The economic utilization of this scientific knowledge is as follows: shells offer a very good surface for the attachment of the young oyster, and many thousand bushels are annually strewn over the bottom previous to the spawning season. Considerable judgment is needed in choosing the right time to plant these shells, which after a few weeks in the water become so coated with slime that fixation of the "spat" becomes impossible. In Massachusetts the area between high and low water mark has been found by experiment to be the most valuable territory for this purpose, as shells planted here collect the heaviest set and can be handled with the least expense. A projecting sand bar or point with a current is also well adapted for catching oyster spat. The scallop shell is the most serviceable in spat collecting, because it is more brittle, and the clusters of oysters when attached are readily broken apart. After the oysterman has obtained a successful set, he allows the young oysters to obtain a suitable growth before he makes a final planting, either in the spring or fall. III. _Size of the "Seed" used for Planting._--While many oysters are raised from native spat in the Buzzards Bay district, the greater part of the seed is purchased in Connecticut and Long Island, and is carried in schooners or steamers to Massachusetts waters. The usual price ranges from 35 cents to $1 per bushel, according to size and quality. The oystermen cannot always choose the size of "seed" they desire for planting, as the set of any one year is very uncertain, and several seasons may pass before a large quantity of "seed" can be obtained. Thus the oyster planters are forced to take whatever size they can obtain, whether it be two, three or four year old "seed." As a rule, the small "seed" is most in demand, as it means relatively faster growth and less money invested. Often, when the ground is most favorable for fattening, large oysters are preferred for planting, and certain oystermen make this line of work a specialty. Certain localities where there is plenty of lime in the water are well adapted for growth, and yet produce poor-"meated" oysters, while in other grounds the reverse is true. The oystermen occasionally by a double transfer utilize both grounds, planting oyster "seed" for the first few years in the rapid-growing localities, and then transplanting the large oysters to the "fattening" ground six months before marketing.