BULLETIN OF THE UNITED STATES FISH COMMISSION. 383 



OX TBIIO MODE OF FIXATION OF THE FRY OF Til 10 OYSTER. 



By JOHN A. RYDER. 



During the past season five American investigators have been en- 

 gaged in the investigation of the question of the feasibility of rearing 

 Ostrea virginica from its eggs. Of these, Dr. Brooks, Lieut. Francis 

 Winslow, and Henry J. Eice, have not yet, as far as I am aware, pub- 

 lished anything upon what they have done. Col. Marshall McDonald 

 and the writer were engaged, during a part of the months of July and 

 August last, with the investigation, in the United States Fish Commis- 

 sion station at Saint Jerome's Creek, Maryland. The most remarkable 

 result which Colonel McDonald and myself obtained, with an apparatus 

 devised by the former, was the apparent fixation of the fry to the sides 

 of the glass hatching-vessels twenty-four hours after impregnation. 

 We found in a temperature of 73° to 80° Fahr., that they would develop 

 a larval shell in this short space of time, but were surprised to find 

 the young apparently fixed in such numbers to the sides of the glass 

 hatching- vessels. How they were attached we failed to learn ; whether 

 by means of a byssus or not could not certainly be determined. They 

 were found fixed so firmly, however, that they could be removed only 

 by force, such as scraping the clean, dead oyster shells upon which they 

 had lodged in the apparatus. Holding the shells upon which the fry 

 had caught under a strong stream of water from a faucet failed to dis- 

 lodge them. Our conclusion was, in view of the foregoing facts, that 

 these young embryos had voluntarily attached themselves. It was 

 noticed that this young fry had a disposition to lie upon the side, with 

 the border of the rudimentary mantle projecting over the border of the 

 shell. Many were noticed in other positions, but I am inclined to be- 

 lieve that these were not normal, as will appear further on. The pro- 

 jecting border of the mantle, as it appeared to the writer, is probably 

 the organ by which the adhesion of the embryo is effected — in fact, we 

 will learn further on that this flatwise position of the fry is assumed at 

 the time of fixation. Unfortunately for us, our endeavors to repeat 

 our first successful experiment, which had given us such a remarkable 

 result, invariably ended in failure, although we had taken the precau- 

 tion to vary again and again the character of the apparatus to meet 

 what were supposed to be unfavorable and fatal conditions. Several 

 other forms of apparatus were used, which worked so unsuccessfully 

 that their use was discontinued, including the air-blast playing upon 

 the surface of the water in the hatching-vessels, upon which I had 

 largely built my hopes last year. 



The fixed embryos or fry alluded to above did not grow any during 

 the three days which we were permitted to observe them, both in a 



