OF MASSACHUSETTS. 75 



The general work consisted of two parts : (1) at Monomoy Point on 

 the scallops confined in the Powder Hole; (2) records of the growth- 

 of the different sets at different localities along the southern coast of 

 the Commonwealth. The investigations were first started in July, 1905, 

 and continued steadily through 1906 and 1907. Records were also 

 maintained in several localities for 1908 and 1909, while the work at 

 Monomoy Point was continuous for the whole period. During this 

 time records of the complete sets of 1904 (second year), 1905, 1906, 

 1907, 1908 were made at Monomoy, and for the State in 1904, 1905 

 and 1906. Another division of the work of a different nature can be 

 made: (1) experiments in artificial culture, where the scallops were 

 confined in pens of wire netting at Monomoy, Marion, Monument Beach 

 and Chatham; (2) records of the growth under natural conditions on 

 the scallop grounds by measuring large numbers of scallops. A descrip- 

 tion of the methods of work, details of measuring, construction of pens, 

 marking of scallops, etc., is given in chapter VII. 



General Growth. — The shell or exo-skeleton of the scallop is com- 

 monly considered the growing part and any increase in its size indicates 

 the development of the animal. New shell formation is the direct 

 result of a previous corresponding growth in the soft parts, whereby 

 an extension of the shell is necessitated. In the following experiments 

 the shell has been considered as typifying the development of the body, 

 and all measurements have been recorded on this basis. The quality 

 of the meat and the fattening of the tissues, so .important to dealer, are 

 not considered under the subject of growth, but are discussed in con- 

 nection with the " eye " in chapter VI. 



Shell formation by the secretion of the thin mantle lining the inside 

 of the shell has been described in chapter 11. The shell is built almost 

 entirely of lime salts (principally the carbonates), which is obtained in 

 some unknown manner from the water. It appears that the amount of 

 lime in solution in the water is an important factor in the rapidity of 

 growth, but is not as essential as the nourishment of the soft parts by 

 the microscopic food. The actual increase in the rate of growth by an 

 excess of lime is but slight, as the shell formation naturally depends 

 upon the growth of the soft parts, and the difference is only evidenced 

 by the increased weight of the shell in localities rich in lime salts. The 

 lime supply varies somewhat in the different localities, and its efl&ciency 

 is largely dependent upon the circulation of water. 



In considering the rate of growth the matter of food is of chief im- 

 portance. Within limits the growth of any mollusk is directly propor- 

 tional to the amount of food it consumes. Scallops situated in good 

 feeding localities will grow much faster than those less fortunately 

 located. The food as stated in chapter IV. consists of microscopic 

 plant forms, called diatoms, which are uniformly distributed through the 

 water. Naturally the abundance of diatoms in any locality and the 



