COD-FISHERIES OF CAPE ANN. 723 



from the center, and placed at such an angle that the rotation of the cyl- 

 inder forces the water against them, and up through the bottom. The 

 whole is placed in a trough nearly filled with constantly-changing 

 water, and sunk to such a depth that the water nearly fills it. The 

 cylinder turns on a pivot, the power being applied from the engine by 

 means of shafting, to a horizontal arm firmly fixed to its axis, and is 

 kept constantly turning back and forth through an arc of 90"^, thus 

 keeping the water changing, and giving the eggs a tendency toward the 

 top center. 



When this apparatus had been thoroughly tested, and found to give 

 good results, the cones were taken down, and water-tight troughs placed 

 along the sides of the hatching-room to receive the Chester buckets, 

 and from this date the hatching operations were conducted with a fair 

 degree of success; and while, with jiure water, the modified Clark trough 

 or some equally simple apparatus might give excellent results, yet to 

 Captain Chester belongs the credit of having i)artially overcome the ex- 

 isting difficulties, and of inventing the first ajiparatus successfully used 

 in hatching floating eggs. 



The time required for the development of the egg.s of the cod-fish, after 

 they are thrown from the parent, varies greatly, being dependent largely 

 upon the temperature of the surrounding water. Of those taken Novem- 

 ber 13, the first hatched in 13 days ; while of those taken December 17, 

 the last did not hatch until February 5, thus requiring 51 days ; giving 

 a elitference of 38 days for eggs taken within little over a month of each 

 other. The period of 51 days represents an extreme case, and the cir- 

 cumstances may be worthy of consideration. These eggs, as above 

 stated, were taken December 17 from four fish apparently in good con- 

 dition, and placed in a bucket in the hatchery. January 28, the bucket 

 was thought to contain too many eggs, and a few were taken out and 

 placed in a floating box, with wire-cloth bottom, anchored in the harbor. 

 The difference in temperature of the water in the two places averaged 

 from one to two degrees. 



Of those remaining in the building, the first hatched January 17, and 

 the last on the 23d, making a variation of 6 days. 



On January 25, the first fish were noticed from the harbor lot, and from 

 that time they continued to hatch slowly until February 3, when not 

 more than 10 per cent, were out, and 2 days later, when the first fish 

 were 11 days old, and the eggs 51 days from the parent, a few still re- 

 mained unhatched. 



The variation of 11 days for eggs treated in exactly the same man- 

 ner, suggests the idea that other elements than temperature may enter 

 in to hasten or retard development. One cause, namely, that of the con- 

 dition of the eggs when thrown from the parent, may considerably afl'ect 

 this period. 



We find with the cod, as with other species, that the first fish hatched 

 from a given lot of eggs always seem weak and immature j and again, 



