of the Fishery Board for Scotland. 



97 



I have stated that I examined large numbers of the eggs in the fresh 

 condition, and I may here describe the appearance of some of the smaller 

 ones. In specimens corresponding to the sizes I have been dealing with, 

 the germinal vesicle is very prominent, and the nucleoli conspicuous as 

 highly refringent faintly greenish bodies, appearing rather larger than in 

 mounted sections. In some cases in which the nucleus was isolated, its 

 surface was kiiobbed by the projecting nucleoli. The features were most 

 carefully studied in the eggs of the Norwegian topknot {Zeugopterus 

 norvegicus), caught on 25th April. In an egg measuring 0"06mm., and 

 magnified 360 diameters, only one nucleolus was observed, which was 

 very large and conspicuous, and on focussing downwards it presented 

 optical alternations of light and shade suggesting an irregular pyramidal 

 form. Near the nucleus were two bright points, probably droplets 

 of oil. In eggs somewhat larger (0'13 to 0*1 6mm.) the cytoplasm 

 showed very distinctly the division into two zones described by 

 Ransom,* Scharff,t Bambeke,i and others, the inner zone being 

 darker and exhibiting a coarsely reticulated structure, and the outer 

 zone lighter, with a fainter reticulated appearance. The intra- 

 nuclear network is visible, and around the nucleus in the inner zone 

 several bright points are present, which are probably oil. In eggs still 

 larger, measuring from about 0*1 9mm., the inner zone is seen to be 

 occupied by a great number of minute refringent globules, which are 

 also scattered over the surface of the germinal vesicle. At earlier stages 

 the appearance of the ovum does not specially indicate, in these fresh 

 specimens, a spherical form ; but now this is a marked feature, the 

 germinal vesicle, which is large, measuring sometimes half the diameter, 

 stands out boldly as a translucent globe encompassed by a gradually 

 darkening ring, which obscures its periphery and shades off into the 

 lighter area towards the margin of the egg. The dark part of the ring 

 may measure about 0"02mm. This condition becomes more obvious in 

 larger eggs, the germinal vesicle becoming quite obscured by the 

 prominent globules, which are obviously of an oily nature, and vary 

 considerably in size. 



On examining a section from the same ovary (which contained fully 

 mature eggs), hardened in picro-sulphuric acid, and stained with haema- 

 toxylin, safEranin, and eosin, the minute ova, about 0 06mm., show the 

 usual highly-stained protoplasm around the nucleus, but I was unable to 

 detect the large conspicuous nucleolus seen in the fresh egg. The nucleus 

 under a high magnification (Zeiss, 4mm. apochr. oc. 12) shows a coarse 

 intra-nuclear network with a finely granular lighter matrix ; nucleoli are 

 by no means conspicuous, and are difficult to discriminate from nodes in 

 the network. In larger eggs, from about 0*16 mm., the cytoplasm around 

 the germinal vesicle was vacuolated, empty spaces of very various sizes 

 existing in the protoplasm. The vacuolation in those in which it is least 

 marked is not quite in contact with the germinal vesicle, but a slight 

 distance from it ; but in eggs a little larger it is close up to it, and extends 

 for some distance into the cytoplasm. 



This condition is due to the early formation of oil-globules in the 

 peri-nuclear zone. It has been described in the eggs of the eel by 

 Owsiannikow§ and Williamson, || in those of Fierasfer by Emery,i[ and 

 most fully by Cunningham** in the eggs of the gurnard, brill, turljot, and 

 sole. I have also found the condition present in the species mentioned 



* Op. cit. t Op. cit. X A-rch. de Biologic, xiii., p. 88 . 1898. 



§ Mem. I' Acad. Imper. des Set. de St. Petersburg, vii. ser., Tovie xxxiv., JVo. 4, p. 28. 1885. 

 II Thirteenth Annual Report Fishery Board for Scotland, Part Hi., p. 192. % Op. cit. 

 ** (^uart. Journ. Micr. Sci., Vol. xl., p. 101. 



