78 THE SCALLOP FISHERY 



covering several years, the necessary data for the actual substantiation 

 of the popular theory, and for the establishment of proper legislation 

 for the fishery. 



The method of work consisted primarily of continued observations on 

 the sets of 1905, 1906 and 1907, following each from birth to death. 

 The greater part of the work was done in connection with the growth 

 experiments in the different scalloping areas, but more particularly 

 with the scallops confined in the Powder Hole at Monomoy Point, 

 where favorable opportunity was afforded for obtaining data on the life 

 of the scallop. An inclosed, protected body of water, forming a natural 

 aquarium of five acres, from which the scallops could not escape; un- 

 molested, owing to its being leased by the State for scientific investiga- 

 tion ; a natural scallop bed with all normal conditions, yet small enough 

 for direct control and observation, were all factors which rendered 

 the Powder Hole of especial advantage for the solution of this problem. 

 Three sets of scallops were closely followed from birth to death under 

 natural conditions, free from many natural enemies and the interference 

 of man, and practically unable to escape. Likewise, scallops were con- 

 fined in wire pens for two successive seasons and the actual death-rate 

 of the old and young scallops compared under the same conditions. 



The life of the scallop can be arranged in four arbitrary stages: 



(1) embryonic life or babyhood, from the time the egg becomes a living 

 organism until the animal attaches to the friendly blade of eel grass; 



(2) adolescence, or the period ending when it first spawns at the age 

 of one year; (3) the adult period, from twelve to twenty months, 

 during the later part of which it is ready for the market; (4) senility 

 or old age, from twenty months until the animal dies. 



This last period, that of senility, is the important factor in consider- 

 ing the length of life of the scallop, as it is the time of physical decline. 

 Old age is marked in the scallop by (1) slower growth and a slight 

 thickening in shell formation for those specimens which live over 

 twenty-three months; (2) a degeneration in the large adductor muscle 

 or "eye," shown by flabbiness and diminution in relative size; (3) an 

 increasing amount of foreign growth on the shell. One or more of these 

 signs may be absent in individual specimens, but all are true of the 

 general type. Old scallops are more sensitive or susceptible to adverse 

 conditions than the scallops a year younger, and perish under condi- 

 tions which would be survived by the latter. 



The period of senility has no definite beginning. Possibly the scallop 

 is on the dec-line during its adult life, having reached its maximum 

 at the spawning season, and then, having outlived its usefulness, awaits 

 death. One of the fundamental principles of nature according to the 

 old school, as applied to the lower animals, is that life exists only so 

 far as it concerns the reproduction of the species, and that animals, 

 such as the mayfly, live only until they reproduce, and then perish. 



