542 Transactions of the Canadian Institute. [Vol. VIL 



determined by heredity, but the relations of these elements in living 

 matter itself are due to quite different forces in which heredity is a small 

 factor or no factor at all. The acceptance or rejection of either 

 hypothesis depends on the evidence which we can bring as to the 

 composition of the ocean in the very earliest geological periods. 



The conclusions which we can formulate on this point depend on 

 what we accept as the composition of the original crust of the lithosphere, 

 and in our knowledge of the character and composition of the sedi- 

 mentary rocks, and they must also be based on the changes which are 

 admitted to have taken place in the composition of the ocean during all 

 the periods. These conclusions I propose to deal with here in a general 

 way only, for a full consideration of all the facts which have a bearing 

 on them would demand a detailed treatment which would far exceed 

 the limits set for this paper. 



IV. — The Composition of the Primeval Ocean. 



The original condition of the earth was a molten mass in which 

 the temperature was so high that many of the elements now in the rock 

 crust were in a gaseous condition, and dissociated, just as they are at 

 present, in the solar atmosphere. As the dissipation of heat went on 

 some of these must have condensed at degrees of temperature which 

 approximated their present respective volatilization points, while the 

 remainder, oxygen, hydrogen, chlorine, sulphur and carbon would 

 combine to form water, hydrochloric, sulphuric and carbonic acids. 

 The elements, sodium, potassium, calcium, magnesium, and aluminum 

 would also before condensation take out of the original atmosphere 

 chlorine, sulphuric acid, oxygen, and perhaps, carbonic acid, to form 

 the chlorides, sulphates, oxides, and carbonates of these elements, but 

 whether these compounds obtained after condensation depended on 

 whether the temperature of the heated rock surface was still as high as 

 their respective dissociation points. When the molten magma had 

 cooled down to a degree below the lowest dissociation point, all the 

 compounds referred to would be either deposited on the hot rock 

 surface or in the form of vapour in the then atmosphere. When the 

 temperature of the latter had fallen to about lOOO^C, all these com- 

 pounds were removed by condensation, for although, under the atmos- 

 pheric pressure which now obtains, the temperature of condensation is 

 for nearly all these compounds about 200° lower, the very great atmos- 

 pheric pressure of the pre-oceanic period must have rendered the 



