420 



DISCOVERY REPORTS 



stage the centres of the lobes still present the appearance of a tangled mass of capsules, 

 with their tubules and collecting ducts (Figs. 23, 27, 30). Thus, along the inner and 

 outer circumference of the crescent of kidney substance in very young stages, the 



Fig. 24. Transverse section of the whole kidney of a Fin whale foetus o-6 m. in length, (x 5.) 

 The section shows five or six lobes. Note that they are small and less distinct in the region of the mesal 

 slit (c). The lobes are sub-divided into well-defined lobules, which are themselves beginning to divide 

 into renculi. 



a. Interlobar septa. 



b. Interlobular septa. 



c. Mesal slit. 



d. Central connective tissue core. 



e. Urinary duct. 



/. Outer layer of fibrous investment (serosa). 

 g. Inner layer of fibrous investment (capsula 

 fibrosa). 



lobulation of the primary lobes can be distinguished, but is as yet undiscernible within 

 the body of the crescent. 



In rather older stages (kidneys from foetuses about 0-5 m. in length) the lobulation is 

 distinct throughout and each lobe of kidney substance is seen to be divided into an 

 irregular number of discrete lobules, almost separated from one another by the inter- 



