110 J. T. CUNNINGHAM. 



less numerous^ and the oil globules in the zone next to the 

 nucleus much smaller and less conspicuous. Fig. 10 repre- 

 sents the stage at which the formation of yolk granules at the 

 periphery is just commencing, small oil globules being visible 

 in the inner zone ; eggs in this stage are comparatively few in 

 number. There are, as in all stages of the ovary, a certain 

 number of yolkless ova. 



Sections from the ovary of a specimen 19| inches long, 

 obtained in Grimsby market on April 24th, show a less 

 advanced condition of maturation. The majority of the ova 

 are in a stage a little earlier than that of fig. 12, the oil 

 vacuoles being smaller and more numerous. 



I have sections from another stage in the history of the 

 turbot^s ovary, the material having been taken from a fish 

 2 feet 1^ inches long, on July 23rd, and preserved in picrosul- 

 phuric acid and spirit at sea immediately after death. The 

 preservation is not quite satisfactory, but the sections show 

 many points worthy of mention. With the exception of a 

 small number in young stages, all the eggs are in two stages, 

 namely, ripe, with the yolk in a continuous mass surrounded 

 by a thin envelope of protoplasm, and nearly ripe, with the 

 yolk spheres still separate. There are scarcely any inter- 

 mediate stages between these two; but in the nearly ripe con- 

 dition the protoplasmic strands separating the yolk globules 

 are not visible toward the centre of the egg. It is evident, 

 therefore, that the fusion of the yolk spherules takes place 

 almost simultaneously. The nearly ripe eggs in these sections 

 are nearly all ruptured on one side, the zona radiata being 

 much thickened on the opposite side, and the contents parti- 

 ally escaping. This may be attributed to the effect of the 

 picro-sulphuric acid, but whether its action has been to contract 

 the zona radiata, or to burst the latter by swelling the yolk, I 

 cannot say. Curiously enough the ripe eggs are not burst, but 

 in them the zona radiata is thinner, and the diameter of the 

 egg larger. It is evident that the yolk swells considerably 

 during the final stage of maturation. 



The sections of the ripe eggs exhibit an internal homo- 



