OVARY AND INTRA-OVARIAN EGG IN TELEOSTEANS. 299 



ova, and affected according as the principal ova are ripe or 

 unripe, it will be convenient to consider the ova first. 



The Ova. — General. 



All writers on the intra-ovarian condition observe large and 

 small eggs in ovaries of fishes which are in any way approaching 

 ripeness. 



Scharff (2) treats in one chapter on the small ova, in another on 

 the large. 



My observations incline me to consider that three conditions 

 must be noticed for fishes, as has been done in the case of 

 batrachians, since it seems more than probable that, in all ripening- 

 ovaries, ova for three consecutive spawning pei'iods are present. I 

 therefore propose to treat of the ova under the names of great, 

 small, and minute. 



The condition is very well seen in sections from the unripe 

 ovary of a haddock, where the small ova are about the size of 

 the nuclei of the great, and the minute are gathered together in 

 clusters, and are individually by no means so large as the nuclei of 

 the small ova. 



So far as I can ascertain, the organ in its flaccid or spent condition 

 has not been previously investigated. Very considerable difficulty 

 has been experienced in obtaining good preservations of spent 

 ovaries, the semi-fluid contents and general disintegration of parts 

 rendering very great care necessary. By removing the organ in 

 situ into the fixing reagents it has, however, been possible to obtain 

 sections showing what I believe to be accurate representations of 

 the organ in this condition. 



Scharff, in his paper already referred to (2), described the 

 smallest ova in the haddock [Gadus seglijinus), and what he terms the 

 next stage in the gurnard {Trigla gurnardus). These two stages, 

 so far as I can determine, are not stages in the development of 

 one season^s eggs, but represent ova which will be extruded at 

 two distinct spawning periods. The larger eggs of his second 

 stage represent, in fact, the formation of great ova at the comple- 

 tion of a spawning season. 



The material collected for his excellent paper was preserved in 

 the summer, the only time when this condition can be seen. 



I am also led to this conclusion by his description of the eggs 

 themselves. 



They show a circular division of the protoplasm into two dis- 

 tinct zones, the inner of the two surrounding the nucleus being 

 more granular, and in section much more darkly stained than the 

 outer ; while the nucleus has its membrane, chromatic substance. 



