24 



shells above the mud and in the position where it Avill be pos- 

 sible for them to obtain the most food. On this account thosfr 

 individuals that are nearest to the surface of the reef in any 

 given generation will be the largest, Avhile those that are at- 

 tached nearest the mud, where they are perhaps covered with 

 sediment for the greater part of the time each day, will show the 

 result of their hardship in their smaller size and poorer condition. 



In places where the bottom is generally hard, and there is. 

 present some material to serve as a place of attachment for the 

 fry, it will be found that the oysters are not crowded together 

 in dense clusters, as they are over the soft bottom, and in this 

 case there will be a very noticeable ditference in the shape and 

 condition from that of those on the crowded reef. Instead of 

 being long, narrow and thin, they will be much more rounded 

 and deeper between the shells, so that the bodies of two oysters 

 of the same length of sTiell taken from the different reefs will 

 differ very much in volume. 



While the presence of a very soft bottom on any area has 

 a tendency to make the oysters growing there of poor quality, and 

 to restrict the amount of surface covered by the reefs, it fur- 

 nishes, on the other hand, the most favorable conditions for the 

 growth of the minute plants which make up the food supply 

 of the oyster. Since the restrictions imposed by the softness 

 of the bottom can be overcome by artificial means, a region 

 where the bottom is generally soft offers the best opportunity 

 for growing oysters successfully. The means of bringing about 

 the changes necessary for the preparation of a soft bottom to 

 receive seed oysters, or to start a plant by affording a place of 

 attachment for the spat, will be discussed under the head of, 

 cultural methods. 



FOOD. 



The food of the fry and young spat consists of bacteria 

 and some of the protozoans, the most minute organisms known. 



Dr. Ryder describes the food found in the stomachs of 

 newly attached spat as follows: 



*"Many of the food balls found in the stomach of the re- 

 cently attached spat will measure less than .001 of an inch 

 in diameter. The cavity of the little creature's stomach measures; 



* Hyder, .T. A.. Report T'. S Fish rommission. ISS.^. pp. 3S73SS. 



