In common with the other monotremes, the male echidna has its heel provided with a sharp hollow spur, connected with a secreting gland, and with muscles capable of pressing the secretion from the gland into the spur.
Pure calcareous sand and calcareous mud are formed by wave action on the shores of coral islands where the only material available is coral and the accompanying calcareous algae, crustacea, molluscs and other organisms secreting carbonate of lime.
The male ducts often have glandular walls, secreting capsules or spermatophores within which the spermatozoa are packed for transference to the female.
We do not know at present if any corresponding anti-toxin or antitrypsin, as we may term it, is returned into the lymphatics or blood from the gland, but the pancreas, which in addition to secreting trypsin secretes a diastatic ferment forming sugar from starch, pours this into the intestine and secretes at the same time a glycolytic ferment which breaks up sugar, and this latter passes into the blood by way of the lymphatics.
Nemertines live in the sea, some being common amongst the corals and algae, others hiding in the muddy or sandy bottom, and secreting gelatinous tubes which ensheath the body along its whole length.
This condition is not so frequently seen in the more highly differentiated cells, but may follow necrosis of secreting cells, as is found in the kidney, in corrosive sublimate poisoning and in chronic nephritis.
At the apex of the rhopalium the endoderm is greatly thickened and consists of concrementcells secreting otoliths (Con).
The cells concerned, like all secreting organs, have abundant protoplasm with large nuclei, and sometimes, in addition, part of the cell-wall is modified as a filter.
Cockroaches are nocturnal creatures, secreting themselves in chinks and crevices about houses, issuing from their retreats when the lights are extinguished, and moving about with extraordinary rapidity in search of food.
I say I see the criminal, in my mind's eye, creeping stealthily into the room of our Ozma and secreting herself, when no one was looking, until the Princess had gone away and the door was closed.