THE URINARY ORGANS. 



603 



fitly termed arterice interlobulares (Fig. 245 a). It is these twigs which 

 support the Malpighian bodies, and, with the exception of some branches 

 to the coats of the organ, they terminate exclusively in the formation of 

 their vascular coils. In fact, each interlobular artery gives off, in its 

 whole length, on two, three, or four sides, a great number of fine twigs 

 possessing the structure of arteries and 0-008-0-02 of a line in diameter, 



Fig. 248. Fig. 249. 



which, after running a short distance, either directly or after dividing 

 once, penetrate the tunic of the Malpighian body, becoming the vasa 

 afferentia of its vascular coil. Each of these (Fig. 247, 248) consists 

 of a close convolution of fine vessels 0-004-0-008 of a line in diameter, 

 having the usual structure of capillaries (structureless coat and nuclei) 

 and possesses, besides the afferent artery, an efferent vessel, the vas 

 efferens. The mode in which these two vessels are connected is not 

 that which usually obtains in arteries and veins, but corresponds with 



Fia. 248. From the Human kidney, after Bowman: a, extremity of an interlobnlar 

 artery; b, afferent arteries; c, naked glomerulus ; d, efferent vessel; e, glomeruli, surrounded 

 by the Malpighian capsules; /, tubuli urinifcri springing from them. Magnified 45 

 diameters. 



FiQ. 249. Glomerulus from the innermost part of the cortex of the kidney of the Horse, 

 after Bowman: a, arter. interlobularis ; a/, vas afferens ; m w, glomerulus; ef, vas efferens s. 

 arteriola recta; b, divisions of the same in the medullary substance. Magnified 70 diameters. 



