OYSTERS AND METHODS OF OYSTER-CULTURE. 329 



however, by some loss in simplicity of construction and operation of 

 the apparatus and at the expense of the escape of some of the embryos. 

 Plate III shows the original plans modified by the addition of sluice- 

 gates. 



It is thought that this method of utilizing cultch may solve the 

 problem of the culture of the eastern oyster upon the Pacific coast. 

 Two chief difficulties there interfere with the obtaining- of a strong set: 

 the temperature of the water is in most places too low to insure active 

 spawning, and, secondly, the young of the imported species is crowded 

 out by the rank growth of the native oyster. It is probable that both 

 of these difficulties might be overcome by the use of Dr. Ryder's method 

 or some modification thereof. There is little doubt but that the ebb 

 and flow of the tides through the channels could be so regulated that 

 a sufficient quantity of water would remain at low tide to temper that 

 which would flow in at flood tide. The shallowness of the pond should 

 render it so susceptible to the effect of the sun's rays that a tem- 

 perature several degrees higher than that of the neighboring water 

 could be maintained, and in some places these two or three degrees 

 are perhaps the measure between success and failure in obtaining a set 

 of spat. 



The eastern oyster spawns at 67° or 68° F., but does better at 70°. 

 Ponds such as that described might be located in connection with the 

 sloughs communicating wifh the bays, and, as Mr. C. H. Townsend 

 says that the native Pacific coast oyster does not flourish in such 

 places, the imported species would doubtless have a better opportunity 

 of survival during its early career, the period when it is especially 

 liable to sufitbcation by foreign organisms. If necessary, a filter, such 

 as is described on pp. 330-332 of this paper, might be introduced into 

 the mouth of the canal. This would to some extent interfere with 

 the ebb and flow of the tides between the pond and the slough or bay, 

 but it might be the very thing necessary to retard the interchange 

 sufficiently to allow the water in the pond to become warmed by the 

 sun. 



The experiment is at least worthy of a trial, and it may be the means 

 of saving to the planters of the Pacific coast the large sums of money 

 which are now annually expended in transporting seed oysters across the 

 continent. The experimenter, if successful, would reap the benefit of 

 his own success. The brood oysters used in stocking the pond should 

 preferably be i)lants of several years' standing, as such would be more 

 likely to be acclimated than those brought from the East but a short 

 time prior to the experiment. 



