CULTIVATION OF THE TURBOT. 869 



however, one would always have the resource of small plankton organisms in 

 the pools left when the sea recedes. Moreover, the continuous agitation appa- 

 ratus will allow us to keep alive a small reserve of plankton to supply the needs 

 of our larvae for three to four days. And, lastly, one more argument, shall it 

 be considered a priori impossible to breed certain plankton organisms, carefully 

 selected? Continuous agitation apparatus would undoubtedly be suitable for 

 this purpose likewise. The experiments of Bracque have almost solved this 

 question already. I am not opposed a priori to a semiartificial food as, for 

 example, the Monas dunali of marshes successfully employed by Messrs. Fabre- 

 Domergue and Bietrix for feeding their larvse of soles, and it is even possible 

 that this organism might be made to render the greatest service in marine pisci- 

 culture. But it is nevertheless most true that it is in the great variety of 

 plankton organisms that we shall find the food necessary for the normal feeding 

 of the larvse of teleosts with pelagic eggs. I dared not experiment with purely 

 artificial food, advised by others (cheese, shrimp meal, etc.). I believe that 

 rapid putrefaction would occur. I believe, in short, that during the first period 

 the best food would be small plankton organisms, carefully selected. 



Let us add that in hatching troughs the temperature of the water ought 

 not to be above 20° C. We have operated constantly at a temperature of from 

 18° to 20° C. It seemed best to have it from 15° to 20° C. Let us say, further, 

 that during the critical period we lost only i individual in 10, a result which 

 might be considered excellent, it seems to me. 



What is left to be done in the culture of the turbot? There remains to 

 protect the young larvae from the end of the critical period to the end of the 

 metamorphosis, since we are sure, and we have often shown by experiment, that 

 there is nothing easier than to fatten young turbots and other pleuronectids, 

 and make them grow. For this purpose it will be sufficient to substitute for 

 the plankton, as rapidly as possible, fish flesh mashed into a pulp, this to be 

 consecutively replaced by larger and larger pieces of fish as the size of the 

 turbots increases. 



It remains likewise to carry marine pisciculture from the domain of science 

 to industry, and this is not the least of the work to be done — to determine, in 

 fact, whether the procedure applicable on a small scale in laboratories may be 

 carried on on a larger scale. It is necessary to determine the price of the food 

 required to fatten the fishes bred and to see if this price allows a profit, taking 

 into consideration the market price per kilogram of the turbot. 



It is possible that the waste of fishes in the vicinity of great harbors might 

 constitute a valuable resource for industrial marine pisciculture of the future. 



