302 OVARY AND INTEA-OVARIAN EGG IN TELEOSTBANS. 



he terms them, the " germinal dots,'^ move to the centre and 

 divide up. 



I am inclined to think that in the case of Teleosteans the greatest 

 amount of division takes place at the surface of the nucleus, and 

 that many of the parent nucleoli afterwards become absorbed in the 

 encroaching protoplasm. In this case the darkly stained proto- 

 plasmic ring spoken of above is in part explained. 



The vacuolated condition present in the nucleoli of Triton during 

 their division, and also described by O. Hertwig (6) in the egg of 

 Hsemopsis and Rana, and by V. la Valette St, George (7) in the egg 

 of Lihellula, is not present ; nor is there any concentration of these 

 division products into a mass in the centre of the nucleus. A 

 vesicular condition, however, which might be mistaken for vacuola- 

 tion, appears, and is described below in the case of the conger. 



The surrounding protoplasm continues to encroach on the space 

 of the former nucleus, and the central nucleoli appear to be ulti- 

 mately enveloped in this condition. They then correspond to the 

 permanent nucleus of the ripe ovum as described by Hertwig in 

 Toxojpneustes . 



In the ovary which is quite unripe, in distinguishing the three 

 generations of eggs, many intermediate stages leading from the one 

 to the other are at the same time noticeable. The largest of the 

 eggs in the common dab of this stage do not measure more than 

 four fifths of a millimetre. The nucleus of these eggs has a distinct 

 membrane, and the nucleoli are arranged in contact with its inner 

 surface, so that in section they appear in a ring inside the mem- 

 brane — the usual appearance of nucleoli in fish eggs. The ova 

 at this stage do not present so marked a contrast as they do later, 

 the proportions between the sizes being less. 



The ovary of the common dab may be found in this unripe con- 

 dition all through the autumn and winter months ; it is, therefore, 

 the condition which has been often noticed. About two months 

 before spawning takes place the great ova, which will be ripe for the 

 first spawning season, show signs of rapid enlargement, and in a 

 comparatively short time assume the appearance seen in fig. 2, 

 already described. 



I have made no direct observations on the origin of the micro- 

 pyle, and will pass over the egg in the ripe extruded condition. 

 It has been noticed (8) on more than one occasion along with the 

 ova of other Pleuronectids (9). 



I shall rather take up the consideration of the ovary after the act 

 of spawning. Great ova are then still present in limited numbers. 

 I have counted the number visible in several transverse sections, 

 and find that there are from ten to fifteen seen in each section. It 



