Democratic Sentinel, Volume 9, Number 25, Rensselaer, Jasper County, 17 July 1885 — Architecture of the Oyster. [ARTICLE]

Architecture of the Oyster.

At a meeting of the American Association for the Advancement of Science a paper was read asserting that the extreme age of an oyster is twenty years. Now I have previously demonstrated that an oyster might be in fair edible condition at the age of thirty years. Here are the shells of one of the oysters on the characters of which the statement was based. This double shell is thirty years old, and the inclosed mollusk was large and in fair condition. In building its shell the oyster starts with the hinge end, at the spot known to conchologists as the umbo. A small plate or single scale now represents each valve, and that is the first season’s growth. The next season a new growth or plate shoots out from underneath tne first one, just as the shingles do. The oystermen call these laps, or plates, “shoots, ” and they claim that the number of shoots indicates the years of the oyster. They certainly do contain a record of the seasons, showing the slowgrowing and fast-growing seasons. But there is often great difficulty in clearly differentiating these shoots. The record is often obliterated in places by the growth of parasites, which build their shells or tubes upon the oyster. I have likened these shoots to shingles. Now, at the gable of a house these shingles may be seen edgetvise. So on the one side of an oyster shell is a series of lines. .This is the edgewise view of the shoots or season growths. Another factor is this purple spot, or scar, in the interior of the shell. It is the place of attachment of the abductor muscle. Its first place of attachment was close up to the hinge. Had it stqud there until the shell had become adult, how difficult would be the task of pulling the valves together! the leverage to be overcome would be so great; for we must bear in mind the fact that at the hinge end the valves are held by this black ligament, which is, in life, elastic, swelling Avhen the shell opens and being compressed when the animal draws the valves together. So with every year’s growth or elongation of the shell the mollusk moves the place of attachment of the muscle onward; that is, an advance further from the hinge. As it does so it covers up with white nacre all the scars that are back of the one in actual use at the point of attachment of the muscle. This you can prove by eating off Avith nitric acid this covering, and thus exposing the whole life series of scars or attachments.— Prof. Lockwood.