(d) The digestive glands have also been shown to be excretory (5, p. 270).
It favors the excretory action of the skin, thus purifying it.
One of the prominent openings admits the food and the water required in respiration, the other is the excretory aperture.
The excretory organs of the Vertebrata consist of three distinct glandular bodies and of their ducts.
The development of the Elasmobranch excretory system has been mainly studied by Semper and myself.
The general features of the excretory organs at this period are diagrammatically represented in the woodcut (fig. 387).
For a considerable period the pronephros constitutes the sole functional part of the excretory system.
Further changes take place in connection with the excretory system on the conversion of the Ammocœte into the adult.
For a long time the pronephros and its duct form the only excretory organs of larval Amphibia.
There is still considerable doubt as to the mode of formation of the excretory tubes of the Chtopoda.