THE HISTORY OF FISH-CULTURE. 485 



in the Scottish rivers, and represented in the work published under the 

 assumed name of Ephemera.* Such are the principal results to be 

 ascribed to M. Ooste. He has recently collected his memoirs and reports 

 into a volume, under the title of " Practical Instructions upon Piscicul- 

 ture." He sets forth in these instructions the knowledge previously 

 acquired, and those which he has drawn from his personal experience, 

 and he adopts some of the improvements introduced by M. Millet in the 

 practice of the new industry. We regret that the author of this little 

 work, written with much elegance and clearness, has not oftener cited 

 the sources from which his information is taken. 



The same day upon which M. Coste presented his work to the Acad- 

 emy of Sciences, M. de Quatrefages read before this learned body some 

 researches upon the milt of certain fresh- water fish.t The question here 

 treated of is fundamental ; and before it had been resolved, it was impos- 

 sible to use the necessary precision in artificial fecundations. This 

 labor is then of great importance in the double point of view of compar- 

 ative physiology and the application of zoology. We know by the 

 experiments of Prevost, of Geneva, and of M. Dumas, that the milt 

 owes its physiological properties to the presence of animalcules, which 

 move in a manner very peculiar, and that all fecundating-power disap- 

 pears the moment that these animalcules die. Now, M. de Quatrefages 

 shows that the duration of these movements is extremely short in the 

 case of fish, ev^en in the most favorable circumstances. Thus, in the 

 milt of the brochet, diluted with water, all vitality ceases after eight 

 minutes and ten seconds; the animalcules of the mullet are all dead 

 after three minutes aud ten seconds ; and those of the carp after only 

 three minutes. This period of activity is still more limited for the perch 

 and barbel, since it only reaches two minutes forty seconds for the for- 

 mer, and two minutes ten seconds for the latter. Neither is it equal for 

 all the animalcules of the same fish, and half of them perish in much 

 less time. Besides, the preceding figures are taken at the degree of 

 heat most favorable to the duration of these movements, and even slight 

 variations above or below this point destroy them with great rapidity. 

 The temperature which maintains longest the vitality of the animalcules 

 is, for winter-fish like the trout, forty-one to forty-eight degrees of Fah- 

 renheit ; for those of the early spring, fifty to fifty-five degrees ; for those 

 of later spring, as the carp and the perch, sixty-three to sixty-eight ; 

 and for the summer kinds, seventy-seven to eighty-seven. When the 

 temperature somewhat exceeds these limits the increase of energy on 

 the part of the animalcules compensates, to a certain extent, for the 

 shorter duration of their vitality. These results apply to those which 

 are disseminated through the water; when they remain united in small 



* The Book of the Salmon, by Ei)hemera, [E. Fitzgibbon,] assisted by Arthur Young. 

 See also the Agronomic Annals, vol. i, p. 234, 1851. 



t Comptes-renilus of the Academy of Sciences, session of May 30, 1853, vol. xxxvi, 

 p. 936; Annals of the Natural Sciences, third series, vol. xix, p. 341., 1853. 



