of the Fishery Board for Scotlarid. 



Ill 



March 3. — IVc. — The eggs showed a germ in a disc stage of very small 

 cells ; cf. fig. 20. A great quantity of crystals was present inside the zona. 



March 4th. — IVc. —The egg examined was in disc stage (fig. 20). Some 

 of the eggs were dead. 



March 5th. — IVc. — The disc showed a tendency to become saucer-shaped 

 (fig. 49). Here also there was a large number of crystals. 



March 7. — A plate of IV., which had up till now been in the ordinary 

 hatchery water, was on this date transferred to cooled water. It was placed 

 horizontally, with the eggs uppermost, in an egg-box. The plate rested on 

 the top of the inclined guides, p. 102. The eggs were in the stage of 

 development exhibited in figs. 5 and 6. This plate is now labelled IVc 1 . 

 It was transferred at 2.45 p.m. from water at 4 , 3° into water at 2*6° At 

 3.30 p.m. the temperature had fallen to 1'4° C. The plate was exposed 

 momentarily to the air when being removed to its new situation. 



March 11.— IVc. — This batch consisted of three glass plates bearing eggs. 

 They were arranged in an egg-box, standing obliquely, eggs downward, as 

 shown in E, p. 102. The eggs of the first and third plates were nearly all 

 dead. On the middle plate they were nearly all alive. The dead eggs had 

 died while in the disc stage. The live eggs were mostly in the stages shown 

 in figs. 50, 51, and 6. One, however, had a germ similar to that of fig, 2. 



March 18. — IVc 1 . — The eggs were apparently doing well; a few were 

 dead. A deposit of fine mud was removed from the eggs by means of a 

 pipette. 



April 4. — IVc 1 . — Half of the eggs on this plate seemed to be alive. 

 They were very dirty. The eggs upon which the incoming water impinged 

 directly were cleaner than those situated a little away from its immediate 

 action. 



April 9. — IVc 1 . — A good number of the eggs were seen to be dead at this 

 date. The live eggs were at the stage shown in fig. 52. The eye had 

 black pigment in it. Two of the eggs which were examined seemed almost 

 ready to hatch. The dead eggs were covered with the white colonies 

 mentioned on p. 



April 14. — For most of the preceding period the water from IVc. has 

 passed into the box containing IVc 1 . By this date the order had been 

 reversed, and a trap for any larvae which might be hatched had been 

 arranged. It consisted of an ordinary hatching-box placed so as to receive 

 the outflow from IVc. 



April 15. — IVc, IVc 1 . — Four live larvae and a dead larva were obtained 

 from these eggs. They are the first fry to be noticed, and they represent 

 an incubation period of 46 days. They may have come from either IVc. or 

 IVc 1 , or from both. 



April 16. — Two live larvae were found. In IVc 1 there were some eggs 

 alive ; the majority were, however, dead. 



April 17. — One live larva appeared on this date. Some of the eggs of 

 IVc 1 were still alive. 



April 18. — Four live larvae were obtained. It seems that when the eggs 

 arrive at a condition ready for hatching a rise in temperature at once 

 liberates them. 



April 19. — No fry was obtained on this date. Some of the eggs of IVc 1 

 were still alive. The weather was colder, and the temperature of the 

 hatchery water did not rise so much as usual during the night. 



April 20. — One live larva was in the trap in the forenoon, and by 

 2.20 p.m. another had hatched out. There was a small patch of live eggs 

 on the plate of IVc 1 . They were not immediately below the inlet, but a 

 little in front, and in the direct line from the inlet to the outflow of the box. 



The last remaining plate of IVc. was examined. It had not been possible 

 to examine this plate properly since it was set in the egg-box in a slanting 



