592 SCIENTIFIC RECORD FOR 1882. 



ments and naturalists were on their side seeking what could be done 

 for the old world, and Messrs. Hoek and Horst in the Netherlands, and 

 Bouchon-Brandely in France, especially took up the investigation of the 

 question. These several naturalists have materially added to the infor- 

 mation previously gleaned by Davaine and Brooks, and the results of re- 

 cent investigations have been ably digested by Mr. Ryder in " a sum- 

 mary of recent progress in our knowledge of the culture, growth, and 

 anatomy of the oyster." From that summary we derive the following 

 data, using in most cases Mr. Ryder's own words: 



The oysters of greatest economical importance are three in number,'' 

 (1) the common species of Northern Europe, Ostrea edulis; (2) a more 

 southern species, formerly not occurring northward of the Lusitanian 

 peninsula, Ostrea angulata, and (3) the ordinary Virginia oyster, Ostrea 

 virginica. 



Accordingto M. Bouchon-Brandely, " twenty or twenty-five yearsago 

 the Portuguese oysters, indigenous to the Tagus, did not exist on the 

 coasts of France. A damaged vessel discharged its cargo into the 

 Giroude, upon the old Banc de Richard. Here they have since so mul- 

 tiplied that they cover an extent of from twenty-five to thirty kilome- 

 ters, a vast bed which will soon be limited only by the banks of the 

 river. 



Ostrea edulis is undoubtedly hermaphrodite - - - "The Portu- 

 guese oyster is, on the other hand, incontestably unisexual. Like the 

 American oyster, as shown by Brooks, its ova and milt are expelled 

 from the shell. Neither ova nor embryos are ever found in its mantle. 

 The young of the common oyster cannot live outside of the shell. Ac- 

 cording to M. Berthelot's investigatious the fluids in the mantle cavity 

 of 0. edulis contain albumen in a notable proportion, upon which the 

 young are supposed to be nourished. M. Bouchon-Brandely found that 

 the young of 0. edulis, whether in the form of white or gray spat, could 

 not be developed in sea water external to the parent; the white embryos 

 died in three days, the gray after twelve or fifteen days after their re- 

 moval from the parent, although within reach of collectors. These facts 

 he thinks, preclude the possibility of the crossing of the species. With 

 respect to this point, however, our author made direct experiments, or 

 attempts to hybridize the two species, which gave only negative results. 

 Mixtures of the eggs of 0. edulis with the milt of 0. angulata and rice 

 versa, never resulted in fertilization, although the experiments were 

 repeated at difiereut times for the last two years. 



M. Bouchon-Brandely succeeded in artificially fertilizing eggs of 0. 

 angulata. The vital properties of both elements were retained for two 

 to three hours. The embryos began to swim at Verdou in seven hours. 

 The shell was formed on the sixth to the seventh day. The temperature 

 of the water was 22 deg. C. (equal to about 71 deg. Fahr.). The artificial 

 fecundation j)resented no difficulties. Four times out of five, if good 



