OYSTER CULTURE IN FRANCE. 521 



necessary to do this frequently ; for, independently of the 

 difficulty which there is always in working at that season, 

 the hair-weeds, which are most prejudicial, have disap- 

 peared. 



The young oysters growing in the depots are not sub- 

 jected to any treatment during the six or seven months 

 that they stay there. The depot being situated pretty low 

 in the sea, the water covering them is purer, and algae are 

 scarcer. Nothing more is done than to wash them, on 

 their being put into winter quarters and on bringing them 

 out again. 



I should repeat here an observation made by certain 

 rearers at St. Vaast-de-la-Hougue, that certain parts of the 

 grounds worked became unsuitable for keeping oysters, 

 and seemed exhausted. There are some persons who, to 

 remedy this state of things, have taken the step of giving 

 their pares rest for a year, in order to leave these aquatic 

 fields time to improve, and to some extent to recover. I 

 should add that they have had reason to congratulate them- 

 selves on this resolve. 



It is necessary now to enter into sundry details, to 

 discover the many causes which may have combined to 

 produce this exhaustion. The two principal ones are the 

 following : ist. The overcrowding of too large a number 

 of oysters in the same pare. 2nd. The incessant rising of 

 foetid mud formed by vegetable matters in decomposition, 

 which the water carries in every direction. In the first 

 case the oysters receive but insufficient nourishment ; in- 

 sufficient, because if in a given quantity of water there is 

 only nourishment for 1000 oysters, 50,000 cannot find their 

 food there, and thinness and sickness are the necessary 

 consequences. 



