the tufts, and partly fill the 

 tubides as in fig. 383 ^j; but if it be fine, 

 it will fill the venous plexus. The urinaiy 

 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 mu«t 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 be;)t injected from the heart. 

 The usual staining pi'ocesses are very useful. 



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

 Phil. Tr. 1842; Johnson, Todd's Cyclop. 

 art. JRtn\ Toynbee,' J/(?rZ. Clii. Tr. xxx. ; 

 Forster, Tath. Anat. ; Frerichs, Brightsche 

 Nierenkranh. ; , Gairdner, Edinb. M. Jn. 

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

 Henle, Ahh. Geselh. Wiss. 'OoUin. x. ; 

 Ludwig, Strieker's Ilandh. i. 489; Riud- 

 tieisch. Path. 1878, 434; Gross, Structure 

 Mic. du Rein, Strasbourg, 1868 ; Frev, 

 Mikr. 1881, and Tlistol. 1876, 554. 



KIRK'BYA, Jones. — A small bivalved 

 Entomostracau, of the I^eperditiada? family, 

 and nearly allied to Beijrichia. The valves 

 ridged longitudinally and concentrically, 

 often reticulated superficially, and impressed 

 with a subcentrnl pit. Fossil in tln^ Palaeo- 

 zoic rocks, from the Silurian to the Permian, 

 and often very abundant. 



BiiiL. R. Jones, Tr.Ti/nesideNat. Club,iv. 

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



