126 THE SCALLOP FISHERY 



drawings, various micrometers, preparations, fixatives, etc., were em- 

 ployed, while the material was obtained in a variety of ways, as is 

 hereafter described. The investigation on the life history was car- 

 ried on at Monomoy Point during the summers of 1906, 1907, 1908, 

 and 1909, and at Wellfleet in 1908. Only those methods are here 

 described which especially apply to the scallop or show some pecu- 

 liarity which rendered them of value in this investigation. 



Method of measuring the Scallop Efift. - - The size of the mature 

 scallop eggs was determined with the aid of camera lucida drawings 

 and a standard stage micrometer. This work was done with oculars 

 1 and 2 and objectives % and %, Bausch and Lomb microscope, the 

 camera lucida and stage micrometer also being obtained from the 

 same firm. The average measurements of several batches of eggs, 

 hatched in 1906 at Monomoy Point, just previous to fertilization, gave 

 the long diameter as Vis.ss millimeter (%96 of an inch) and the short 

 diameter as HG.GG millimeter ( a /423 of an inch). These measurements 

 do not correspond with those made by Risser (2), who found the 

 size to be %ooo of an inch, or about one-fifteenth as large as the meas- 

 urements made in this investigation. 



Method of determining the Number of Eggs produced ~by the Aver- 

 age Scallop in One Season. -- How many eggs does a scallop contain 

 at time of spawning? The answer varies with the size of the scallop, 

 a large specimen possessing many times the number in a small one. 

 For the purpose of determining two sizes were used, (1) small, 40 

 millimeters (1% inches), (2) large, 68 millimeters (2% inches). Tak- 

 ing M.6 of a millimeter (Vioo of an inch) as the average diameter of 

 a scallop egg, the number of eggs in a cubic millimeter can be esti- 

 mated as 4,096, and as there are 1,000 cubic millimeters to 1 cubic 

 centimeter, there would be 4,096,000 eggs to 1 cubic centimeter. As 

 it is estimated that one-fourth of the volume is taken up by egg cap- 

 sules and tissue, it can be safely stated that there are at least 3,000,000 

 eggs to 1 cubic centimeter. The second operation consists in remov- 

 ing the ovaries from a number of scallops of a given size and meas- 

 uring them in graduates to determine the volume of the average 

 ovary. From this data the average number of eggs that a scallop 

 of any size is capable of producing can be readily calculated. Twenty 

 ovaries of scallops measuring 40.15 millimeters in size made 10 cubic 

 centimeters, one specimen thus averaging ^ cubic centimeter. There- 

 fore, a 40-millimeter scallop can produce about 1,500,000 eggs in a 

 season. The average of seven 68-millimeter scallops made the ovaries 

 of one equal to 1% cubic centimeters. Therefore, a 68-millimeter (2.7 

 inches) scallop may produce in a season 4,285,700 eggs. 



At best this calculation is only an estimate. Exactness would be of 

 little practical value. The errors which arise are as follows: (1) In 

 computing the number of eggs to the cubic millimeter the eggs are 



