THE STUDY OF BIOLOGY. 33 



that man's development proceeds along the same lines as those of all 

 other vertebrate animals ; if he knows that man, like the fish, has 

 gill-clefts in his neck in early life, which clefts are of no use whatever 

 to their possessor ; if he finds that other structures, found permanently 

 in lower animals, have a temporary existence in human development 

 is he not morally bound to believe that, human development being a 

 moving panorama of lower forms of life, man himself has had his 

 beginning in some pre-existing and lower form ? If he finds that it 

 is impossible in early life to distinguish the human embryo from that 

 of other quadrupeds, is he not logically bound to regard such likeness 

 as a proof of man's lowly origin ? Such are the queries which the 

 biologist of to-day is forced to face. And when the facts of develop- 

 ment are fairly stated, the answer is not for a moment doubtful, if 

 only from the overwhelming conviction that Nature has written her 

 method and way of creation in our evolution, and that it is, or 

 should be, our highest pride and glory to read aright that " strange 

 eventful history." 



No less powerfully are the deductions and studies of the modern 

 biologist aided by such considerations as those which deal with 

 variation in species as a great fact of life. Formerly, when the fixity 

 of species was deemed a grand fact of biology, the idea that variation 

 might exist was unwillingly entertained, if allowed to have any weight 

 at all. Now, with exact' knowledge that variation exists to a greater 

 or less extent in every living species that change is the law, and 

 fixity in species the exception we can clearly discern Nature's 

 purport in inaugurating such change, as the preliminary to the 

 formation of new races and species. We know that variation pro- 

 ceeds apace in the existing world of life. We ourselves evolve at 

 large, new " races " of cattle and sheep, of pigeons and dogs and 

 horses ; and even if it be fully and freely admitted that the causes of 

 variation are still obscure, there will be found no competent biologist 

 to deny either the reality of the changes in species now proceeding 

 in the world, or the results such changes have wrought in the past. 



Subsidiary methods and aids in studying the biology of to-day 

 exist in such subjects as rudimentary organs, homologies, missing 

 links, and the like. If we discover that a whalebone whale, which 

 has no teeth in the adult state, develops, before birth, teeth which 

 never cut the gum and are gradually absorbed, we must either 

 assume that Nature is woefully improvident in developing useless 

 structures, or that these useless teeth have a meaning. If we find 

 that, whilst a horse walks upon the single toe of each foot, it 

 possesses other two rudimentary and useless toes in its "splint 

 bones," the same idea of meaning or no-meaning comes vividly 

 before our minds. Rudimentary organs teach us, like development, 

 valuable lessons concerning the past history of the race which 



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