132 TRANSACTIONS LIVEKPOOL BIOLOGICAL SOCIETY. 



which appears to be the subject of some obscure degenerative 

 process. In its external appearance the ovary presented no 

 very remarkable features : it was about the normal size and 

 weight, and its shape was also very much what one usually 

 finds. On cutting through it Mr. Bailey found, however, that 

 the central part of the roe was occupied by a homogeneous 

 irregularly shaped mass, having the consistency of cheese. He 

 preserved the organ in 5% formalin and sent it to me, but it 

 had been in the preservative for a month or two before I had 

 an opportunity of making a minute examination of it. 



Fig. I, PI. Ill, is reproduced from a drawing of a longitu- 

 dinal section of the ovary. The figure is reduced, and the 

 section was made some distance to one side of the middle line 

 of the organ, so that it does not represent the full size of a 

 median section. The peripheral parts of the ovary are per- 

 fectly normal, the serous coats are present and also the germinal 

 epithelium, and some of the coarser folds, or septa, of the latter 

 are represented. The ova are present in this peripheral part 

 just as they are in the normal ovary. The fish was taken in 

 March, at the time of year (for the north-west coast of England) 

 when many cod are just maturing before spawning begins. At 

 this time the ovaries of the fish are firm and opaque in colour, 

 the serous coats are relatively thick, the eggs are small and 

 opaque, and they are still adherent to the septa of germinal 

 epithelium which traverse the internal parts of the ovary. 

 With maturation the whole organ swells because of the imbibi- 

 tion of water by the ova, and the serous coats and germinal 

 epithelium become thin and almost transparent. The ova 

 swell up and also become transparent, and they become 

 loose from each other and the germinal epithelium, so that 

 when the roe is cut into, the eggs " run," that is, because of 

 their freedom from each other, and their almost perfect trans- 

 parency, the contents of the ovary appear to be liquid. In a 

 cod, or other gadoid fish, most of the ova mature at about the 



