Certainly not all cases of renal dropsy show diminution in the excretion of chlorides.
During excretion they irritate the kidneys and the sweat-glands, and thereby increase the excretion of urine and of sweat.
This, like the excretion of the sundew and other insectivorous plants, contains a digestive ferment (or enzyme) which renders the nitrogenous substances of the body of the insect soluble, and capable of absorption by the leaf.
Stomata are often absent, absorption and excretion of gases in solution being carried on through the epidermal layer.
In the case of many Oligochaeta where there is no vascular network surrounding the nephridium, this function must be the chief one of those glands, the more elaborate process of excretion taking place in the case of nephridia surrounded by a rich plexus of blood capillaries.