Salmon into Tas^nania, 387 



14. The grand obstacle to the introduction of Salmon 

 spawn hitherto having been the difficulty^ or rather imprac- 

 ticability, of retarding the process of maturation in the 

 ova, so as to prevent hatching out the young fry during 

 the voyage, the Sub-Committee consider that the experi- 

 ment made with spawn would still be almost certainly 

 frustrated, unless means were devised for preserving the 

 ova comparatively cool during the whole, or nearly the 

 whole, of the passage out. Ice, as suggested at page 231 

 of Vol. ii. of Papers and Proceedings of the Royal Society, 

 presents itself as a most convenient and manageable agent 

 for the purpose. The ova of Salmon have, under favourable 

 circumstances, been hatched in fifty days, while cases have, 

 on the ether hand, occurred in which the young fry did 

 not emerge till 140 days had elapsed from the date of 

 fecundation. In the course of experiments at Barnhill, 

 near Perth, spring-water directed so as to flow over boxes 

 of Salmon spawn was found to answer perfectly the purpose 

 of the continuous stream known to be essential for pre- 

 serving vitality in the ova, and so treated, the fecundated 

 spawn yielded young fry in sixty days. In France the 

 Salmon ova are said to be hatched in the artificial breeding 

 ponds in sixty days. At Stormontfield, the site of the 

 piscicultural operations of the proprietors of the Tay fisheries, 

 the time for maturation of the ova and hatching out of 

 the Salmon fry is 120 to 140 days. The temperature of 

 the spring-water referred to would, probably, be a few 

 degrees under the mean annual temperature of the place, 

 which is about 47*5, say 42°, while the temperature of the 

 water employed by the Perth authorities, which was taken 

 from Stormontfield mill-race, would probably range about 

 4° or 5° lower, the atmospheric temperature for the winter 

 quarter there being 3 8' 8°. Organic development in the 

 ova is, therefore, hastened or retarded just in proportion as 

 the temperature may be high or low. M. Coste hatched 

 Salmon ova arranged with layers of gravel, &c. in the 

 usual way in canals or drawer -like compartments placed 

 successively one over another from bottom to top of a tub, 

 into the uppermost of which, a run of fresh water being intro- 



