130 



Part III. — Sixteenth Annual Rejxyrt 



vesicle and appeared to be contained within it, but as a space existed 

 near to the margin of the latter it had probably been displaced in cutting. 

 With moderate powers the margin of the yolk-nucleus is ill-defined, 

 appearing to shade off into the clear zone, which is clear because of the 

 absence of the granular protoplasm. Examined with the 2mm. oil 

 immersion, ocular 4, it appears finely granular without definite structure. 



Another feature in these eggs must be referred to. In the fresh con- 

 dition, the germinal vesicle is seen to be more or less surrounded by 

 aggregations of minute oil-globules, which are also scattered throughout 

 the cytoplasm (fig. 10, PI. IT.). These clusters of little oily globules 

 are conspicuous when the egg is examined with a low power (Zeiss A., oc. 

 2), the intervening spaces appearing clear. But when it is examined 

 with -imm. Zeiss apochromatic, oc. 2, the intervals are seen to be crowded 

 with immense numbers of very minute globules, invisible under the lower 

 power. 



The outline of the germinal vesicle in these small fresh eggs is difficult 

 to make out, and appears as a delicate line, while neucleoli could not be 

 detected within it ; thus differing from the ordinary condition seen in the 

 pelagic ovum. In the osmic preparations the oil-globules appear as black 

 opaque dots, or aggregations of dots (showing fusion of the globules as a 

 rule), although they were treated in the ordinary way, and mounted in 

 balsam. In eggs as small as 0'036mm. a few black specks may be 

 observed. In specimens preserved in picro-sulphuric acid, vacuoles — 

 fewer and larger — represent the position of the oil-globules. 



The conditions of the germinal vesicle or cytoplasm above described 

 were also found in sections of the ovary of a specimen 45 inches long, 

 caught on 20th May, preserved in Perennyi's fluid, and stained with 

 saffranin, eosm, and hi^matoxylin ; as well as in sections of the ovary of 

 a fish, 48 inches in length, caught on 9th Febmary, preserved in picro- 

 sulphuric acid, and stained in the same way. This ovary contained 

 yolked eggs, and the smallest eggs present measured about O'OlSmm. 

 The yolk-nucleus is very well shoAvn in the former series (fig. 12, PI. 

 II.), but yolk formation has not begun. 



The only sections I possess showing the presence of yolk in the im- 

 mature eggs are those just referred to, in which it is far advanced ; the 

 smaller eggs, at the base of the pouches, are pale, and more or less 

 vacuolated at the margin. The appearance of the larger yolked eggs is 

 shown in fig. 11, PI. II. It will be observed that the larger 

 spherules are placed towards the periphery, as if the growth of the 

 cytoplasm in the eggs of the angler took place from the germinal vesicle, 

 outwards — compare the eggs of the dory in fig. 11, PI. III. It will also 

 be noticed that the network of vacuolar spaces usually present around the 

 germinal vesicle in eggs possessing an oil- globule is absent in these ; the 

 small oily droplets are probably interspersed throughout the cytoplasm, 

 and collect at maturation. In these mounted sections the granular 

 contents of the yolk-spherules car scarcely be detected, but they are 

 stained intense red. In spirit preparations the spherules appear as an 

 aggregation of solid bodies. 



In the larger yolked eggs the nu ^leoli are very conspicuous and highly 

 stained. They are composed of a large number of smaller spheres, vesicles, 

 or granules. They collect at the centre of the germinal vesicle, and some 

 of them undergo disintegration, while in the clearer central part, within 

 the circle of nucleoli, numerous minute corpuscles or granules become 

 arranged in chains, in the form of loops or coils. The process. 



