The systems that excrete wastes from the body. For example, the system of organs that regulates the amount of water in the body and filters and eliminates from the blood the wastes produced by metabolism. The principal organs of the excretory system are the kidneys, ureters, urethra, and urinary bladder.
The latest stage of the excretory system which we have studied is in a young Fish of about 11 centims.
Hatschek (No. 514) has given a very interesting account of the development of the excretory system in Polygordius.
For a considerable period the pronephros constitutes the sole functional part of the excretory system.
The development of the Elasmobranch excretory system has been mainly studied by Semper and myself.
The excretory system has more work to perform and reaches a rather higher development.
Further changes take place in connection with the excretory system on the conversion of the Ammocœte into the adult.
In the same way the living machine has its excretory system for removing wastes.
Thus a cause is seen for excreting fluids by motor action of bowels, when supplied by the excretory system.
Who says heat is not a union of the human gases with oxygen and other substances as they pass out of the excretory system.
In the general account of the development we have already called attention to the earliest stages of the excretory system.