Methods have been introduced for the purpose of breaking up the bodies of bacteria and setting free the intracellular toxins.
The ingestion of bacteria by the cells, and the subsequent intracellular digestion.
With regard to the nature of intracellular toxins, there is even greater difficulty in the investigation and still less is known.
Externally, the nephridium opens by a straight part of the tube, which is often very wide, and here the intracellular lumen becomes intercellular.
Nephridia generally paired, often very numerous in each segment, in the form of long, much-coiled tubes with intracellular lumen.
The nephridia in this group are invariably coiled tubes with an intracellular lumen and nearly invariably open into the coelom by a funnel.
This pigment is usually intracellular, but may be found lying free in the intercellular substance, and is generally in the form of fine granules of a yellowish-brown or brown-black colour.