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ossesses many useless organs and that many of its relations to the external world are capable of considerable improvement。
In writing this essay I have purposely refrained from taking a definite position with regard to the problems touched。 My desire has been to write a chapter showing the influence of Darwin's work so far as Embryology is concerned； and the various points which come up for consideration in discussing his views。 Darwin was the last man who would have claimed finality for any of his doctrines； but he might fairly have claimed to have set going a process of intellectual fermentation which is still very far from completion。
XI。 THE PALAEONTOLOGICAL RECORD。
I。 ANIMALS。
By W。B。 SCOTT。 Professor of Geology in the University of Princeton； U。S。A。
To no branch of science did the publication of 〃The Origin of Species〃 prove to be a more vivifying and transforming influence than to Palaeontology。 This science had suffered； and to some extent； still suffers from its rather anomalous position between geology and biology； each of which makes claim to its territory； and it was held in strict bondage to the Linnean and Cuvierian dogma that species were immutable entities。 There is； however； reason to maintain that this strict bondage to a dogma now abandoned； was not without its good side； and served the purpose of keeping the infant science in leading…strings until it was able to walk alone； and preventing a flood of premature generalisations and speculations。
As Zittel has said： 〃Two directions were from the first apparent in palaeontological researcha stratigraphical and a biological。 Stratigraphers wished from palaeontology mainly confirmation regarding the true order or relative age of zones of rock…deposits in the field。 Biologists had； theoretically at least； the more genuine interest in fossil organisms as individual forms of life。〃 （Zittel； 〃History of Geology and Palaeontology〃； page 363； London； 1901。） The geological or stratigraphical direction of the science was given by the work of William Smith； 〃the father of historical geology；〃 in the closing decade of the eighteenth century。 Smith was the first to make a systematic use of fossils in determining the order of succession of the rocks which make up the accessible crust of the earth； and this use has continued； without essential change； to the present day。 It is true that the theory of evolution has greatly modified our conceptions concerning the introduction of new species and the manner in which palaeontological data are to be interpreted in terms of stratigraphy； but； broadly speaking； the method remains fundamentally the same as that introduced by Smith。
The biological direction of palaeontology was due to Cuvier and his associates； who first showed that fossils were not merely varieties of existing organisms； but belonged to extinct species and genera； an altogether revolutionary conception； which startled the scientific world。 Cuvier made careful studies； especially of fossil vertebrates； from the standpoint of zoology and was thus the founder of palaeontology as a biological science。 His great work on 〃Ossements Fossiles〃 （Paris； 1821） has never been surpassed as a masterpiece of the comparative method of anatomical investigation； and has furnished to the palaeontologist the indispensable implements of research。
On the other hand； Cuvier's theoretical views regarding the history of the earth and its successive faunas and floras are such as no one believes to… day。 He held that the earth had been repeatedly devastated by great cataclysms； which destroyed every living thing； necessitating an entirely new creation； thus regarding the geological periods as sharply demarcated and strictly contemporaneous for the whole earth； and each species of animal and plant as confined to a single period。 Cuvier's immense authority and his commanding personality dominated scientific thought for more than a generation and marked out the line which the development of palaeontology was to follow。 The work was enthusiastically taken up by many very able men in the various European countries and in the United States； but； controlled as it was by the belief in the fixity of species； it remained almost entirely descriptive and consisted in the description and classification of the different groups of fossil organisms。 As already intimated； this narrowness of view had its compensations； for it deferred generalisations until some adequate foundations for these had been laid。
Dominant as it was； Cuvier's authority was slowly undermined by the progress of knowledge and the way was prepared for the introduction of more rational conceptions。 The theory of 〃Catastrophism〃 was attacked by several geologists； most effectively by Sir Charles Lyell； who greatly amplified the principles enunciated by Hutton and Playfair in the preceding century； and inaugurated a new era in geology。 Lyell's uniformitarian views of the earth's history and of the agencies which had wrought its changes； had undoubted effect in educating men's minds for the acceptance of essentially similar views regarding the organic world。 In palaeontology too the doctrine of the immutability of species； though vehemently maintained and reasserted； was gradually weakening。 In reviewing long series of fossils； relations were observed which pointed to genetic connections and yet were interpreted as purely ideal。 Agassiz； for example； who never accepted the evolutionary theory； drew attention to facts which could be satisfactorily interpreted only in terms of that theory。 Among the fossils he indicated 〃progressive；〃 〃synthetic；〃 〃prophetic；〃 and 〃embryonic〃 types； and pointed out the parallelism which obtains between the geological succession of ancient animals and the ontogenetic development of recent forms。 In Darwin's words： 〃This view accords admirably well with our theory。〃 （〃Origin of Species〃 （6th edition）； page 310。） Of similar import were Owen's views on 〃generalised types〃 and 〃archetypes。〃
The appearance of 〃The Origin of Species〃 in 1859 revolutionised all the biological sciences。 From the very nature of the case； Darwin was compelled to give careful consideration to the palaeontological evidence； indeed； it was the palaeontology and modern distribution of animals in South America which first led him to reflect upon the great problem。 In his own words： 〃I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos； secondly； by the manner in which closely allied animals replace one another in proceeding southward over the Continent； and thirdly； by the South American character of most of the productions of the Galapagos archipelago； and more especially by the manner in which they differ slightly on each island of the group。〃 （〃Life and Letters of Charles Darwin〃； I。 page 82。） In the famous tenth and eleventh chapters of the 〃Origin〃； the palaeontological evidence is examined at length and the imperfection of the geological record is strongly emphasised。 The conclusion is reached； that； in view of this extreme imperfection； palaeontology could not reasonably be expected to yield complete and convincing proof of the evolutionary theory。 〃I look at the geological record as a history of the world imperfectly kept； and written in a changing dialect； of this history we possess the last volume alone； relating only to two or three countries。 Of this volume； only here and there a short chapter has been preserved； and of each page； only here and there a few lines。〃 （〃Origin of Species〃； page 289。） Yet； aside from these inevitable difficulties； he concludes； that 〃the other great leading facts in palaeontology agree admirably with the theory of descent with modification through variation and natural selection。〃 （Ibid。 page 313。）
Darwin's theory gave an entirely new significance and importance to palaeontology。 Cuvier's conception of the science had been a limited； though a lofty one。 〃How glorious it would be if we could arrange the organised products of the universe in their chronological order！。。。The chronological succession of organised forms； the exact determination of those types which appeared first； the simultaneous origin of certain species and their gradual decay； would perhaps teach us as much about the mysteries of organisation as we can possibly learn through experiments with living organisms。〃 （Zittel op。 cit。 page 140。） This； however； was rather the expression of a hope for the distant future than an account of what was attainable； and in practice the science remained almost purely descriptive； until Darwin gave it a new standpoint； new problems and an altogether fresh interest and charm。 The revolution thus accomplished is comparable only to that produced by the Copernican astronomy。
From the first it was obvious that one of the most searching tests of the evolutionary theory would be given by the advance of palaeontological discovery。 However imperfect the geological record might be； its ascertained facts would necessarily be consistent； under any reasonable interpretation； with the demands of a true theory； otherwise the theory would eventually be overwhelme