These are protoplasmic manufactures destined for some useful purpose, but they do not long exist in their original form; being often broken up into other compounds, they are reabsorbed, or pass away with the faeces. These bodies are found in the various secretions. Most of them can be better described with the function of the gland which forms the secretion in which they occur.

Attention must here be drawn to certain complex bodies existing in the bile. Some complex nitrogenous substances and the monatomic alcohol, cholesterin, will now also be mentioned. But the reader must remember that chemically they are not connected with the other bodies, the description of which immediately follows theirs, namely, the effete products.