486 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



masses they die much more slowly. The peculiarities of the milt may 

 thus be preserved for a much louger time when it is not diluted, and 

 especially when it is kept at a very low temperature. It may even be 

 frozen without causing in all cases the death of the animalcules. "M. 

 Millet, who has aided me in all these researches," says M. de Quatre- 

 fages, "has thought of putting the milt with ice into a tin box, so that 

 the water may run out as the ice melts, and then to arrange this box in 

 a second wooden one, pierced with very small holes, and itself filled 

 "with ice." Thanks to these precautions, the learned academician has 

 been able to preserve the milt in a serviceable condition during sixty- 

 four hours. It is worthy of remark that the fecundating-property dis- 

 appears first in that part of the male organ where the liquid is most 

 completely elaborated, and endures some time longer in the deeper parts. 



These facts taken together will explain most of the failures resulting 

 from operations apparently well conducted. They show that the manip- 

 ulations must be accomplished with great quickness, and careful atten- 

 tion must be paid to the temperature of the water. We may conclude 

 from them also that the season of spawning in certain localities must 

 vary in accordance with the atmospheric phenomena; that the short 

 vitality of the milt is one of the causes which oppose the crossing o* 

 the different species in nature ; and that the hitherto unexplained instinct 

 which leads the trout and salmon to mount to the sources of water- 

 courses is owing to the need felt by these animals of finding a degree 

 of temperature suitable to the fecundation and development of their 

 eggs. M. de Quatrefages has also deduced from his researches data of 

 great value for i)ractice, and eminently suited to regulating the methods 

 of artificial fecundation.* The results contaiued in the memoir of M. de 

 Quatrefages give to these methods a scientiflc regularity, which they 

 have wanted hitherto, and tend to endow pisciculture with fixed and 

 precise rules. 



To complete the summary picture of the progress which pisciculture 

 has made from antiquity to our time, and to show its present condition, 

 it remains to point out the numerous and important improvements which 

 are owing to M. Millet, inspector of waters and forests.t 



* Since the male liquid, completely elaborated, loses first its fecundatiug-properties, 

 only that should be used in doubtful cases which is pressed from the milt itself. The 

 vitality of the animalcules not being destroyed by cold iu the male organ, the frozen 

 milt is not to be rejected as useless. If the fecundation cannot be made till after the 

 death of the animal, it is well to take out the milt and preserve it in a wet cloth. In 

 view of the extreme shortness of life of the animalcules, and of the obstacles which 

 the swelling of the envelope may oppose to fecundation, it is useful in the case of cer- 

 tain species to pour the eggs and the male product simultaneously into the same vessel, 

 and thus to render the contact iustantaneous. Of course, the water must never be 

 first impregnated with the milt. 



t Report to the director-general of waters and forests upon the repopulating of the 

 navigable and floating water-courses, by M. de Saint Ouen, administrator of the forests, 

 March, 1853. Annals of the Forests, pp. 272 and 429, July and August, 1853. Inde- 

 j)endently of the various memoirs upon pisciculture which we have hitherto cited, it 



