Fig. 86. Age and Growth. As the scallop becomes larger the rate of 

 growth, both in actual increase and gain in volume, becomes less. The three 

 columns represent the comparative gain in volume of (1) "seed" scallops (^ of an 

 inch) of the 1906 set, 200 per cent.; (2) fourteen-month scallops of the 1905 set, 

 25 per cent.; (3) twenty-six month scallops of the 1904 set, 12 per cent., under 

 the same conditions. 



Fig. 87. Current and Growth. -- The three columns represent the volu- 

 metric growth, for a definite period, of scallops in good, medium and poor currents, 

 and are formulated from measurements made at Stage harbor, Chatham, in 1906- 

 07. At the mouth of the harbor is a large eel-grass flat, extending from the shore 

 to the channel. The flat was arbitrarily divided into three areas, according to the 

 circulation of water: (1) near the channel (good current); (2) half-way to shore 

 (medium current) ; (3) near shore (poor current) ; and the rate of growth of the 1906 

 set was followed in each division. These figures demonstrate the great importance 

 of current in scallop growth. 



Fig. 88. Current and Growth. --The influence of current is again illus- 

 trated by comparing the volumetric growth of "seed" scallops of the same size at 

 (1) the raft, Monomoy Point (good current), 662 per cent.; (2) Stage harbor, 

 Chatham (medium current), 475 per cent.; (3) south side of Powder Hole, Mono- 

 moy Point (poor current), 293 per cent.; (4) east side of Powder Hole (no cur- 

 rent), 98 per cent. The comparative volumetric growth for a period of seventy-six 

 days during the summer of 1906 is represented for each of these localities by the 

 shaded columns. A knowledge of the relation of current to growth should prove 

 valuable to the prospective scallop culturist. 



