CONSERVATION OF DEEP SEA BEDS. 1037 



It has been said that alterations of temperature have 

 not any great effect on the inhabitants of the bottom of the 

 sea, owing to the supposition that no great amount of cold 

 can possibly be experienced there, sea-water being at its 

 greatest density at about 40 Fahrenheit. 



Here, however, theory and practice do not agree. Mr. 

 Policy, a dredgerman of forty-two years' experience, when 

 examined before the 1876 Commission, said that " he knew 

 a nice bed of scallops which existed a year or two pre- 

 viously, to the westward of the Straits of Dover, and which 

 showed at once, when the fishermen drifted on to them, 

 that they were to the westward of the oyster grounds. One 

 spring, after a severe winter, he was dredging on this bed, 

 and he found that all the scallops had been killed by the 

 cold. The same spring he found all the spider-crabs near 

 Jersey to have been destroyed from the same cause, so that, 

 whereas in former years they had no difficulty in getting 

 a large basketful in a day, that year they could not find 



one.' 



This shows how the bottom of the sea can be affected 

 by temperature ; other dredgermen and deep-sea fishermen 

 express similar opinions confirming this view. 



They say also that cold breaks up the ground below 

 the water, and renders everything there brittle in the same 

 way, though perhaps to a less degree, than it does above 

 water. 



DEPTH AND DENSITY. 



In the inter-tidal zone, when high water occurs about 

 noon during the spatting season, the action of the sun is 

 greatest, and development of life most active, about high- 

 water mark. (Professor Sullivan.) 



It is the reverse of this in the zone below low-water 

 mark. When low-water spring-tides occur in the middle 



