OF MASSACHUSETTS. 91 



(b) Groicth and Soil It is impossible to state definitely the exad 

 effect of soil upon the growth of the scallop. The character of the 

 botiom apparently affects the growth but little, as the scallop rests only 

 on the surface and is conslanlly shifting its position. In this \\ay the 

 scallop is different from the <|iiahaug and clam, which lie buried under 

 the surface. While the adul! scallop is little affected by the nature 

 of the soil, the yomi- scallop would soon perish in soft mud were it not 

 an ached to eel grass during the early period of its life. The best bottom 

 seems to be a tenacious sand (sand with a slight mixture of mud) with 

 thin eel urass. The most common type, that of the shallow flats, is of a 

 sandy nature with various thicknesses of eel grass. In the case of the 

 lame channel scallop, the soil is either sand, gravel, hard mud, shells, 

 with but little eel grass. 



The only means of influencing the growth is by the action of the 

 organic acids in certain soils which affect the chemical composition of 

 the lower valve, the only part of the scallop in contact with the soil. 

 Sometimes in cold weather the scallop sinks down in little hollows in 

 the soil, bringing more surface in contact with the bottom. Fortu- 

 nately, localities of injurious nature are of infrequent occurrence on the 

 scallop grounds and are limited in extent. 



(c) Growth in Eel Grass. The soil indirectly affects the growth of 

 the scallop by the production of eel grass, which is found in more or 

 less abundance on the scallop beds. Eel grass, especially on the shallow 

 ilais, occurs either as (1) thick clusters with open spaces intervening, 

 (2) thinly scattered or (3) thick masses. Only in the last case is eel 

 grass a serious check to growth, as it then cuts off a proper circulation 

 of water, which is the main essential for rapid development, although 

 in the other two types there is more or less interference, according to the 

 thickness of the eel grass. By a comparison between growth on clear 

 sand bottom and in thick eel grass, where other conditions were approxi- 

 mately the same, the scallops on the clear bottom show a greater rapidity 

 of growth than those within the grass, showing that the difference was 

 mainly due to a lack of circulation. 



(d) Effect of Temperature. --The factor next in importance to cur- 

 rent in determining the growth of the scallop is temperature. The 

 scallop needs a temperature over 45 F. for growth, thus differentiating 

 the growing months (May 1 to December 1) from the winter months 

 (Fig. 80). Naturally, cessation of growth would be attributed to a 

 lack of food. While by actual count there is a decrease in the amount 

 of food (diatoms) in the water about December 1, it is not sufficient to 

 account for the cessation of growth at this date. Indications point to 

 the fact that the activity of the scallop in procuring food has declined, 

 as the animal has become sluggish with a lowering of the water tempera- 

 ture, and during the winter months remains inert on the bottom, nestling 

 in little hollows in the sandy soil. 



