460 SCHULTE, SEI WHALE. 



ficial position, the other extremely delicate investing the individual renculi and sending septa 

 between them into the interior of the organ. These are both recognized and described by Daudt, 

 who terms the ectal one the capsula fibrosa, the ental tunica albuginea. In addition to these 

 delicate septa, coarser ones are present surrounding groups of lobules, and in these both layers 

 of the tunica fibrosa appear to participate. I have not however verified this point histologically. 

 Of these latter by far the largest and strongest is on the ventral surface extending from the 

 point of entry of the renal artery to the emergence of the ureter. There thus is in addition to 

 the renculus, a larger architectural unit composed of groups of renculi, defined by coarser con- 

 nective tissue septa, and this type of organization appears to be an additional difference between 

 the kidney of the mystacete and that of the odontocete with its smaller number of renculi. These 

 groups are irregular in shape and variable in the number of renculi they contain. There is a 

 tendency on the ventral and dorsal surfaces to the rectangular form with longitudinal and trans- 

 verse septa; laterally the arrangement becomes wholly irregular. The number of renculi in 

 a group varies between seven and thirty, but a large majority of the groups are composed of nine 

 to fifteen. In size the individual renculi varied between 1 and 1.5 mm. A rough count of the 

 number in the left kidney, the smaller of the two yielded 1350. This is far below the count 

 of Beauregard and Boulart, 3000, and Daudt states his own counts to have been but little less. 

 In this connection the process of increase becomes important. Nearly half of the renculi in 

 this kidney show signs of subdivision, into two, three or even four parts. A count of 100 showed 

 60 to be simple, 30 divided by a sulcus into two parts, 6 into three, and 4 into four. If all these 

 subdivisions were actually accomplished, the count would be still a third less than that of 

 Beauregard and Boulard. 



The right kidney has a length of 35 mm. Its greatest breadth and thickness coincide with 

 the level of its penetration by the blood vessels; the former dimension is 18.5 mm., the latter 

 9.5 mm. Caudad of the vessels the organ diminishes in breadth to the rounded caudal pole, 

 the margins being straight; the mesal is blunt, but the lateral is expanded to a surface well 

 defined from the dorsal and ventral faces. It is well shown in Daudt's l schematic cross-section. 

 Rostral to the vessels the ventral surface is beveled off so that it looks rostrad and laterad as 

 well as ventrad; here it is in contact with the liver. In the region of the vessels and separated 

 from the hepatic surface by a sagittal prominence a small area is directed mesad, ventrad and 

 slightly rostrad, which is in contact with the duodenum and coils of the small intestine. The 

 borders of the kidney rostrad converge almost to a point, which is inserted between the liver 

 and the adrenal. 



The left kidney is appreciably smaller than the right, measuring 32 mm. in length, 14 mm. 

 in breadth and 9 mm. in thickness. It is distinctly more slender, its margins more nearly par- 

 allel, and it lacks the marked broadening at the level of the vessels. In consequence the lateral 

 margin lacks the angle present on the right at this point. The rostral pole is broadly convex 

 and not pointed. The lateral surface is well demarcated from the flat dorsum, but passes into 

 the ventral surface by a gradual curve. 



The dorsal surfaces of both kidneys are nearly flat resting against the hypaxial muscles. 

 Their lateral surfaces are in apposition with loose areolar tissue, which fills the angular space 

 between them and the transversalis, but as yet no fat has been deposited here. The ventral 



1 Op. tit., text fig. 4, p. 274. 



