The water works.

A wet, wet day; just the day for a spot more microscopy.
This is a photograph of a small part of a very thin slice of kidney, stained to show the structure.
The large round structure at the centre is a glomerulus, a complex of blood capillaries sitting in a space in a thin walled sac (stained blue) known as a Bowman's capsule. This where the blood is filtered, the first stage in the production of urine. The other structures are sections through the Convoluted Tubules which are responsible for adjusting the composition and concentration of the urine.
Bowman's capsules are  named after the English surgeon Sir William Bowman, 1st Baronet, who identified it in 1842.