146 J. T. CUNNINGHAM. 



the egg of the turbot, all from one series of sections, the 

 material for which was fixed some hours after the death of 

 the fish in picro-sulphuric acid. Tiie chromatic fibrils in 

 these sections are very indistinct, in many of the oldest ova 

 they are not to be distingaished, the structure appearing 

 uniformly granular. In the younger ova, and in some of the 

 older, however, distinct traces of the fibrils are to be seen. 

 The sections from which figs. 28 and 29, PI. 4, are taken were 

 prepared from material taken from a fish just captured and 

 fixed immediately ; but the mixture used, picro-sulphuric acid 

 and spirit, has not given very good results. The fibrils are 

 very indistinct. 



It will be seen that in the turbot ovum in the stage shown 

 in fig. 12, when the whole of the cytoplasm is filled with yolk 

 globules, the nucleoli are very large and deeply stained ; in 

 many cases each consists of a number of large coarse gran- 

 ules. In the ovary to which figs. 28 and 29 refer, the ova are 

 nearly all in two stages, the ripe stage in which the yolk glo- 

 bules have fused together, and the nearly ripe stage in which 

 the yolk is a little more dense than in fig. 12. In the former 

 stage I have not been able to detect the germinal vesicle, or 

 any remnant of it at all. In the latter stage the vitelline 

 membrane has burst at one point, in consequence of the action 

 of the fixing reagent, which has caused the yolk to swell, but 

 the germinal vesicle is not much distorted. In fig. 28 it will 

 be seen that the nucleoli are distributed irregularly about the 

 nuclear cavity, with the exception of the centre, where there 

 are one or two indications of fibrils. The nucleoli are more 

 numerous than at the preceding stage, having presumably 

 subdivided. In some of the eggs, although these are not 

 quite the largest, the germinal vesicle presents the remarkable 

 structure shown in fig. 29. There is a ring of stained bodies 

 having the form of rods of various shapes, and within the 

 ring are faint indications of fibrils. The stained rods must 

 obviously be the transformed nucleoli, and at the same time 

 they possess considerable resemblance to chromosomes. Ac- 

 cording to Riickert the nucleoli vanish altogether, and are not 



