46 bulletin of the united states fish commission. 



§ 4 (Extract from a letter from Mr. Pierce to Mr. Ryder, 



WITH comments by THE LATTER.) 



Snow Hill, Worcester County, Maryland, 



October 10, 1883. 



My Dear Mr. Ryder: * * * Before writiug yoa I wanted to 

 again visit the claire and the oyster beds, which I did yesterday. I was 

 not able to discover that the "brood" (spat) in the claire had increased 

 either in size or numbers. We placed some of the shells in the open 

 bay and then took away the diaphragm, so that now the claire is open 

 to tlie bay. It seems to me probable that the great amount of sediment 

 [deposited] upon the shells [in the course of the experiment] prevented 

 a large part of the catch which we ought to have had from fixing itself 

 to the collectors. Perhaps you can suggest next season some way by 

 which that difficulty can be overcome. 



I found yesterday some very small oysters on the shells in the claire, 

 and in the open bay; on the shells put out into the latter in June there 

 is every indication that the catch there extends from soon after the shells 

 were put out up to within a very few days. Some of the young oysters 

 [taken from the bay, this season's spat] measured about 2 inches long, 

 some were so small as to be not easily seen by the eye, except upon very 

 close examination, * * * 

 Most sincerely, yonrs, 



H. H. PIERCE. 



P. S. — It may be interesting to you to know that yesterday Mr. Shep- 

 ard, in opening some oysters out in the bay, found one with spawn 

 enough in it to plainly show, in fact he took the spawn from it. 



From Mr. Pierce's question as to the cessation of the growth of the 

 spat in the claire, I am reminded that apparently but little growth of 

 the shell, either of the adult or young oyster, occurs after cool weather 

 sets in. There is, in fact, a marked cessation of growth about the 

 end of October, as is shown by specimens of young oysters twenty- 

 three months old now before me. In one specimen of that age the 

 spat had grown during the first season to be 1| inches in diameter, 

 after which there is a sharp offset where the growth had ceased in the 

 autumn. This was the growth accomplished in about four months; 

 during the next succeeding nineteen months a growth of only 2 inches 

 had been made, so that the total length of the shell was now 3f inches 

 measured from the beak to the free edges of the valves. In other 

 specimens measuring 2^ inches, but of the same age as the preceding, 

 there is a similar sharp offset where the layers of calcic carbonate form- 

 ing the spat shell cease, and where the first year's growth suffered tem- 

 porary cessation. 



The fact that the young oyster should stop growing appreciably dur- 

 ing the autumn and winter is therefore not surprising, and this fact 



