864 



BULLETIN OF THE BUREAU OF FISHERIES. 



first stage shall have been passed that it will be legitimate to inquire whether 

 the results obtained in the laboratory may or may not be repeated on a larger 

 scale, i. e., to practical purpose, with perhaps a somewhat different technique. 

 Practical marine pisciculture, the origin of which does not date further back 

 than twelve years, is as yet in its scientific period. 



The two principal difficulties involved in the solution of the scientific problem 

 are the following: (i) The obtaining in captivity of natural and normal hatches 

 in as great numbers as might be desired, and the determination of the conditions 

 of these hatches. (2) The feeding and the preservation of a reasonable number 



of larvae beyond the crit- 



M 



ical period and under con- 

 ditions such that the ex- 

 periment may be repeated. 

 As has been justly ob- 

 served by Messrs. Fabre- 

 Domergue and Bietrix 

 (op. cit.), the incubation, 

 hatching, and preserva- 

 tion of the larvae until the 

 beginning of the critical 

 period do not present any 

 difficulties. 



In the laboratories of 

 pisciculture in America, 

 Norway, and England the 



Fig. I. — Early development of the turbot. I, Fecundated egg; li, egg with 

 blastoderm; iii, egg with embryo, not pigmented, iv. egg with pigmented 

 embryo, v. larva just after hatching; vr, larva with vitei us about half 

 resorbed ; vii. larva with vitellus almost entirely resorbed: viil. larva in 

 critical period, vitellus just resorbed; ix. larva at end of critical period, o. 

 Oil globule; 6. blastoderm ; e. embryo; tj, vitellus; 6. mouth; a, anus; o.eye; 

 p, axis of insertion of pectoral fin. 



question of hatching in 

 captivity has been solved 

 for the plaice and for the 

 cod, but could not be 

 solved for the turbot, the 

 only marine fish truly interesting from the point of industrial breeding. The 

 passage through the critical period had not been attempted for any species in 

 laboratories here cited, because the fishes were deposited in the sea before the 

 beginning of this period. The principal object of practical marine pisciculture in 

 recent years, then, in Europe at least, has been to obtain normal hatches of 

 turbots in captivity and to carry their larvae past the critical period. 



It was at the laboratory of St. Vaast-la-Hougue that numerous normal 

 hatches of turbots were obtained for the first time by A. E. Malard in 1898.° 



o Malard, A. E. : Sur le developpement et la pisciculture du turbot. 

 des Sciences, Paris, 17 juillet, i8gg. 



Comptes rendus de 1' Academic 



