of the Fishery Board for Scotland. 



227 



free nuclei were in the protoplasmic belt (periblast) around the disc. It 

 seemed as if a somewhat abnormal activity, due to external conditions, had 

 ensued in the eggs thus transported. In some, the outlines of the spheres 

 were invisible in the central area, though the nuclei were sufficiently 

 evident, while those at the margins (fig. 3) presented elevated contours, 

 some being almost isolated from the disc. By-and-by, the nuclei became 

 less distinct. That the condition of the disc was somewhat abnormal 

 was shown by the death of the entire series before next morning. 



Another series, fertilised on 21st June at 5 p.m., and which bore the 

 journey and the heat more satisfactorily, presented at the twenty -fourth 

 hour, viz., about 5 p.m. on the 22nd, the germinal area and embryonic shield 

 (Plate VIII. fig. 5). As the embryo became outlined next day (23rd), a 

 teudency to the formation of numerous large vesicles (at the ordinary site 

 of Kupffer's, and extending in groups forward along the body) was a 

 conspicuous feature (Plate VIII. figs. 6 and 7). How far this was due 

 to the vicissitudes which the eggs had encountered is an open question, 

 but it was pronounced. On the 24th June, the embryo was distinctly 

 outlined with optic vesicles, lenses, cardiac thickening, and other features ; 

 and the large vesicles found at the time of Kupffer's vesicle were fewer ; 

 in some, two in front and a smaller vesicle posteriorly (Kupffer's). 

 Moreover, a series of chromatophores is thickly dotted along the trunk, 

 and a few over the brain, but no colour is yet visible under a lens, though 

 the embryo is indicated by a distinct opacity. 



On the 25th June, the eggs presented a slightly reddish hue under a lens. 

 It was also interesting to note that the diameter of some of the eggs had 

 increased in the direction of the long axis of the embryo, so that they 

 were ovoid (Plate VIII. fig. 8). The head and body were studded with 

 rounded, reddish (ruby-red by transmitted li'ght) chromatophores, several, 

 however, being feebly tinted. Some extended here and there over the 

 yolk, while others faintly tinted or quite pale were present. The oil- 

 globule had a few black chromatophores in its protoplasmic investment. 

 The otocysts were well formed, the lenses distinct, and the heart pulsated 

 feebly at intervals. The tail had extended considerably beyond the yolk, 

 yet one or two vesicles occurred on the site of Kupffer's. The yolk had a 

 streaky granular aspect, probably from the development of the minute 

 vesicles on its surface. The notochord was multicellular. 



Next day (26th), the pigment-corpuscles presented a deeper ruby-red, 

 and black chromatophores had also appeared (Plate VIII. fig. 9). The 

 pectoral expansions were distinct, the vesicles have disappeared from the 

 ventral aspect of the trunk of the embryo, while the tail is longer and has 

 a few black corpuscles near the tip. The black pigment at the oil- 

 globule has increased. The heart beats more regularly. The yolk has 

 considerably diminished — with thread-like bands projecting here and there 

 from its margin. Only a few red chromatophores exist in the minute 

 vesicular yolk-sac, and one or two stellate black corpuscles. The latter 

 seem to form a band along the body-lines superiorly and interiorly. 



On the 27th June, the embryo under a lens appeared to be of a brick- 

 red colour from the branching of the chromatophores, and ramified black 

 pigment is also present, especially posteriorly, where it has much 

 increased. The eyes are somewhat darker. The yolk has still further 

 diminished. 



Most of the eggs hatched about the 6th-7th day, the larval turbot 

 between the 1st and 2nd day having the aspect shown in PI. VIII. fig. 11. 

 The increase in the red pigment is characteristic, the body under a lens 

 having a brick-red hue with black chromatophores scattered over the surface. 

 The rounded, reddish chromatophores of the embryo had now largely 

 increased their branches, on the head, trunk, two caudal bars, and the 



