OYSTER CULTURE IN HOLLAND. 707 



2nd. No possibility of spat being introduced from outside, 

 which would interfere with the reliability of eventual 

 results. 



To make a comparative experiment with different 

 methods of aerating the sea-water, we have divided the 

 space here indicated in two halves. In the anterior portion 

 a revolving axis with blades attached to it causes a con- 

 tinual current, and at the same time introduces a certain 

 amount of air. In the posterior portion compressed air is 

 introduced into the water by a very large number of small 

 orifices through which it is continually pumped, and from 

 whence the air-bubbles must ascend towards the surface. 



In this way we hope to provide our young oyster larvae 

 with a fair supply of oxygen, to the absence of which we 

 ascribe the failure of previous experiments. Nobody can, 

 of course, predict as to whether we shall be more success- 

 ful, and whether in the breeding season we shall find the 

 different sorts of collecting apparatus we are going to 

 experiment with profusely covered with spat ; but still it 

 was our conviction that we ought to give the question a 

 fair trial, the more so since the experiments of Bouchon- 

 Brandely on the French coast have put it beyond doubt 

 that with the Portuguese oyster (Ostrea angulataj, artificial 

 fecundation and collection of the spat in myriads is quite 

 feasible. The market value of the Portuguese oyster is, 

 however, very low ; the oyster has quite a different shape 

 from ours, and is generally considered of a very inferior 

 flavour. 



This example, though encouraging, does not, however, 

 admit of the conclusion that we have equal chances of suc- 

 cess with Ostrea edulis, our north-European oyster. Part 

 of the development of the young of the latter species takes 

 place within the shell ; and as this is not the case with the 



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