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Part III — Twenty-seventh Annual Report 



position. It was necessary in this case to lift the slide out of the water 

 and transfer it to a tray containing water before it could be examined. 

 This was avoided in case the exposure of the eggs to the air might injure 

 them. No live eggs were at this date found on the plate. The eggs weie 

 all much swollen and dirty. They were covered with a layer of white 

 patches (vide p. 107). In some places the growth had a pinkish colouration. 

 The contents of nearly all the eggs had disappeared. When the eggs were 

 scraped off the plate, a few dead larvae were turned out. One appeared to 

 have been ready to hatch, and others were in the stage where the tip of the 

 tail reached to the back of the head (c/. fig. 11). Two eggs contained 

 larvae which were so recently dead that they were still in greater part trans- 

 parent. The eggs of IYc 1 alone remained from this date. 



April 21. — No fry was obtained. Live eggs were, however, noticed. 



April 22. — One live larva was got on this date. 



April 23. — No fry appeared. There were still a few live eggs. 



April 24. — No live fry was found. One live egg was seen. The plate of 

 IVc 1 was shifted from the cooled water to the uncooled hatchery water 

 (4-8° C). 



April 25. — One larva was obtained. It was in good condition. Some 

 eggs appeared to be still surviving. 



April 26, 27, 28 ; 29.— No fry was obtained. On the 29th a live egg was 

 observed. 



April 30. — No fry was found. All the eggs on the plate were dead. 

 They were covered with a thick coat of debris. Many of the embryos had 

 died about the stage of the closure of the blastopore. 



The fry then appeared at intervals of from 46 to 55 days after fertilization. 



IVc 2 . — March 18. — This plate of eggs had been kept at the ordinary 

 temperature of the hatchery water in one of the metal egg-boxes. The 

 great majority of the eggs were alive. The temperature of the water was 

 4*2°. The plate of eggs was cooled to 2° and then transferred to a 

 hatching-box supplied with cooled water of 1*2° C. It was retained in the 

 cooled water until the eggs hatched. One of the eggs was examined and 

 found to be in the stage represented by fig. 53. The tip of the tail reached 

 to the neck region. The yolk was being rapidly absorbed, and showed the 

 little peaks on the periblast very distinctly. An egg was examined after 

 the plate had been in the cooled water for an hour. The embryo was very 

 quiet ; the heart was giving an occasional contraction. It beat for about 

 half a minute, making during that time about six contractions: ; it then 

 rested for one minute 49 sees., when it started again. During the time it 

 was in the watch-glass the temperature may have risen. 



March 24. — Two eggs of this lot on this date seemed to be ready to hatch. 

 They were examined immediately on being removed to the Laboratory. 

 The heart was beating steadily. The eggs lived in the glass cell till the 

 27th, when both appeared to be dead. Neither had hatched, although one 

 of them when seen on the 28th had managed to get its head out. 



March 29.— Fourteen larvae were obtained from this batch of eggs. 

 They were not very active, although they wriggled a little. 



March 30. — Forty more larvae had appeared. 



April 1. — No fry was obtained on this date. The plate of eggs was 

 shifted from water at 2° into a new situation where the water was at 2*8° C. 

 Some of the eggs were dead, but the majority was alive and unhatched. 

 From this date onwards the water supplied to these eggs was warmer than 

 before. 



April 2, 3, 4, 5, 6, 7, 8, 9, 10. — Larvae were obtained on each of these 

 dates. On April 2, 55 were got ; on April 9, 70, and on the 10th, 20. On 

 the 5th, 6th, 7th, and 9th the fry was noticeably rather livelier than on the 

 other dates. 



