of the Fishery Board for Scotland. 



vacuoles —obviously derived from the fusion of yolk-spherules — were 

 very large, one measuring 0*27mm., and of unequal size ; their interior 

 sometimes, but not usually, contained a few scattered granules. The 

 egg was not transparent, but it was translucent, and no clearer spot 

 indicated the presence of a germinal vesicle. On focussing down, a large, 

 faint, but definite circle was observed (Fig. 20). Other eggs, trans- 

 parent and full-sized, presented the appearance shown in Figs. 21-24. 

 In Fig. 21 the vesicle h was faintly and finely dotted, and contained one 

 small refringent body. In Fig. 22 more small vesicles were present at the 

 periphery, some of the largest measuring 0*1 1mm.; 23 and 24 show other 

 appearances. The latter was treated with dilute acetic acid, a few drops 

 of 5 per cent, solution being added to the ovarian fluid in which the eggs 

 were lying, and the spot a became dark, while the rest remained 

 unaltered. Many other eggs exhibited similar characters. 



The interpretation of all the appearances is not clear. There is little 

 doubt the vesicles aggregated at the periphery of the large vesicle repre- 

 sent yolk-spherules which have fused, but the other features are not 

 easy to explain. They are not the ordinary changes which occur after 

 the death of normal mature eggs, as I showed by experiment in those of 

 the flounder for this purpose, as well as in those of the plaice, to ascer- 

 tain the post-mortem changes associated with loss of buoyancy. 



In the egg of the angler I have been able to examine the germinal 

 vesicle in the process of dissolution. The condition of the germinal 

 vesicle in some of the larger eggs containing normal yolk-spherules has 

 been already explained. In the ovary of a fish containing ripe eggs I 

 found some as represented in Fig. 13, PI. II. The germinal vesicle 

 of the central egg in this figure is shown in Fig. 4, PI. III., as it appears 

 under Zeiss oil-immersion lens 2mm., and compensating ocular 4, 

 with the tube drawn out. In these eggs it will be seen that the yolk- 

 spherules have fused to a considerable extent, owing to the entrance of 

 the follicular fluid ; and in the egg under consideration the germinal 

 vesicle has moved to the side of the egg-capsule (a), and is obviously 

 disintegrating. It is irregular in shape, the bounding membrane has 

 disappeared, except, perhaps, at the part furthest from the egg-capsule, 

 where the margin is in parts regular in outline, and a faint double 

 contour can here and there be made out. At the outer part the sub- 

 stance of the germinal vesicle is continuous with the very scanty 

 cortical protoplasm, and is apparently fusing with it. The ground 

 substance of the vesicle has a granular appearance, but careful exami- 

 nation in a good light shows that it is composed of a fine irregular 

 meshwork of granular threads, which are made more obvious with 

 compensating ocular 12 ( = 1440 diameters), and are specially noticeable 

 at the frayed margin and at the thin part near the zona radiata. The 

 threads have not, however, the regularity of moniliform pattern shown 

 in Fig. 5, PI. III. ; they appear somewhat shrunken. The most notable 

 feature is the presence of very numerous spherical granules, vesicles, or 

 corpuscles slightly stained, some more than others, contained among the 

 meshes of the network. These may be seen here and there throughout 

 the whole substance of the vesicle, but they are mostly aggregated in the 

 neighbourhood of the nucleoli which are near the zona radiata, and 

 between them and the latter. They vary in size, the largest measuring 

 0'0035mm. ; many are not a third of that size, and they are not disposed 

 in linear fashion, as in Fig. 5, but apparently placed without any 

 orderly arrangement. 



The nucleoli are six in number in the section, and they are very 

 conspicuous. The two larger measure 0*01 68mm. , and the smallest 



