BULLETIN OF THE UNITED STATES FISH COMMISSION. 17 



Vol. IT, ]\o. 2. Washington, D. C. April 9, 188i. 



9.— 0:V A KEW FORm OF FII.TFB OR DIAPDRA0.7I TO BE USFD IIV 

 THE €UL,TLRE OF OVSiTERS IN PONDS. 



By JOHN A. RVDER. 



The unexpected success which crowned, in a measure, the attempt 

 made by the writer, in association with Mr. H. H. Pierce and Mr. G. V. 

 Shepard, at Stockton, Worcester County, Maryland, during the past 

 summer, to rear the spat of the American oyster from artificially fertilized: 

 eggs in an inclosed iiond connected with the open water by a trench 

 only, into which a permeable diaphragm was fitted to give ingress and 

 egress to the ebbing and flowing tides from without, in order to change 

 the water in the pond, has given us experiences which will enable us 

 to greatly improve the diaphragms to be used in the connecting trenches, 

 and also render it possible to clean or renew the filter of sand when- 

 ever desirable or necessary ; also to increase or diminish at icill the thich- 

 ness of the stratum of sand used as the filter and as a harrier to prevent 

 the escape of the emhryo oysters sicimmhig about in the ])ond. Such a 

 diaphragm the writer proposes to describe and figure in this communi- 

 cation, believing that for simplicity and effectiveness the apparatus in 

 its present form cannot fail to be in a large measure the means of ob- 

 taining spat at will and also the means of preventing the escape of the 

 swimming embryos of oysters cultivated in j^onds or coves with narrow 

 outlets. 



The fertility of the oyster, as shown by the investigations of scientific 

 men, is truly astounding ; some conception of this fact may be gained 

 when it is stated that a single female oyster, according to its size, may 

 I>roduce all the way from one to one hundred millions of eggs in a sin- 

 gle season. How to save, in a measure, this vast yield of germs from 

 wholesale destruction, has engaged the practical attention, for several 

 years past, of such men as Professors Brooks, Rice, Lieutenant Winslow, 

 U. S. T^., and Col. M. McDonald. In Europe, with the Portuguese oyster, 

 the greatest success in artificial culture has been attained by Bouchon- 

 Brandely, of Paris. The viviparous Ostrea edulis of Europe has also 

 been thoroughly studied by Messrs. Hoek, Hubrecht, and Horst, of Hol- 

 land, Avith prospects of ultimate success in its artificial propagation. 

 Science has therefore been more thoroughly awakened to the impor- 

 tance of studying the life-history of these three, probably the most 

 valuable of all edible mollusks, during the last half decade than ever 

 before, and it is not too much to say, that more real knowledge of eco- 

 nomical value has been gained, respecting especially the American oys- 

 ter, during this brief renascence than had been acquired during the 

 Bull. U. S. F. C, 84- 2 



