322 THE FLOUNDER FAMILY. 



the reasons for the limitation of the size of this sex and the 

 small size of the male organs. 



Most of the females were very ripe, and the slightest pressure 

 caused the escape of a considerable quantity of ova, which fell in 

 a mass into the water, and then slowly mixed with it. In the 

 experiments made in the laboratory, the smallest trace of milt 

 fertilized every egg in the vessels, which were about a foot across, 

 so that the activity of the sperms was characteristic. The quan- 

 tity of ripe ova discharged at a given time was quite as large in 

 proportion as in the plaice, in the turbot, and in the flounder. 

 Fishes in which the testes are small, as in the torsk, plaice, long 

 rough dab, and sole, do not appear to differ much in regard 

 to the rapidity of issue of the ripe eggs from those with large 

 testes. The small size of the testes in the horse, compared 

 with their large size in the porpoise, is another instance of 

 the caution requisite in drawing conclusions on this head. At 

 any rate, in regard to the fishes, the ascertained facts up to 

 date do not seem to warrant strong statements on the subject. 

 The ripe female sole in Scottish waters discharges a considerable 

 number of eggs, and the same applies to the ripe lemon-dab. 

 The quantity of ripe eggs which issues from a torsk is about as 

 large in proportion as in a cod, yet the testes of the two differ 

 much in size. 



The egg of the long-rough dab, on issuing from the oviduct, 

 is beautifully translucent (PI. Ill, fig. 19), and measures from 

 1-0668 mm. to 1-1430 mm. The capsule (zona radiatci) clings 

 somewhat closely to the contained yolk, and is wrinkled all 

 over quite as much as in the lemon-dab. The perivitelline 

 space is small, and thus differs from the condition as ordinarily 

 seen in the tow-nets. As a rule, the yolk or egg-proper has 

 a diameter of T066S mm., while the capsule has a diameter of 

 1-1430 mm. When placed in sea- water, and whether fertilized 

 or not, a gradual change takes place in the perivitelline space, 

 so that next morning that is, in 12 hours, the diameter of the 

 capsule is from T7907 to T8669 mm. probably by the imbibition 

 of water, as in the case of desiccated eggs, while the diameter 

 of the egg-proper in the centre remains nearly the same (PL III, 

 fig. 20). This distention removes many of the wrinkles from 



