120 J. T. GUJS'NlNUnAM. 



very corumouly, if not always, iu immature ovaries. I have 

 seen them in abundance in numbers of specimens of plaice 

 examined in November and December, in which no healthy 

 yolked eggs were to be seen ; and at that time of the year the 

 ovaries of all mature specimens are full of eggs in which the 

 development of yolk is far advanced. At the same time none 

 of the plaice have begun to spawn, and no spent fish are to be 

 found. The specimens, therefore, whose ovaries have not begun 

 to mature in those two months, could not spawn until the next 

 season, and are therefore immature. 



I have prepared sections from an ovary with dead yolked 

 eggs belonging to a plaice obtained in Grimsby market on 

 August 3rd, 1895. The specimen was 11 1- inches long, and was 

 caught on grounds not far from the Humber. As no speci- 

 mens less than 13 inches long from that part of the North Sea 

 have been found to be mature, it may be concluded that this 

 specimen had never spawned. In the sections, eggs in three 

 different conditions are seen. (1) Tliere are small eggs of 

 healthy appearance, entirely protoplasmic, and, as is usual with 

 such young eggs, deeply stained with hsematoxylin. These are 

 from '04 to '11 mm. iu diameter, and have a normal and healthy 

 structure. The germinal vesicle in them has a regular definite 

 circular outline with nucleoli arranged round the periphery. 

 These young ova are not very numerous ; they are distributed 

 singly just within the surface of the ovarian lamellae. (2) 

 There are next a number of larger eggs much less deeply 

 stained, and having a granular appearance ; the largest of 

 these are about "18 mm. iu diameter. There can be no doubt 

 that these are the largest transparent eggs seen in the fresh 

 condition of the same material. No yolk was visible in the 

 fresh condition, and none can be seen in the sections. But 

 the granular condition of the protoplasm, especially at the 

 periphery, indicates that these eggs have reached that stage 

 of maturation at which the deposition of yolk is about to com- 

 mence. The material was obtained from the market, and 

 therefore not preserved till some time after the death of the 

 fish. This doubtless accounts for the fact that in many of 



