I020 BULLETIN OF THE BUREAU OF FISHERIES. 



retained in the hatching boxes and fed until they are ready to be transferred 

 into the rearing ponds. 



The shortcomings of the rectangular type of hatching and rearing box have, 

 I regret to say, occupied more space than I originally intended to devote to 

 them. I am, however, assured that the interest and importance of the subject 

 to pisciculturists will be its own apology, if an apology be needed, for the tax I 

 have been compelled to impose on your patience and good nature before dealing 

 with the principles in construction which should be observed in making a hatching 

 and rearing box which will combine thorough efficiency with effective sanitation. 

 These are three in number and are as follows: (i) The material of which the 

 box is constructed must not only be impervious to water, but must have a 

 smooth, hard surface which will act as a preventive against the lodgment of the 

 spores of fungus ; (2) the box must be shaped so that the water is kept in constant 

 circulation so long as the supply is running; (3) the outlet must be placed at a 

 point which will enable it to maintain a direct current over the eggs during their 

 period of incubation and at the same time, when the fry have to be fed, act 

 automatically to remove any small particles of unconsumed food. 



As regards material, I have met with nothing equal to highly glazed earth- 

 enware, and were I in a position which would enable me to indulge in the luxury 

 of an experimental hatchery the whole of its equipment would be of china or 

 delft. These materials are, however, too fragile for the requirements of a 

 hatchery in which from 150,000 to 250,000 eggs are laid down each season, and 

 consequently we shall have to cast about for a material which will make an 

 effective substitute. Thin enameled iron, such as is used in the manufacture 

 of basins, pie dishes, and other domestic utensils, will answer the purpose 

 admirably. To me personally it is a matter of surprise that it has not already 

 been generally adopted for piscicultural work in preference to wood, seeing that 

 of the two materials it is, size for size, relatively the lighter. Moreover, it has 

 the additional advantage of being cheaper, is easier to keep clean, and possesses 

 far greater durability. 



Coming to the second principle of construction, I have endeavored to show 

 that any approach to the conditions under which eggs are incubated in a natural 

 state is not attainable with a rectangular hatching box. It will, therefore, be 

 necessary to abolish straight lines in favor of curves, as indicated in the accom- 

 panying sketches. Perhaps, however, you may grasp my meaning more readily 

 if, in imagination, you take a length of piping of fairly large dimensions and 

 divide it lengthways into equal halves. At each end of one of these halves 

 affix a circular head and you will then have an exact representation of the type 

 of box I am endeavoring to describe, but as yet minus the outlet. This consists 

 of a circular opening of at least 3 inches in diameter, cut at one end of the box. 



