1038 OYSTERS, AND ALL ABOUT THEM. 



of the day, as is the case on the coast of France between 

 Cape La Hogue and Cape Frehel, and around the Channel 

 Islands, the spat of those oysters that are laid in the shallow 

 water outside of low-water mark have the best chance of 

 existence, as the warmer the water, up to certain limits, the 

 greater the activity of the very young oysters in moving, 

 feeding, and growing. The rise and fall of the tide is 

 also of importance ; in the above-named localities there 

 is a rise and fall of over forty feet. The alternation of 

 comparatively deep and very shallow water exposes the 

 oysters to successive alternations of temperature and to 

 the effects of the variation in the amount of gases in the 

 water, which are by no means favourable to successful 

 reproduction. 



Although oyster culturists differ on the subject, we 

 think it has been proved by actual experiment that the spat 

 when first emitted in the black-sick stage is of less specific 

 gravity than the water surrounding the parent oyster, and 

 that it rises towards the surface for a time, (i) How long 

 this condition lasts has not yet been satisfactorily deter- 



* 



mined ; it may be only a few hours, but it is possible that 

 several days elapse before it descends in a sticking humour. 

 If it has been drifted into very deep water, the pressure will 

 have a retarding influence on the development of the germs 

 as they descend, and at a certain depth, which as yet is 

 unknown, the spat is destroyed. 



Again, as it appears probable that both young oysters 

 and spat have a better chance of living under conditions 

 of pressure which are natural to them than under new con- 



(/) One oyster cultunst says that "last year he never saw so much 

 spat floating, yet not one did he breed." Another says : " Yes, that's 

 true ; but the year before last they had just as much floating, yet they 

 had a capital fall of spat." 



