134 THE NEW AKT OF BEEEDINO FISH. 



is dug sufficiently capacious for a first deposition of 

 ova. Then the female enters this first hollowed link 

 of the bed, and deposits therein a portion of her ova. 

 That done, she retires down stream, and the male 

 instantly takes her place, and, pouring, by emission, 

 a certain quantity of milt over the deposited ova, 

 impregnates them. After this the fish commence a 

 second excavation, immediately above the first, and 

 in a straight line with it. In making the excava- 

 tions they relieve one another. When one fish grows 

 tired of its work it drops down stream until it is re- 

 freshed, and then, with renovated powers, resumes 

 its labors, relieving at the same time its partner. 

 The partner acts in the same spirit, and so their la- 

 bor progresses by alternate exertion. The second 

 bed completed, the female enters it as she did the 

 first, again depositing a portion of ova, and drops a 

 little down stream. The male forthwith enters the 

 excavation, and impregnates the ova in it. The 

 different nests are not made on the same day, but on 

 different days, progressively. It is never so all at 

 once. The ova in the first nest are covered with 

 gravel and sand, dug from the second, being carried 

 into it chiefiy by the action of the current. The 

 excavating process just described is day by day con- 

 tinued, until the female has no more ova to- deposit. 

 The last deposition of ova is covered in by the action 

 of the fish and water, breaking down some of the 

 gravel crust above and over the nest. Thus is form- 

 ed a complete spawning bed — ^not at once, not by a 



