OBSEEVATIONS OF GAILLON AND JOHNSTON, 737 



coast of New Jersey, in New York Bay, and Long Island Sound. I have ^een specimens from a 

 number of these localities, and also tasted them both raw and cooked without being able to detect 

 any disagreeable or apparently harmful flavor. 



Diatoms and green algse occur in great abundance in the stomach of the Oyster, especially the 

 former. The intestine is sometimes packed with countless numbers of the empty frpstules or tests 

 of diatoms, mixed with dark, muddy ooze or sediment and very fine particles of sand or quartz. 

 It has been objected that the green color could not be derived from diatoms, because these organ- 

 isms are, as a rule, apparently brown rather than green. This objection I find to bo based upon 

 a misapprehension of the structure of the Biatomacew, as may be gathered from the following 

 general statement taken from Sachs' "Text Book of Botany," one of the latest and highest 

 authorities. On page 222 he says: "The diatoms are the only algae except the Oonjugatce in which 

 the chlorophyl occurs in the form of disks and bands, but in some forms it is also found in grains, 

 and the green coloring matter, is concealed, like the chlorophyl grains in Fucacece, by a buff-colored 

 substance, diatomine or phycoxanthine." , It appears, then, according to the foregoing quotation, 

 that it is not impossible for diatoms to be the cause of the green tint in Oysters, which, let me 

 remark, is very nearly that of some pale green forms of those organisms which I have observed in 

 water from oyster coves where I have conducted microscopic studies. Both green and brown 

 diatoms may frequently be found iu the stomach, and in making examinations to discover them I 

 find it best to thrust the nozzle of a pipette directly into the stomach through the mouth and 

 oesophagus. The pipette should , have a compressiblie bulb, so as to enable one to draw up the 

 contents of the gastric cavity into the tube without injuring the animal or taking up any fragments 

 of it to vitiate the experiment. 



Observations of Gaillon and Johnston. — Speaking of the abundance of the Navicula 

 ostrearia of KUtzing, M. Benjamin Gaillon, in 1820, said that they inhabit the water of the 

 tanks or "parks" in which the Oysters are grown in such immense abundance, at certam seasons 

 of the year, that they can lonly be compared to the grains of dust which rise in clouds and 

 obscure the air in dusty weather. Dr. Johnston, speaking of the French Oysters, says that in 

 order to communicate to them a green color, which, as with us (in England), enhances their 

 value in the market and in the estimation of the epicure, they are placed for a time in tanks 

 or "parks," formed in particular places near high-water mark, and into which the sea can be 

 admitted at pleasure by fneans of sluices; the water being kept shallow and left at rest is 

 favorable to the growth of the green Gonfervce and Ulvce; and with these there are generated 

 at the same time innumerable crustaceous animalcules which serve the Oysters' for food and 

 tincture their flesh with the desirable hue. 



This last remark of Dr. Johnston's at first struck me as improbable, but I have met with great 

 numbers of small crustaceans,' Gopepoda mainly, in the branchial cavity of the common Clam {Mya 

 arenaria). Certain peculiar species have also been described by A,llman from the branchial 

 cavities of ascidians. Moi-e recently, while investigating the contents of the stomach of the 

 Oyster, by the method already described^ I find that it also swallows crustaceans, which, are digested 

 and absorbed as food. The tests of nauplii or very minute larval crustaceans with the contents 

 digested out were frequently met with. Doubtless many very small Copepoda are also swallowed 

 and digested, but these are not green. Besides the foregoing, I sometimes met with the very young 

 shells of larval gasteropods and lamellibranchs; indeed, it is not improbable that the adult Oyster 

 may consume its own larvse. The remains of bryozoa were also observed, such as Pedicellina 

 americana. The test of a peculiar elongate rhizopod and the eephalula stage of several worms 

 were also noticed. Of the smaller organisms usually associated with more or less clearly marked 

 47 P 



