892 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [2] 



assume the form of tb.e grown oyster, aud become of a black color. 

 Either owing to the lack of water, or because they need no movement 

 for their further development, they remain quiescent in the shell until 

 they are ejected by the mother oyster, and then they adhere to various 

 objects, such as wood, mud, stones, &c. 



Leeuwenhoek^ (1G95) seems to have known and observed the eggs of 

 the oyster independently of Brach. From a letter dated the 18th day 

 of the calends of September, we learn that an oyster opened on August 

 4th was found filled with an enormous number of young oysters, which 

 moved about rapidly in the water by means of the small organs which 

 projected from their shells and which they drew in when they died 

 {velum aiict.). They resembled the grown oyster as much as one Ggg 

 resembles the other, but they were so small that, according to Leeuwen- 

 hoek's calculation, it would take 1,728,000 to make a ball one inch iu 

 diameter. Leeuweuhoek seems also to have observed younger stages of 

 development; at least in a later letter (dated the 15th day of the calends, 

 of September) he states that he found in some oysters a number of 

 small unborn young, which were much less developed than those which 

 he had previously observed, and which he could not be sure were alive. 



Two years later he wrote to the Royal Society of London ^ that one 

 day, when eating oysters at the house of a relative at Eotterdam, he 

 found one which was partly filled with a gray mucus. As he was in 

 doubt whether this mucus contained oyster eggs, he took some home 

 and examined it under a microscope, when he found that his supposi- 

 tion was correct, as this apparent mucus was entirely composed of young 

 oysters. 



Baster* (1759) added but li:tle to the above observations. He does 

 not agree with Leeuwenhoek and others who say that the sexes are 

 separated among the oysters. He thinks that the oyster is a genuine 

 hermaphrodite, because it cannot move about at will and consequently 

 cannot approach the female for the purpose of impregnation. 



Home^ (1826) saj's but little of the spawn of the oyster, and what he 

 says is not very accurate, much less so, in fact, than the statements of 

 j)ersous who had preceded him, and whom he does not even quote in 

 his work. He says that about the end of June the eggs issue from the 

 ovaries, and that towards the end of July none are found either iu the 

 ovaries or in the oviducts ; that the moment the egg leaves the oviduct 

 a kind of purplish mucus is secreted, which probably serves as nour- 

 ishment to the oyster during its stay in the cavity of the mantle. Once 

 in that cavity, the eggs often fall a prey to little aquatic worms which 

 slip into the shell. His paper is accompanied by several fignres of the 

 brood of the oyster. 



■^A. vau Leeu^veuhoek : Arcana Xaiura: Opera, T. II, Epist. 92 and 94. 



•' PMloBopliical Trausactions, vol. six, 1698, p. 798. 



•»Job Raster: XaiuurlcVitspanningen, 1759, p. 73. 



" On t he mode of breeding iu the oyster. Phios. Transact., 1827, p. 39, Plates II and IV. 



