October 5, 18S3.] 



SCIENCE. 



4G:$ 



tains over any other in tliis country, j'ct in 

 this artic4e lie has tried to put aside any per- 

 sonal bias, and he desires to carry conviction 

 •onl}- in so far as he has l)een able to adduce 

 facts, and to interpret them rationally and logi- 

 ■cally. He would state, further, that, if the 

 reader should take exception to anj- interpre- 

 tation given to the facts, the tables still stand 

 as the best and most reliable data of these 

 facts attainable, and they arc not to be con- 

 troverted. Saml. Aut;. FisK, M.D. 



Denver, Col. 



REARING OYSTERS FROM ARTIFICIAL- 

 LY FERTILIZED EGGS AT STOCK- 

 TON, MD. 



In order to test the feasibility of such an un- 

 dertaking on a considerable scale, a pond three 

 and a half feet deep was excavated on the prem- 

 ises of Messrs. George V. Shepard and II. II. 

 Pierce, not far from Stockton, near the shore 

 ■of Chincoteague Bay, and connected with the 

 latter by a trench ten-feet long, two feet wide, 

 and three and a half feet deep. Before the 

 water was let into the trench connecting the 

 pond with the bay, a wooden diaphragm — 

 made in the form of a box three feet deep, and 

 two and a half feet wide, and two inches tliiclc, 

 and lined on the inside with gunny-cloth ; the 

 sides of the box being perforated with numer- 

 ■ous auger-holes, and filled with clean sharp 

 sand, so as to form a filter — was placed in the 

 trench vertically and transverselj', and so se- 

 cured that no water, except such as had first 

 filtered through the diaphragm, could gain ac- 

 cess to the pond. In this way the natural fry 

 from the baj- was effectually excluded from our 

 artificial enclosure from the ver}; start, so that 

 the results of our experiment might not be 

 vitiated. In the construction of this simple 

 apparatus we depended entirely upon the rise 

 and fall of the tide to partially renew the water 

 in the pond in the intervals between the tides. 

 The tidal rise and fall of the water in the en- 

 closure was from four to six inches, or from six 

 to eight inches less than the rise and fall of the 

 tide iu the open ba}-. Into the enclosure, cov- 

 ering about fift}" square yards, artificially' fertil- 

 ized spawn was poured at odd dates, from Julj' 

 7 to the first w^eek of August. 



The spawii was taken from the adults much 

 in the same way as from fishes ; the right valve 

 of the adult animals being removed, and the 

 ducts of the reproductive organs stroked with 

 a pipette to force out the eggs and milt from 

 the females and males. The products mixed 

 together in water were then allowed to stand 



in pails for a few hours, until the eggs had de- 

 velo|)ed as far as tlie swimming stage. The 

 spawn so i)repared was then distributed over 

 different parts of the pond, and left to take care 

 of itself. 



The collectors used were simplj- oyster-shells 

 strung upon galvanized wire ; strings of shells 

 being suspended to stakes driven into the bot- 

 tom of the pond at intervals corresponding to 

 the dates when fresh lots of spawn were intro- 

 duced, each stake being marked with the date 

 when it was put in place. The suspended 

 oyster-shells were introduced so as to afford 

 the 3'oung fr^' clean surfaces to which it could 

 attach itself. On the 22d of August Mr. 

 Pierce found that some of the shells hanging 

 to the stakes had spat attached, ranging from 

 one-fourth to three-fourths of an inch in di- 

 ameter, and which had undoul)tedly been de- 

 rived from some of the brood placed in the 

 pond b^- us. Some specimens of these young 

 oysters are now in my possession, attached to 

 the perforated oyster-shells used as collectors. 



To our great surprise, we found that the 

 water in the pond maintained about the same 

 specific gravitj- as that in the bav, or 1.0175 to 

 1.018, and that the temperature of the water 

 was also the same as iu the open bay. The 

 microscopic vegetable food upon which the 03-s- 

 ter feeds was found to multiply rapidly in the 

 enclosure, inasmuch as it was confined by the 

 gate or diaphragm, so that it could not escape. 

 The water in the pond was also found to remain 

 sweet, and free from putrefactive odors. It 

 will accordiugl3- be seen, that all the conditions 

 of success had been established, as was fully 

 proved by the result. 



While it is too soon to affirm that artificial 

 breeding may be profitabl\- available on an 

 extensive scale in practical ojstcr-culture, our 

 experiment has demonstrated a number of very 

 important facts. These are : 1 . 03'ster-spat 

 may be reared from artificially fertilized eggs ; 

 2. The spat will grow just as fast in such 

 enclosures as in the open water ; 3. Food is 

 rapidly generated in such enclosures ; 4. The 

 densit3' of the water in the ponds is not m.ate- 

 riall3' affected b3- rains, or leaciiing from the 

 banks ; ."). Ponds are readily excavated in salt- 

 marsh lands, and can in all probabili,t3- be used 

 for fattening and growing Ostrca virginica for 

 market just as successfull3- as Ostrea edulis 

 and angulata are grown b3- a similar method 

 on the coasts of France. Pond-culture, where 

 there are salt-marshes adjoining arms of the 

 sea the waters of which have a densitv below 

 1.020, can doubtless be carried on profitably 

 in connection with the intelligent use of simple, 



