32 NORTH SEA INVESTIGATIONS. 



In all the fish hitherto mentioned there are no oil globules in 

 the ripe egg, and the develoitment of the yolk follows the 

 course which I have described in my two papers, vol iii. pp. 

 154 and 2.58. In all these cases I have satisfied myself that the 

 development of the yolk in the eggs takes less than a year. In 

 other words the formation of the crop of eggs for the next spawning 

 season does not begin until some time, about three or four months, 

 after the preceding spawning. But in my paper, vol. iii, no. 2, I 

 described in the egg of the sole the presence of minute globules in the 

 ova of immature females during the spawning season, and in spent 

 females. Recent observations have shown me that these minute 

 globules occur only in those eggs in which oil globules are present 

 in the ripe condition, and I conclude that the deposit of oily matter 

 commences in the ova long before that of yolk proper. 



On April 8th I examined 3 small brill, procured from a lot of 

 34, brought with 4 small turbots and 120 boxes of small plaice 

 from the Sylt Grounds. One was 9} in. long, a male not ripe, but 

 with testes rather large and soft, evidently approaching ripeness. One 

 was 11^ in., a ripe male. One was Hi in., a female, the end of the 

 ovary 4] in. from the anterior end, 4^ from the posterior end of the 

 ventral fin. All the ova under the microscope were transparent, 

 but except in the very smallest there were small, clear globules, 

 principally collected round the germinal vesicle. I think this specimen 

 could not have matured its eggs during the present spawning season, 

 and would not have been ripe for at least 12 months. On April 22nd 

 I examined another specimen, 15 in. long, in which the left ovary was 

 3^- in. long and 5 in. from the end of the ventral fin. There was 

 nothing to indicate that this specimen was spent, all the ova were 

 transparent, but here and there one showed the scattered globules 

 I have mentioned. This specimen was presumably immature. 



On April 24th I examined the ovaries of two turbot. One was 19f in. 

 long. The roe was opaque white from the development of yolk, 

 and obviously approaching maturity. Under the microscope the 

 yolk in the eggs was in all stages of development. In some there 

 were only the peculiar globules I have mentioned, in others a little 

 larger, these were more numerous, and began to form a dark zone 

 round the germinal vesicle, while in the outer part of the egg were 

 globules of ordinary yolk of a much lighter appearance. In all 

 the eggs in which the development of yolk was considerable, there 

 was an inner darker and an outer lighter zone. The other specimen 

 was 15\ in. long, and the formation of the dark inner zone had 

 commenced in an egg here and there. Apparently this specimen 

 would have spawned this season. 



