PROFITABLE CULTIVATION OF THE OYSTER. 879 



tbe protecting walls, and the autumnal gales completed the work of de- 

 struction, so that soon every trace of the basins had disappeared. 



If the open " Watten Sea " is not suitable for the construction of oys- 

 ter-beds, oysters might possibly be cultivated within the dikes which 

 shelter the fertile marshes of the North Sea coasts. For this purpose 

 basins would have to be dug within the dikes and connected with the 

 sea by a canal. Wherever this canal would cut a dike, a sluice would 

 have to be constructed so as to prevent the sea from overflowing during 

 high floods. The oyster-basins could not be constructed near the exist- 

 ing sluices of our marsh-dikes, because these serve to let the fresh water 

 run off from the marshes ; the oyster-basins would therefore be filled 

 with fresh water instead of salt water. 



Unless oyster-beds could be constructed within a dike, and, without 

 endangering the surrounding country, could be filled with salt water, 

 the oysters would have but a very scanty supply of food, much less at 

 any rate than in the open sea, where, every day, a greater quantity of 

 water containing food runs over every oyster than in a small basin. But 

 the greatest danger for the basin oysters would be frosty weather, be- 

 cause on our coasts the lowest water is during east wind, which, at the 

 same time, brings the greatest cold. At the very time when highVater 

 and frequent change of water would be the best means of protecting 

 the oysters from death by freezing, this means could not be employed, 

 and during cold winters many more oysters would die in the basins than 

 in the natural oyster-beds. 



Oysters raised artificially would, therefore, with us be a very expen- 

 sive luxury ; and probably they would cost us more than they cost some 

 of the English oyster cultivators. According to an oflicial report by 

 Mr. Blake, inspector of fisheries, every oyster raised artificially near 

 Eeculvers, at the mouth of the Thames, cost £50 ; in Heme Bay, £100 ; 

 and in some other places, as much as £500 ! 



All investigations which have been made have led to the deplorable 

 result that a i^rofitable cultivation of the oyster according to the French 

 method is impossible on our North Sea coasts. We are, therefore, con- 

 fined in our activity to the oyster-beds, and we shall have to answer the 

 important question whether it is possible to enlarge the existing oys- 

 ter-beds and to construct new ones. 



Old beds will grow naturally when the movable and clayey bottom 

 near their boundaries becomes firm and pure, which may be occasioned 

 by changes of the direction and force of the currents. In such cases 

 the enlargement of the bed may be accelerated by putting shells on the 

 firm bottom, so as to provide objects to which the young oysters may 

 cling. 



In order to construct new oyster-beds we want more extensive por- 

 tions of the " Watten Sea,^^ with a depth of one to four meters, and not 

 liable to change. At my request the men best acquainted with the 

 bottom of the " Watten >Sm," viz, those men who have to mark the navi- 



