64 THE NEW ART OF BREEDING FISH. 



development. Another and more serious inconveni- 

 ence often results : if one of the eggs becomes spoil- 

 ed and covered with byssus, this byssus spreads to 

 the adjoining eggs, and in a few days reaches all that 

 are contiguous and destroys them. The only mode 

 to diminish the extent or arrest the progress of this 

 evil, when the eggs have not been heaped up, is to 

 remove, at once, from the hatching place all that 

 show the least trace of alteration. If in place of 

 sacrificing, an attempt is made to save them by free- 

 ing tbem, with the aid of a brush, from the vegeta- 

 ble parasites covering them, not only wiU it be a use- 

 less trouble, since the tainted eggs are already struck 

 with death, but the evil will be aggravated by 

 spreading over the healthy eggs the particles of de- 

 structive byssus, by the very operation of cleansing. 



There are cases where the employment of the 

 brush becomes indispensable and efi6.cacious : as when 

 sediment forms in a thick layer on the eggs, whose 

 presence hinders the development of the embryo. It 

 is necessary, then, to remove such matter by passing 

 lightly over them a fine brush of badger hair, such 

 as painters use. {PI. \,fig. 7.) 



Lastly, the intervention of man becomes neces- 

 sary when the laiTse of insects, abundant in certain 

 waters, attack the eggs : from these enemies he must 

 deliver them. 



