Dialysis blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus. The two main types of dialysis, hemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite.
Water organ contest between Apollo and Marsyas' and 'Apollo and the nine Muses'. The most famous water organ of the 16th century was at the Villa d'Este in Tivoli. Built about 1569–72 by Lucha Clericho (Luc de Clerc; completed by Claude Venard), it stood about six metres high under an arch, and was fed by a magnificent waterfall; it was described by Mario Cartaro in 1575 as playing 'madrigals and many other things'. G. M. Zappi (Annalie memorie de Tivoli, 1576) wrote: 'When somebody gives the order to play, at first one hears trumpets which play a while and then there is