18 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Lot D consisted of 109,000 eggs, yielded by two females taken in the 

 trap net of Mr. Sennett, June 26. Sperm and ova mixed at 5.15 p. m. 

 All of the eggs were fertilized and in the 4-cen stage when examined 

 on board the sliip shortly after 7 p. m. All were placed in a McDonald 

 cod-box, in which they floated buoyantly in water of a density of 

 1.0221. The eggs were allowed to remain without change all through 

 the next day and until the morning of June 28, when, at the age of 40 

 hours, they were approaching the period of development when, accord- 

 ing to previous observations, they might be expected to pass into sus- 

 pension. Up to this time the mortality had been very small, and was 

 chiefly the result of eggs having adhered to the somewhat rough 

 wooden sides or the corners of the McDonald boxes, when they were 

 left high and dry by the receding water and killed. 



At 11 a. m. on June 28, at which time the blastopore had just closed, 

 three lots of eggs, estimated to contain 25,000 each, were removed from 

 the McDonald box and subjected to the following conditions: One lot, 

 designated as sublot DA, was placed in a second McDonald box under 

 conditions precisely similar to the first, and was retained as a check on 

 the other sublots. 



A second sublot, designated as BB, was placed in an apparatus 

 designed to imitate the Chester tidal boxes and jar, arranged by cutting 

 the bottom out of a 2-quart Mason butter jar, tying cheesecloth over both 

 ends, and placing this upright in a pail ijrovided with a siphon hose. 

 The eggs were placed within the glass cylinder in water which had been 

 gradually increased in density, and the apparatus then supplied with 

 water, the density of which had been raised by adding a solution af 

 rock salt to 1.0252, this having been i)reviously determined to be the 

 density in which the eggs would just float at this period of their devel- 

 opment. About 500 gallons of this density of water, sufficient to fill 

 one of the large deck boxes, was made up to supply the apparatus. 

 After the height and rate of the tidal flow had been adjusted to that 

 customarily adopted for the McDonald boxes, the apparatus was left 

 to itself, except that it was necessary to replace the water in the supply 

 tank and aerate it about every 12 hours. 



The third sublot, designated DC, was also passed gradually into the 

 water of 1.0252 density, and then placed in a box provided with cheese- 

 cloth bottom, which was floated in the supply box of high-density water 

 on deck. 



The history of these three sublets briefly told is as follows: During 

 the next 24 hours, those comprising DA had gradually settled, becom- 

 ing distributed all through the water and on the bottom, although the 

 density had increased to 1.0226. The eggs were alive and the oil- 

 sphere had begun to be absorbed. In sublot BB the eggs all floated 

 in a compact layer at the surface of the water. They were slightly 

 more advanced in C velopment than BA and the oil-drop was smaller. 

 Of sublot BC many of the eggs had been killed by rupture of the mem- 

 brane or other injury caused by striking or sticking to the sides of the 

 box while washing to and fro in the tank. 



