Kidney always so simple; in cartilaginous fish and some amphibians, there is also a shorter duct, similar to the amniote ureter, which drains the posterior (metanephric) parts of the kidney, and joins with the archinephric duct at the bladder or cloaca. Indeed, in many cartilaginous fish, the anterior portion of the kidney may degenerate or cease to function altogether in the adult. In the most primitive vertebrates, the hagfish and lampreys, the kidney is unusually simple: it consists of a row of nephrons, each emptying directly into the archinephric duct. Invertebrates may possess excretory organs that are sometimes referred to as
Bladder pipe only distinction being the form and size of the air-chamber, either the bladder or the wind-cap, in which the reed was set in vibration. The player blows air into the bladder through the insufflation tube, or through the raised, slit-shaped opening of the wind cap, placed against the player's lips. This earlier Italian form of bladder pipe is found illustrated at the end of the 15th century in the Book of Hours, known as the "Sforza Book". An allusion to the bladder pipe occurs in an old English ballad: This excerpt suggests the early English bladder pipe retained a distinct