1 



44 



had formed previous to the "spatting," as it would prevent the exposure of the " cultch." The 

 sponge is of very rapid growth, and I was informed that ou an unworked bed it had been known 

 to become three or four feet thick in a few months. If, then, it had formed and commenced grow- 

 ing after the "spatting" season, the young would not be as much disturbed by it as they would 

 if the growth had heen previous to their advent. This is another reason in favor of the theory 

 that the depth of the water influences the time of spawning, as the effect of the sponge on the 

 numbers of young was greater in deep than in shallow water. 



The number of drills (astyris) was, generally speaking, in direct proportion to the number of 

 young, and the Poeomoke beds, especially the Bird and Hern Island Beds, appeared to have suf- 

 fered most from their ravages. A description and sketch of this animal, taken from specimens 

 preserved by me, has been made by Mr. W. H. Dall, Assistant Coast and Geodetic Survey, who 

 has kindly furnished me with copies. Very few star fish and welks and no other enemies were 

 discovered in the Sounds, and the drills are probably the only ones that do any considerable damage. 



With regard to the beneficial effect, or the reverse, of fresh water, there can be no doubt that 

 the oysters at least appear fatter and are superior after absorbiug it, though they become poorer 

 in flavor. In order to test the effect of fresh water upon them and to determine if the low spring 

 tides had any share in causing the decrease iu the numbers on the beds, a dozen oysters were 

 selected from the same bed and haul of the dredge. Six of them were opeued immediately and 

 inspected and found to be rather poor, of small size and dark color, but of the ordinary flavor. 

 The remaining six oysters w ere placed in perfectly fresh water for twenty four hours, the water 

 being changed several times during that interval. They were then opened and inspected. They 

 were alive and in good order, very fat, or apparently so, and of a creamy white color and much 

 swollen, but of very insipid taste. As the oysters were alive at the end of a day's immersion in fresh 

 water, they cannot well be destroyed by the brackish water of low spring ebbs, to which they 

 would not be exposed for more than six hours, though a continuance of heavy freshets might very 

 seriously affect them. As there is but one river in both Sounds (the Poeomoke) likely to subject 

 the oysters to this evil, for the main beds there is nothing to fear. 



The evil effects of sudden jars and concussions are probably due to the breakage of the delicate 

 pedal muscle, which after the spawning season, in common with all other parts of the animal, is in 

 a more or less weakened condition. 



In explaining the fact that the oysters iu deep water are more affected by cold water and ice 

 than those on the shoals, it is necessary to remember that the lower the temperature of sea water 

 the greater its density, ami thus as the surface water becomes cooler it would sink. The freezing 

 point of salt water is below that of fresh. Therefore the oysters in the deep water, or, generally 

 speaking, those remote from the mouths of the streams, may have surrounding them water of a 

 slightly lower temperature, depending upon the amount of salinity, than those oysters near the 

 creeks and rivers that are surrounded by ice. Again, the deep water would be much slower to 

 lose or acquire heat than that on the surface or in less depths, which would necessarily be affected 

 quickly by all changes of weather. 



The statement that the oysters recover and reappear after the "sanding" process, must be 

 received with great caution, opposed as it is to most experience. That some few may survive is 

 possibly the case, but that the majority recover after being covered with sand for any length of 

 time is very doubtful. 



The testimony of all persons in the neighborhood of the Sounds was to the effect that the beds 

 were deteriorating. In the absence of any reliable observations, extending over any length of time, 

 their opinions must be taken as correct, at least as to the fact, although perhaps only approximately 

 so as to the degree. Accepting, then, the statement, it is necessary to account for the deteriora- 

 tion if possible. 



After the original formation and growth of the beds they would at some time, the same con- 

 ditions continuing, cease their development, neither increasing in size, or in number of oysters, 

 there being a natural limit to expansion in either direction. Supposing, then, a bed to have 

 extended itself as far as the conditions of bottom ami water or other natural limit would allow, all 

 future expansion could be only in the number of oysters on the bed ; this is limited principally by 

 the amount of food and the room for development (the question of enemies not being considered, 



