. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 250 REN. ation of blood in the tuft than occurs pro- bably in any other part of the vascular system ; a delay that must be increased by the tor- tuosity of the channels to be traversed. The other system of capillaries, or that surrounding the uriniferous tubes, corre- sponds, in every important respect, with that investing the secreting canals of other glands. Its vessels anastomose with the utmost free- dom on every side, and lie on the deep sur- face of the membrane that furnishes the secretion. Mr. Bowman has applied
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 250 REN. ation of blood in the tuft than occurs pro- bably in any other part of the vascular system ; a delay that must be increased by the tor- tuosity of the channels to be traversed. The other system of capillaries, or that surrounding the uriniferous tubes, corre- sponds, in every important respect, with that investing the secreting canals of other glands. Its vessels anastomose with the utmost free- dom on every side, and lie on the deep sur- face of the membrane that furnishes the secretion. Mr. Bowman has applied the term "portal system of the kidney " to the series of vessels connecting these two, on account of the close analogy it seems to bear to the vena porta, intervening, like it, between two capillary net- works, the first of which answers to that in which the vena porta originates, and the second to that in which the vena porta ter- minates. The capillary plexus surrounding the tubes differs, therefore, from that of other glands, and agrees with that of the liver, in its receiving blood that has previously tra- versed another system of capillary vessels. The correctness of the analogy which Mr. Bowman has drawn between the circulation of the kidney and that of the liver is very beautifully shown by his observations on the kidney of the boa-constrictor, an animal which may be regarded as the type of those in which, besides the renal artery, the kidney receives a portal vein derived from the hinder part of the body.* Mr. Bowman thus de- scribes the organ in question : —" The kidney of the boa, being composed of isolated lobes of a compressed reniform shape, displays all the points of its structure in peculiar sim- plicity and beauty. At what may be termed the hilum of each lobe, the branches of the vena porta and duct separate from those of the renal artery and emulgent vein ; the two former spreading side by side, in a fan-like form, over the opposite surfaces o
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