228 



SCIENCE. 



[N. S. Vol. XXII. No. 556. 



tion is often spoken of as almost synony- 

 mous with the evolution of the various spe- 

 cies of animals on the earth, and this again 

 is sometimes thought to be practically the 

 same thing as the theory of natural selec- 

 tion. Of course those who are conversant 

 with the history of scientific ideas are aware 

 that a belief in the gradual and orderly 

 transformation of nature, both animate and 

 inanimate, is of great antiquity. 



We may liken the facts on which theories 

 of evolution are based to a confused heap 

 of beads, from which a keen-sighted 

 searcher after truth picks out and strings 

 together a few which happen to catch his 

 eye, as possessing certain resemblances. 

 Until recently, theories of evolution in both 

 realms of nature were partial and discon- 

 tinuous, and the chains of facts were corre- 

 spondingly short and disconnected. At 

 length the theory of natural selection, by 

 formulating the cause of the divergence of 

 forms in the organic world from the pa- 

 rental stock, furnished the naturalist with 

 a clue by which he examined the disordered 

 mass of facts before him, and he was thus 

 enabled to go far in deducing order where 

 chaos had ruled before, but the problem of 

 reducing the heap to perfect order will 

 probably baffle the ingenuity of the investi- 

 gator forever. 



So illuminating has been this new idea 

 that, as the whole of nature has gradually 

 been reexamined by its aid, thousands of 

 new facts have been brought to light, and 

 have been strung in due order on the neck- 

 lace of knowledge. Indeed, the transfor- 

 mation resulting from the new point of 

 view has been so far-reaching as almost to 

 justify the misapprehension of the unscien- 

 tific as to the date when the doctrines of 

 evolution first originated in the mind of 

 man. 



It is not my object, nor indeed am I 

 competent, to examine the extent to which 



the theory of natural selection has needed 

 modification since it was first formulated 

 by my father and Wallace. But I am 

 surely justified in maintaining that the 

 general principle holds its place firmly as a 

 permanent acqiftsition to modes of thought. 



Evolutionary doctrines concerning in- 

 animate nature, although of much older 

 date than those which concern life, have 

 been profoundly affected by the great im- 

 pulse of which I have spoken. It has thus 

 come about that the origin and history of 

 the chemical elements and of stellar sys- 

 tems now occupy a far larger space in the 

 scientific mind than was formerly the case. 

 The subject which I shall discuss to-night 

 is the extent to which ideas parallel to 

 those which have done so much towards 

 elucidating the problems of life, hold good 

 also in the world of matter; and I believe 

 that it will be possible to show that in this 

 respect there exists a resemblance between 

 the two realms of nature, which is not 

 merely fanciful. It is proper to add that 

 as long ago as 1873 Baron Karl du Prel 

 discussed the same subject from a similar 

 point of view, in a book entitled 'The 

 Struggle for Life in the Heavens.'^ 



Although inanimate matter moves under 

 the action of forces which are incompar- 

 ably simpler than those governing living 

 beings, yet the problems of the physicist 

 and the astronomer are scarcely less com- 

 plex than those which present themselves 

 to the biologist. The mystery of life re- 

 mains as impenetrable as ever, and in his 

 evolutionary speculations the biologist does 

 not attempt to explain life itself, but, 

 adopting as his unit the animal as a whole, 

 discusses its relationships to other animals 

 and to the surrounding conditions. The 

 physicist, on the other hand, is irresistibly 

 impelled to form theories as to the intimate 



^ Der Kampf urn's Dasein am Himniel (zweite 

 Auflage), Denicke, Berlin, 1876. 



