of the Fishery Board for Scotland. 



109 



small groups or in big lumps. The lumps were, in some cases, quite one 

 inch in thickness and over one inch in length. There was a big proportion 

 of the eggs arranged in little groups of two, three, or more. The eggs in the 

 large lumps died early, but a large proportion of those in the little groups 

 survived and hatched. On March 17 the eggs in the largest lump were 

 practically all dead. On 23rd March the remaining lumps were nearly all 

 dead, The mass of eggs is tough, and is not readily broken. The eggs in 

 the largest lump had died early, the eggs being in the disc stage. One of 

 the smaller lumps had a few live eggs in the interior surrounded by dead 

 eggs. 



The eggs on the glass plates died in large numbers in the metal egg-boxes, 

 but a considerable proportion hatched out. 



February 29. — About twelve hours after fertilization some of the eggs 

 of IVb. were examined. They were in good condition. The perivitelline 

 space was large, and the blastodisc was segmented into two or four (fig. 48). 



March 1. — The eggs of IVb. were in the condition shown in fig. 1. 

 The disc was completely segmented. The eggs examined the previous day 

 had been left overnight in a glass cell ; they were at a similar stage. 



March 3. — TV. and IVb. — The eggs on the glass plates and also IVb. 

 at this date showed the disc in a saucer-shape of approximately the stages 

 shown in figs. 2 and 3. 



March 4. — IV. and IVb. — The eggs were not much advanced on the 

 condition found on the preceding day. They were, however, in good con- 

 dition, and the stages shown in figs. 2, 3, and 4 were exhibited by some of 

 them. There were quantities of long crystals outside and inside the egg- 

 shell. The great majority of the eggs of IVb. were alive. 



March 7. — IV. — The blastopore was closed (fig. 5). The eye was visible, 

 but the pupil was not made out. A Kupffer's vesicle was noticed. Long 

 crystals were present inside the zona. 



March 13. — IV. — The tail of the embryo almost reached the head. (Of. 

 %. 9.) 



March 17. — IVb. — One of the eggs had an embryo in which the tip of 

 the tail reached to the neck, approximately the condition shown in fig. 11. 

 In IV. there was considerable variation in the stage of development. In 

 some the end of the tail was just short of the head (e.g., a little further on 

 than fig. 9), while in others the tail reached past the head. (Of fig. 11.) 

 A great quantity of crystals was observed on the embryo and on the zona. 



March 18. — IV. — One egg was examined. At first no movement either 

 of the embryo or of the heart could be detected. After a little the heart 

 began to beat steadily, and the embryo twisted itself round in the egg. 

 This was probably in consequence of the rise in temperature due to 

 its transference to the Laboratory). The embryo lay a long time 

 passive. Next morning the egg was alive ; the heart was beating slowly but 

 vigorously. 



March 23. — IV. and IVb. — Some fry was obtained to-day from each 

 portion of the spawn — that is, after an incubation period of 23 days. On 

 this date the eggs of IVb. were transferred from one box to another, and 

 the larvae were hatching out during the operation. The movement probably 

 aided the escape of the fry from the eggs. The temperature of the water 

 was 6°. Some of the eggs were left for three-quarters of an hour in a glass 

 cell. The temperature rose to 8°. Two larvae hatched out. The egg- 

 capsules from which the fry had escaped were ruptured irregularly ; in one 

 case a piece of the zona had been taken out. The capsules were very dirty, 

 and infusors were running about them. 



March 24. — IV. and IVb. — 130 fresh larvae were counted on this date. 



March 25, 26, 27, 28.— IV. and IVb.- -Larvae were obtained. On the 

 last date some of the eggs of IVb. were still unhatched. Occasionally an 



