12 REPORT— 1891. 



scientific opinion ; and still less is there any unanimity in the acceptance 

 of natural selection as the sole or even the main agent of whatever 

 modifications may have led up to the existing forms of life. The deepest 

 obscurity still hangs over the origin of the infinite variety of life. Two 

 of the strongest objections to the Darwinian explanation appear still to 

 retain all their force. 



I think Lord Kelvin was the first to point out that the amount of time 

 required by the advocates of the theory for working out the process they 

 had imagined could not be conceded without assuming the existence of a 

 totally different set of natural laws from those with which we are 

 acquainted. His view was not only based on profound mechanical reason- 

 ing, but it was so plain that any layman could comprehend it. Setting aside 

 arguments deduced from the resistance of the tides, which may be taken to 

 transcend the lay understanding, his argument from the refrigeration of the 

 earth requires little science to apprehend it. Everybody knows that hot 

 things cool, and that according to their substance they take more or less 

 time in cooling. It is evident from the increase of heat as we descend into 

 the earth, that the earth is cooling, and we know by experiment, within cer- 

 tain wide limits, the rate at which its substances, the matters of which it 

 is constituted, are found to cool. It follows that we can approximately 

 calculate how hot it was so many million years ago. But if at any time 

 it was hotter at the surface by -50° F. than it is now, life would then have 

 been impossible upon the planet, and therefore we can without much diffi- 

 culty fix a date before which organic life on earth cannot have existed. 

 Basing himself on these considerations Lord Kelvin limited the period of 

 organic life upon the earth to a hundred million years, and Professor Tait 

 in a still more penurious spirit cut that hundi-ed down to ten. But on the 

 other side of the account stand the claims of the geologists and biologists. 

 They have revelled in the prodigality of the ciphers which they put at the 

 end of the earth's hypothetical life. Long cribbed and cabined within the 

 narrow bounds of the popular chronology, they have exulted wantonly in 

 their new freedom. They have lavished their millions of years with the 

 open hand of a prodigal heir indemnifying liimself by present extravagance 

 for the enforced self-denial of his youth. But it cannot be gainsaid that 

 their theories require at least all this elbowroom. If we think of that 

 vast distance over which Darwin conducts us from the jelly-fish lying on 

 the primeval beach to man as we know him now ; if we reflect that the 

 prodigious change requisite to transform one into the other is made up of 

 a chain of generations, each advancing by a minute variation from the 

 form of its predecessor, and if we further reflect that these successive 

 changes are so minute that in the course of our historical period — say 

 three thousand years — this progressive variation has not advanced by a 

 single step perceptible to our eyes, in respect to man or the animals and 

 plants with which man is familiar, we shall admit that for a chain of 

 change so vast, of which the smallest link is longer than our recorded 

 history, the biologists are making no extravagant claim when they demand 



