CHAP. VIII 



THE EXCRETION OF URINE 



419 



vessels, and relation to the Malpighian corpuscles, which he took 

 to be simple vascular tufts, distinct from the dilatations of the 

 ducts. Bowman (1842) first recognised the fundamental fact 

 that the vascular glomeruli are enclosed in the spherical dilatations 

 which he designated capsules in other words, that the Malpighian 

 corpuscles are terminal expansions of the uriniferous tubules, 

 embracing a vascular glomerulus (Fig. 108). 



The Malpighian corpuscles and their relation to the afferent 

 and efferent blood-vessels are plainly seen on injecting the vessels, 



FIG. 108. (Left.) Diagram showing relation of uriniferous tubules to blood-vessels. (After Bow- 

 man.) a, one of the interlobular arteries ; a', afferent artery passing into glomerulus ; e, 

 capsule of glomerulus ; t, convoluted tube ; e'e', efferent vessels which subdivide in plexus j,, 

 surrounding the tube, and finally terminate in interlobular vein, e. 



PIG. 109. (Right.) Plan of longitudinal section through pelvis and substance of right kidney. 

 One-half the natural size, a, cortical substance ; b, b, broad part of two pyramids of Malpighi ; 

 c, c, the divisions of the_pelvis named calices of infundibula, laid open ; <', one of these unopened : 



/, <l, summit of pyramids or papillae projecting into calices ; e, e, section of narrow part of'tu.i 

 pyramids near the callers ; /. pelvis or enlarged portion of ureter within thf kidney ; 11, ureter ; 

 s, sinus ; h, hilum. 



while non-injected preparations show the connection of the 

 capsules with the ducts. All subsequent work has merely 

 extended and completed the discovery of Bowman, who confirmed 

 the physiological concept formed by Malpighi from the corpuscles, 

 and so long contested by Ruysch and his adherents. Bowman, 

 however, made one fundamental modification in Malpighi's theory, 

 inasmuch as he held that the renal corpuscles excreted water. 

 and the uriniferous tubules the characteristic constituents of 

 urine. Malpighi and Johannes Miiller were the precursors, 

 Bowman was the creator, of the physiological theory of renal 

 secretion. 



We must briefly consider the structure of the kidney. It is 

 surrounded by a fibrous coat known as the capsule, which can 



