408 



OF SECRETION. 



the whole gland a'lobulated character ; but in the Human Kidney they 

 come into closer contact ; and the vascular connexion between the 



Fig. 126. 



Fig. 125. 



Portion of Kidney from Coluber:~a, a, vascular trunk 

 b, b, ureter; c, c, converging fasciculi of tubuli uriniferi. 



Pyramidal fasciculi of tubuli uri- 

 niferi of Bird, terminating in one 

 of the branches of the ureter. 



plexuses of the different bundles is such, as to prevent any separation 

 into distinct lobules. 



728. The act of secretion appears to be effected, as in other Glands, 

 by the epithelial cells lining the tubuli uriniferi ; these cells drawing the 

 materials of their development from the vascular plexus upon the 

 exterior of these tubuli ; and delivering them up, when they have com- 

 pleted their own term of existence, to be carried off through the open 



Fig. 127. 



A section of the Kidney, surmounted by the supra-re- 

 nal capsule; the swellings upon the surface mark the 

 original constitution of the organ, as made up of dis- 

 tinct lobes. 1. The supra-renal capsule. 2. The vas- 

 cular portion of the kidney. 3, 3. Its tubular portion, 

 consisting of cones. 4, 4. Two of the papillae project- 

 ing into their corresponding calices. 5, 5. 5. The 

 three infundibula; the middle 5 is situated in the 

 mouth of a calyx. 6. The pelvis. 7. The ureter. 



Portion of the Kidney of a new- 

 born infant: A, natural size; 1, 1, 

 Corpora Malpighiana, as dispersed 

 points in the cortical substance; 2, 

 papilla ; B, a smaller part magnified ; 

 1, 1, Corpora Malpighiana; 2, 2, tu- 

 buli uriniferi. 



orifices of the tubuli. But the Kidney contains another apparatus, of 

 a very peculiar description ; which appears specially destined for the 



