DEVONIAN FISHES OF IOWA 41 



the grand total that has existed since life began.* How now 

 shall science answer the question as to the origin of these my- 

 riads of forms! Evolution answers it in this way: the language 

 in which it is here stated is that of Professor Kellogg (ibid. 

 p. 10) : 



"Now all these millions of kinds of animals and plants can 

 have had an origin in some one of but three ways; they have 

 come into existence spontaneously, they have been specially 

 created by some supernatural power, or they hiive descended 

 one from the other in many -branching series by gradual trans- 

 formation. There is absolutely no scientific evidence for either 

 of the first two ways ; there is much scientific evidence for the last 

 way. There is left for the scientific man, then, solely the last; 

 that is, the method of descent. The theory of descent (with 

 which phrase organic evolution may be practically held as a syn- 

 • onym) is, then, simply the declaration that the various living as 

 well as the now extinct species of organisms are descended from 

 one another and from common ancestors. It is the explanation 

 of the origin of species accepted in the science of biology." 



It is needless to pursue the subject further. Sufficient has 

 been said to convey some notion of the extraordinary impetus 

 given to science and all forms of speculative thought through the 

 medium of a few grand illuminating conceptions, pre-eminent 

 among which is the theory of evolution. Bear in mind that 

 rarely are great truths hit upon offhand, as the result of hazard, 

 by a fortunate guess, or by intuition. Enlightenment, the reward 



*The marvelous properties of radium furnish unexpected aid to the palaeon- 

 tologist by way of granting him a much greater time-estimate than physicists have 

 been willing to allow. Professor Lankester, in his presidential address before the 

 British Association at the York meeting (1906), states the matter in this wise: 



"Even a small quantity of radium diffused through the earth will suffice to keep 

 up its temperature against loss by radiation! If the sun consists of a fraction of one 

 per cent, of radium, this will account for and make good the heat that is annually 

 lost by it. 



"This is a tremendous fact, upsetting all the calculations of physicists as to the 

 duration in past and future of the sun's heat and the temperature of the earth's 

 surface. The geologists and biologists have long contended that some thousand 

 million years must have passed during which the earth's surface has presented 

 approximately the same conditions of temperature as at present, in order to allow 

 time for the evolution of living things and the formation of the aqueous deposits 

 of the earth's crust. The physicists, notably Professor Tait and Lord Kelvin, 

 refused to allow more than ten million years (which they subsequently increased 

 to a hundred million)— basing this estimate on the rate of cooling of a sphere of 

 the size and composition of the earth. They have assumed that its material is self- 

 cooling. But, as Huxley pointed out, mathematics will not give a true result when 

 applied to erroneous data. It has now, within these last five years, become evi- 

 dent that the earth's material is not self-cooling, but on the contrary self-heating. 

 And away go the restrictions imposed by physicists on geological time. They are 

 now willing to give us not merely a thousand million years, but as many more as 

 we want." 



