[15] ARTIFICIAL PROPAGATION OF OYSTERS. 755 



Their influence seems to be a most disastrous one. They not only con- 

 sume the oxygen and such small quantities of food as may exist in the 

 water, but appearances indicated a direct attack upon the ciliated, em- 

 bryo oysters. We frequently observed numbers of embryos, that had 

 developed in a perfectly normal manner, lying at the bottom of the jars 

 and plates, incapable of movement on account of the absence of cilia, 

 and after continued observation of embryos and infusoria in watch 

 crystals, I feel a reasonable certainty that upon the first indication of 

 impaired vitality on the part of the oyster embryo, it is immediately at- 

 tacked by the infusoria. Of one thing there is no doubt whatever ; the 

 destruction of young and the advent of infusoria are coincident, though 

 which is the cause and which the effect is not so clear. Probably each 

 accelerates the other. 



Supply of food. — Considering the immense number of embryos col- 

 lected in a comparatively small receptacle, in these and similar experi- 

 ments, it is evident that the maintenance of anything like an adequate 

 supply of food is a very difiQcult matter. Indeed, it is not yet positively 

 ascertained what the food of the embryo is and until that point is set- 

 tled it is hardly possible to devise any method of supi)lying the aquaria. 

 The probability is that the bacteria evolved from the decomposing 

 matter in the waters of creeks, rivers, and littoral area, form the princiijai 

 article of food, but the difQculty of obtaining and affording a sufQcient 

 supply to the millions of embryos in a jar or plate seems insurmounta- 

 ble. Brooks tried to produce the bacteria by decomposing starch 

 and then adding the water to the aquaria, but met with no success, 

 and as little attended the use of ordinary ditch water diluted with that 

 from the sea. By collecting water and mud from an oyster bottom 

 lying remote from the dense waters of the Inlet, and adding small 

 quantities to the water already in the plates, we met with a moderate 

 degree of success; the young oyster, as seen under the microscope in a 

 watch crystal, attracting and securing minute particles of animal or 

 vegetable matter, and digesting them. In quite a number of cases the 

 stomach was gorged with food and the sweep of the cilia, continually 

 brought more within reach of the minute animals. Notwithstanding 

 this success, however, the embryo died eventually without making any 

 material advance, and I account for this destruction by the supposition 

 that we were unable to supply sufficient food, each oyster obtaining 

 but a small amount compared with its necessities and normal sup- 

 ply; and also by the fact that after a day or two the amount of sedi- 

 ment carried in with the water containing the food was sufficient to 

 smother the embryo. Those oysters under observation certainly did 

 thrive very well ; their shells were large and well defined, and though 

 we saw none that had actually attached to any '' cultch," yet Dr. Brooks 

 discovered numbers of shells, which had not been separated, with one 

 of the valves very much larger than the other. As it is well known 

 that immediately after attachment, the upper valve grows much more 



