174 CIRCUMSTANCES FAVOURING 



greater will be the retardation ; in this respect, 

 analogous to what occurs in vegetable life, in 

 the case of germinating seeds. 



AMICUS. You say nothing of gravel for a bed 

 or of the exclusion of light, the one and the 

 other, noticeable, I think you have said, in the 

 natural process. 



PISCATOR. They may be useful though not 

 essential in that process ; remember I am 

 speaking of the artificial, and of the easiest 

 mode, and most inviting way of conducting it. 

 Try it, and be assured you will find it answer, 

 and in the curious phenomena of young life and 

 development it will exhibit, especially if you 

 call in the aid of the microscope, it will most 

 amply repay the little care and attention it may 

 require. 



AMICUS. Of what use is the gravel in the 

 natural process, if not required in the artificial ? 



PISCATOB. I believe it has a double use or 

 more, first, that of covering and protecting 

 the ova during the foetal development; and 

 next, after their hatching, that of affording 

 hiding places for the young fish, and the means 

 of keeping themselves free of impurities by the 

 friction which can hardlv be avoided whilst 



