GLOSSARY 245 



geneously (in solution). When the subdivision of a 

 suspended substance is so minute as to make its reten- 

 tion by filter paper impossible, the solution is known 

 as a colloidal solution. 



Continental Edge. — ^The junction between the conti- 

 nental shelf and the continental slope, usually found 

 at a depth of about 100 fathoms and indicated by a 

 change of gradient. 



Continental Shelf. — ^That part of the ocean-floor lying 

 between the shore-line and the 100-fathoms line ; 

 the gradient is usually very gentle, with higher portions 

 called coast-banks. 



Continental Slope. — ^That part of the ocean-floor lying 

 between the 100-fathoms line and the mean sphere level 

 (1700 fathoms); the gradient of the bottom is usually 

 much steeper than in shallower and deeper water. 



Deeps. — ^Those parts of the ocean in which depths greater 

 than 3000 fathoms have been recorded. 



Density. — ^The density or specific gravity of sea-water 

 is the ratio of a certain volume of salt water to that 

 of an equal volume of fresh water at 39.2° F. The 

 temperature at which the density is measured must 

 be stated, as the densities of liquids vary greatly with 

 temperatm^e. Since the density of sea-water depends 

 only on temperature and salinity, if the density ia 

 always measured at the same standard temperature, 

 or corrected to it, the differences of density are due 

 to differences of salinity alone. 



Enzymes. — Substances eminently characteristic of living 

 matter ; they are catalytic agents, as a rule soluble 

 in water, in salt solution, or in glycerine, and are 

 effective only in one reaction. They cause the 

 formation of anti-enzymes in animal blood. They 

 are colloidal in nature, and are unable to resist 

 boiling temperatures. 



Geospheres. — The globe may be regarded as being made 

 up of concentric spheres, the atmosphere, the hydro- 



