724 OCEANOGRAPHY 



bent, and planted with the other end on a piece of board. This, being 

 applied on another piece of plank, is forcibly pushed along the mud 

 bottom with the tooth part down, and all the tiny shells in the mud 

 are caught between the teeth of the comb and accumulated on the 

 bent ends of the wire. These are collected once in a while and put into 

 a tub, after which another raking is gone through. The distance 

 between the wires regulates the size of the shells to be caught. If 

 the interval is large, the shells caught are naturally large, and vice 

 versa. 



These tiny shells collected from various parts of the bay are 

 placed in the culture-grounds. It has been found that the best size 

 for starting culture is quite small that is, one which will go into 

 the number of 30,000 to 70,000 per "sho" (1.58 quarts or 1.8 liters). 

 In order to distribute them over the ground allotted to them, the 

 little shells which have been collected are heaped up in a boat. One 

 man rows the boat along slowly, and two others measure out the 

 shells and throw them overboard with wooden scoops. The quantity 

 of shells that can be most profitably put into a unit-area differs, of 

 course, with the size and age of the shells, and has been very carefully 

 studied out. 



The tiny shells that in September are only two to three millimeters 

 across, and run 30,000 to 70,000 to a "sho," grow by the autumn of 

 the next that is, the second year to nearly twenty millimeters 

 in length, and run only 1000 to a "sho." In the autumn of the 

 third year their average length is already thirty-two millimeters, 

 and they run only 200 to a "sho," and by the autumn of the fourth 

 year they become forty-two millimeters long, or only 120 to a "sho." 



As the shells grow, their number per unit-area must be diminished 

 to the proper number determined by previous experience, and all 

 the superfluous ones must be removed to near lots. These culture- 

 grounds show, therefore, a large number of partitioned or marked 

 areas, each of which contains a special lot as regards size and age, 

 and give one an idea of the most methodical procedure. 



It has been found that the crop of tiny shells which can be collected 

 each season differs greatly in amount with different years. For 

 instance, in 1893 the crop was very large, amounting to 14,145 

 bushels, but in the following year there were only fifteen bushels, 

 and in the two years after that matters were still worse, there being 

 practically none at all. In order, therefore, to have the market 

 supply constant, and not fluctuating as these " seed "-shells, it has 

 been found possible to retard the growth of the shells. That is, after 

 they reach a size of 2000 to a "sho," they are removed to a some- 

 what deeper place, where the current is slow and where they are, no 

 doubt, also kept more crowded than usual. This has been found 

 enough to make their growth slower, and the seed-shells collected in 



