[3] EXPERIMENTS IN OYSTER CULTURE RYDER. 765 



ture of water ranged to-day from 87° to 78° Fahr. The apparatus for 

 blowing air upon the surface of the water in the glass hatching-dishes 

 was applied to-day; it seemed to help to keep the water aerated and 

 cooler by 3 or 4 degrees than in a vessel over which the air was not 

 blown. Added a little, not over a tablespoonful, of a saturated calcic 

 hydrate solution [lime-water] to the water in which the embryos were 

 developing at 3.30 p. m. This was probably soon after converted into 

 calcic carbonate by combination with the free carbonic dioxide in solu- 

 tion in the water. 



I fertilized a fine series of eggs to-day at 12 m. and 12.20 p. m., which 

 were developing finely at 3.30 p. m. Added a little lime-water or calcic 

 hydrate to the water in which these last were developing, as soon as 

 they were placed in the hatching-house. 



In order to test the possibility of changing the water on the eggs, I 

 devised a simple filtering apparatus, constructed as follows : Over one 

 end of a straight-glass argand lamp-chimney I secured a diaphragm of 

 filtering paper between single thicknesses of light muslin or cheese- 

 cloth, the whole held to the chimney by a stout rubber band, which 

 bound down the free overlapping edges of the cloth and paper to the 

 chimney all around. This apparatus was found to answer to a certain 

 extent, but, like all the filters hitherto tried, was found to clog up and 

 finally become impervious. The chimneys were suspended with a pe- 

 culiarly arranged wire ring, which it is unnecessary to describe, depend- 

 ing for about two-thirds of their length into shallow glass bottles with 

 wide necks. The fresh water was poured into the upper open ends of 

 the chimneys from time to time by hand, and allowed to percolate 

 through the diaphragm below into the bottle, overflow from the latter 

 around the chimneys, and run off. This arrangement would work for 

 a while only ; the diaphragm would finally clog altogether, and, if the 

 number of embryos in one of the chimneys or cylinders was too great, 

 l^utrescence was soon established, when our experiments would come to 

 an end. It was also found that the chimneys were too deep ; their great 

 depth, as compared with their width, would force the eggs to settle on 

 the small area on the diaphragm at the bottom, tending to suffocate the 

 ova, arrest their development, and kill them. In order to change the 

 water, I then resorted to common glass funnels and filtering i)aper, with 

 indifferent success. 



I to-day examined some of the oysters one year and eleven months 

 old, which had caught on the collectors put into the creek in August 

 and September, 1880, by my party, under the auspices of the Maryland 

 Commissioner. The largest specimen measured 3f inches in length and 

 2§ inches in width. Another smaller specimen was found to measure 

 2 inches in width and 2^ inches and a quarter in length. These speci- 

 mens were found to have the reproductive organs developed and con- 

 tained ripe spawn. This showed how rapidly oysters which were started 

 from the egg would develop in the course of twenty-three months. 



