The kidneys

however, have, as
has been said, a small cavity. From this cavity in the kidney there
lead two considerable ducts or ureters into the bladder; and others
spring from the aorta, strong and continuous. And to the middle of
each of the two kidneys is attached a hollow sinewy vein, stretching
right along the spine through the narrows; by and by these veins are
lost in either loin, and again become visible extending to the
flank. And these off-branchings of the veins terminate in the bladder.
For the bladder lies at the extremity, and is held in position by
the ducts stretching from the kidneys, along the stalk that extends to
the urethra; and pretty well all round it is fastened by fine sinewy
membranes, that resemble to some extent the thoracic diaphragm. The
bladder in man is, proportionately to his size, tolerably large.