OYSTERS AND METHODS OF OYSTER-CULTURE. 311 



equal amount of care has beea expended, will prove utterly sterile. 

 While in many such cases the causes are not known, yet the experience 

 of j)lantin<? has thrown some light upon the matter. It is known that 

 cultch can not be thrown down at random with any strong expectation 

 of success. The water is not everywhere charged with the swimming 

 fry, and the experience of planters has shown that they are often dis- 

 tributed in streaks or belts, which appear, to some extent, at least, to 

 be conditioned by the currents. If cultch be placed in a current it will, 

 other things being equal, be more likely to catch a set than when in 

 still water. Even a strong current does not appear to interfere with 

 the fixation of the young, and as it brings a greater body of water into 

 contact with the collecting surface, some of it is more likely to contain 

 fry at the stage for fixation. 



It is also obvious that the water is not likely to contain many fry 

 unless there are spawning oysters in the vicinity, and it is, therefore, 

 the part of wisdom to locate the collectors in the vicinity of natural 

 or artificial beds containing mature oysters. Even where the oysters 

 are so scattered as to hardly pay for working, it will be usually found 

 that there is suflQcient spawn fertilized to provide considerable seed if 

 it be given proper facilities for attachment. For reasons readily seen, 

 it will be advantageous to locate the collectors so that the predominating 

 current sweeps from the spawning oysters toward the collectors. In 

 some localities it will be found that the entire set occurs in the tidal 

 zone; that is, in the area between low and high water. The reason for 

 this is not yet fully understood, but if it should prove to be because the 

 embryo oyster is lighter than the dense sea water, and therefore can 

 not sink to the bottom, or because the sedimentation is too rapid 

 below low-water mark, or almost any other reason except the softness 

 of the bottom, then the cultch must be confined to the area between 

 tides if it is to be ettectual as a collector of spat. The most careful and 

 uniformly successful oyster-culturists do not depend entirely upon the 

 spawn derived from neighboring beds, but usually distribute over the 

 spatting-beds a number of mature spawning oysters in the proportion 

 of 30 to CO bushels per acre, these being usually put down before the 

 cultch, so that the oysters will beconio ^'^ ^ome extent acclimated before 

 the spawning season. 



As the cultivated area increases it becomes unnecessary to use so 

 many brood oysters, and in some places where they were formerly used 

 reliance is now placed solely upon the tioating fry* derived from the 

 mature oysters on neighboring beds. Upon theoretical grounds it would 

 appear to be preferable not to scatter these " mother oysters" too widely. 

 There would seem to be greater certainty of fertilization when the 

 oysters are grouped, and there are ample time and superior facilities 

 for securing distribution over tlie beds in the embryonic condition. 

 The embryo exists for a period as a free-swimming form, and during 

 that time it may be carried considerable distances by its own exertions 



