REN. 



245 



With the inconsiderable exceptions above 

 mentioned, the terminal twigs of the artery 

 correspond in number with the Malpighian 

 bodies. Arrived here, the twig, which is usually 

 of considerable length, although occasionally 

 very short, perforates the capsule, and, dilating 

 suddenly, breaks up into two, three, four, or 

 even eight branches, which diverge in all 

 directions like petals from the stalk of a 

 flower, and usually run in a more or less 

 tortuous manner, subdividing again once or 

 twice as they advance over the surface of the 

 ball they are about to form. (Fig. 153.) 



Fig. 153. 



1. Malpighian tuft. Horse. The injection has 

 penetrated only to the capillaries, a, the artery ; 

 f, one of its terminal twigs (or the afferent vessel 

 of the Malpighian body) ; d, the dilatation and mode 

 of breaking up of the terminal twig after entering 

 the capsule ; the division of the tuft into lobes, /, /, /, /, 

 is well seen ; i, i, intervals between the lobes. Mag- 

 nified about eighty diameters. 



2. Malpighian tuft. Horse. The injection has 

 penetrated through the tuft, and has filled the affer- 

 ent vessel, f, the afferent vessel ; d, its dilatation 

 and mode of division ; m, m, Malpighian capillaries ; 

 e, efferent vessel springing from them, and leaving 

 the capsule between two primary branches of the 

 afferent vessel. Magnified about eighty diameters. 



3. Malpighian body. Horse. The injection, after 

 filling the primary branches of the afferent vessel, 

 has burst into the capsule, and passed off along the 

 tube. It has not filled the tuft of capillaries, which 

 consequently are not seen, nor has it spread within 

 the capsule over the whole surface of the tuft, f, 

 the afferent vessel ; d, its dilatation and mode of 

 subdivision ; c, c, the outline of the distended capsule ; 

 t, the tube passing from it ; m, situation of the un- 

 injected Malpighian tuft. Magnified about seventy 

 diameters, -(After Bowman.) 



The vessels resulting from these subdivisions 

 are capillary in size, and consist of a simple, 

 homogeneous, and transparent membrane. 



They dip into its interior at different points, 

 and, after further twisting, reunite into a single 

 small vessel (fg. 154. ].), which varies in 

 its size, being generally smaller, but in some 

 situations larger, than the terminal twig of the 

 artery. This vessel emerges between two of 

 the primary divisions of the terminal twig of 

 the artery, perforating the capsule close to the 

 vessel, and, like it, adhering to the membrane 

 as it passes through. It then enters the 

 capillary plexus, which surrounds the tortuous 

 uriniferous tubes. (Fig. 154. 2. and 155.) The 



Fig. 154. 



1. Malpighian body, &c., from the horse. Mal- 

 pighian tuft, from near the base of one of the medul- 

 lary cones, injected without extravasation, and 

 showing the efferent vein branching like an artery, 

 as it runs into the medullary cone, a, arterial 

 branch ; e, the afferent vessel ; m, the Malpighian 

 tuft; f, the efferent vessel; b, its branches enter- 

 ing the medullary cone. Magnified about seventy 

 diameters. (After Bowman.) 



2. Malpighian bodies, &c., from the horse. The 

 injection has passed, as in Jig. 155., but without rup- 

 ture of the Malpighian tuft. a, branch of the 

 artery; f,f, afferent vessels; m, m, Malpighian 

 tufts ; e, e, efferent vessels ; p, plexus surround- 

 ing the tubes ; s t, straight tube in cortical substance ; 

 c t, convoluted tube in ditto. Magnified about thirty 

 diameters. 



tuft of vessels thus formed is a compact ball, 

 the several parts of which are held together 

 solely by their mutual interlacement, for there 

 is no other tissue admitted into the capsule 

 besides blood-vessels. It is subdivided into 

 as many lobes as there are primary branches 

 of the terminal twig or efferent vessel, and 

 these lobes do not communicate, except at the 



R 3 



