UROGENITAL SYSTEM 139 



The human urinary bladder occupies an intermediate place 

 and measures, according to its contents, 50 to 100 mm. in height, 

 40 to 80 mm. in breadth, and is capable of containing 200 to 

 400 cubic cm. The lobes of the human kidney being united 

 into a single whole, as is the case in most of the mammals, the 

 human organ has the same bean-like form and smooth surface 

 as that of the mammals, and only in rare cases is its construc- 

 tion of separate lobes revealed by an uneven surface. The 

 human kidney, however, on being compared with the kidney of 

 the mammals presents certain structural peculiarities, as, for 

 instance, the number of papillae. These, in man, are to the 

 Malpighian Pyramids always as 10 : 15, whereas the oran-utan, 

 rabbit, dog, cat, cavy, hyrax, lutia, Rhyzaena and gryson 

 possess but one papilla, and some rodents, Mus, for instance, 

 have two, while the elephant has three, the hedgehog five, 

 and the pig nine to eleven. Tereg l gives the following 

 diameters for the glomeruli of man and of various domestic 

 mammals : 



Man ..... O'2 mm. 



Horse . . . . 0*187 ., 



Cattle .... 0'22i 



Sheep .... O'2io 



Goat . . . . O'iSo ,. 



Pig 0-175 



Dog 0-136-170 



Cat O'i22 



As regards the convoluted tubules the difference is less 

 important. Their diameters are as follows : 



In man ..... O'O5 mm. 

 the horse .... 0^05 1 



cattle 0-05 



the sheep . . . o - o6 



goat . . 0-051 



,, pig 0-05 



dog 0-048 



The kidney of the Oran-utan has neither lobules nor Co- 

 lumnae Bertini ; further, no renal calyces are present, and only 



1 In Ellenberger, Vcrgl. Histol., p. 264. 



