28 



HA RD WICKE'S SCIENCE-GOSSIF. 



this very point that the most gigantic strides have 

 been made in our knowledge of late years. 



I will quote a few jmssages showing the feelings of 

 Darwin on this subject, and how far he was from 

 making a fixed creed of his own conclusions. 



" In many cases it is most difficult even to 

 conjecture by what transitions organs have arrived at 

 their present state." * 



*' In searching for the gradations through which an 

 organ in any species has been perfected, we ought to 

 look exclusively to its lineal progenitors ; but this is 

 scarcely ever possible." t 



It is hardly necessary to say what brilliant work 

 has elucidated these difficulties of late years. 

 Embryologists have traced the stages through which 

 every part of the future animal passes on its way to 

 its own form of diffeientiation ; as for instance the 

 modifications of the bones in the leg and wing of the 

 chick, in which, at an early period the indications of 

 a former five-toed condition can be seen ; the germs 

 of teeth destined never to cut the gum, and the 

 consolidation of the bones in ruminants and equid^s ; 

 and the three sets of kidneys in vertebrates. 



Palaeontologists have had successes as brilliant ; 

 they can show the phylogeny of an immense number 

 of our present mammals, whilst the embryologists have 

 demonstrated their ontogeny: the "lineal pro- 

 genitors" have been found. Darwin says % , " Two 

 forms can seldom be connected by intermediate 

 varieties, and thus proved to be the same species, 

 until many specimens are collected from many places ; 

 and with fossil species this can rarely be done. We 

 shall perhaps best perceive the improbability of our 

 being able to connect species by numerous fine 

 intermediate fossillinks, by asking ourselves whether, 

 for instance, geologists at some future period will be 

 able to prove that our different breeds of cattle, sheep, 

 horses, and dogs are descended from a single stock or 

 from several aboriginal stocks. . . . This could be 

 effected only by his discovering in a fossil state 

 numerous intermediate gradations ; and such success 

 is improbable in the highest degree." This success, 

 which the great master thought " improbable in the 

 highest degree " has been attained ; and the 

 "numerous, fine, intermediate gradations in the 

 fossil state," have been traced. 



Again, in arguing with writers who assert the im- 

 mutability of species by asserting that geology yields 

 no linking forms, he say5,§ " If we take a genus 

 having a score of species, recent and extinct, and 

 destroy four-fifths of them, no one doubts that the 

 remainder will Stand much more distinct from each 

 other. . . . What geological research has not re- 

 vealed is the former existence of infinitely numerous 

 gradations, as fine as existing varieties, connecting 

 together nearly all existing and extinct species. But 

 this ought not to be expected." So far is the great 



master from hoping, that before one generation hacf 

 grown up since his death, these " infinitely numerous 

 variations, as fine as existing varieties," "connecting 

 existing with extinct species"; "these numerous, 

 fine, intermediate fossil links " would be found in 

 countless numbers, and that the ancestral forms no^. 



" Origin of Species," p. 156. 

 Ibid. p. 279. 



t Ibid. p. 144. 

 j Ibid. p. 280. 



pjg_ y.—a, reproductive cell ; b, nucleus, which after extrusion 

 of the polar globules will form the future animal or plant ; 

 c, " germ-plasm " left over to carry on the qualities of 

 ancestors, and transferred from generation to generation. 

 Whatever changes occur in an animal are due entirely to 

 modifications of the " germ-plasm." 



only of our " different breeds of cattle, sheep, horses 

 and dogs," but those of the bear, the cat, the weasel, 

 the rhinoceros, the camel and of countless other 

 animals would be accurately known. * 



And, with regard to his own special hypothesis of 

 evolution through natural selection, he speaks again 

 and again of our ignorance of the causes which have 

 given rise to those variations upon which natural 

 selection has to work. The battle which Darwin 

 had to fight was to prove the evolution and conse- 

 quent changeability of species, in opposition to 

 opponents who believed in the special creation and 

 unchangeability of species. Having had that great 

 battle won for them, scientific men have had leisure 

 to turn their attention to the cause of the variations 

 controlling evolution. Later in his life, after having 

 borne the burden and heat of the day, Darwin had 

 more leisure to turn his own attention to this most 

 important question. The following extracts will 

 exemplify the earlier and later phases of his opinions 

 on this subject : — " Variations appear to arise from 

 the same unknown causes acting on the cerebraf 

 organization, which induce slight variations or indi- 

 vidual differences in other parts of the body ; and 

 these variations, ozving to our ignorance, are often said 

 to arise spontaneously." f (The italics are mine.) 

 After speaking of the number of facts collected with 

 respect to the transmission of the most trifling, as 

 well as of the most important characters in man, and 

 also in domestic animals, he says : " With regard to 

 the causes of variability, we are in all cases very 

 ignorant." And again, he speaks of the "complex 

 and little-known laws governing the production of 

 varieties," being " the same, so far as we can judge, 

 as the laws which have governed the production of 

 distinct species." J 



* " Origin of the Fittest " (Professor Cope) ; " Les Ancetres 

 de nos Animaux" (Gaudry) ; "The Mammalia" (Oscar 

 Schmidt. 



t "Descent of Man," pp. 38, no, in. 



X "Origin ol Species," p. 415. 



