200 EXPLANATION OF THE PLATES. 



PLATE XX. 



TUBULAR GLANDS, Continued. KIDNEYS. 



FIG. I. Portion of the kidney of a cat magnified 50 

 diameters. 1, Straight tubes of the medullary substance; 2, 

 tortuous tubes of the cortical substance ; 3, Malpighian tufts. 



'FiG. II. 1 and 2, Fresh tubes showing their internal epithe- 

 lial lining ; 3, a tube, throughout the greater portion of which 

 (4) its external wall only is visible contracted and slightly 

 wrinkled ; 5, detached epithelial cells ; 6, transverse section of 

 an urinary tubule ; 7, its epithelium ; 8, its cavity. 



FIG. III. Portion of an injected kidney (from Dr. 

 Boeckel), magnified 60 diameters. 1, Arteries; 2, Malpighian 

 tufts ; 3, afferent vessel ; 4, efferent vessel ; 5, vascular plexus 

 of the cortical substance; 6, same, of the medullary substance. 



FIG. IV. Diagrammatic representation of the structure 

 of the kidney. 1, A straight tube of the medullary sub- 

 stance ; 2, tortuous tube of the cortical substance ; 3, its ter- 

 mination in a bulbous expansion ; 4, an artery ; 5, Malpighian 

 tuft; 6, the efferent vessel; 7, capillary plexus; 8, veins in 

 which the vascular plexus pours its blood ; 9, relation between 

 the vascular portion of the Malpighian tuft, and the terminal 

 bulbous expansion of a tube; 10, epithelium covering the sur- 

 face of the Malpighian tuft, and lining the interior of the uri- 

 nary tube by the terminal bulb of which it is enveloped. 



PLATE XXI. 



^ ; ; /;; f.rj j>byH&7.ifft 9t<>ill iii.UU ft tfiv'Jfj. ,* \\*''--' 



TUBULAR GLANDS, Continued. OVAEY. 



FIG. I. Section of a testicle rendered hard by boiling, 

 magnified 50 diameters. 1, External wall of a secreting tubule ; 

 2, its internal tunic ; 3, its cavity and epithelium. 



FIG. II. A fresh tubule of the testicle. 1, Outer coat of 

 its wall ; 2, inner coat ; 3, polygonal epithelium. 



