URIXIFEROUS TUBES AND MALPIGHIAN CORPUSCLES. 



931 



sometimes of only - tli or 77- th of an inch. They consist each of a mem- 

 branous capsule, containing a tuft of blood-vessels. The vascular tuft or 



Fig. 650. DIAGRAMMATIC RE- pjg^ Q%Q 



PRESENTATION OF A PART OP 

 THE STRAIGHT AND CONVO- 

 LUTED URINIFEROUS TUBFS 

 WITH THE GLOMERULT (from 

 Frey after a drawing by 

 Miiller). 



6, by two large straight tuhes 

 in the medullary substance of the 

 pyramid; c, convoluted tubes 

 with several of their termina- 

 tions in the Malpighian cap- 

 sules as iu d ; a, three arteries 

 passing up the pyramid and 

 dividing into branches to the 

 glomeruli : the efferent vessels 

 are also represented and the 

 network of capillaries between 

 them and the veins. 



glomerulus is formed by a 

 small afferent artery break- 

 ing up at once into a num- 

 ber of minute branches, 

 which possess simple nu- 

 cleated walls, form convo- 

 luted loops, and are re- 

 united in a single efferent 

 vessel, placed close to the 

 afferent : the further his- 

 tory of the afferent anl 

 efferent vessels will be de- 

 scribed later. The capsule, 

 by which the glomerulus is 

 surrounded, is formed of 

 homogeneous membrane. 

 The capsule receives the 

 two vessels at one part ; 

 and at another it is con- 

 tinued into a convoluted 

 uriniferous tubule, as was 

 first pointed out by Bow- 

 man. Gerlach and others 

 have considered that it 

 may be formed on one side ; 

 or may be so placed at the 

 extreme point of a looped 

 tubule, that it appears to 

 be continuous with two 

 tubuli ; but it is now gene- 

 rally admitted, as the result 



of filling the tubes both by injections from the ureter and by extravasation 

 from the glomeruli, that, although in certain amphibia they may be placed 



8P 2 



