BIOLOGICAL PALAEONTOLOGY 113 



headway against their Reptilian relatives. Unless 

 patience prompted by some peculiar intelligence is to 

 be attributed to early Mammalia, !there must surely be 

 assumed tendencies akin to precocity and backwardness 

 in homogenetic groups. Just as precocity usually belies 

 its early promise (however noteworthy premature progress 

 may be), so backwardness is not infrequently followed 

 by later acquirements that may lose nothing in brilliance 

 because of their slow attainment. 



Since the early phases of racial evolution are so 

 imperfectly known in most Invertebrate phyla, the 

 established case of the Mammalia may serve as an 

 indication of the existence of the principle of " deferred 

 specialization " ; evidence of comparable qualities in 

 Invertebrate phylogeny may be sought with confidence. 



(V) THE LIFE-CURVE 



Although the student of Nature may well stand aghast 

 at the immensity and complexity of the problems and 

 materials that lie before him, he finds, on closer inspec- 

 tion, that fundamental simplicity underlies the whole. 

 After generations of study, resulting in a welter of 

 observed facts and a chaos of abandoned hypotheses, a 

 seer arises to show the single law whereby apparent 

 confusion is resolved into an ordered scheme. In the 

 physical sciences, phenomena are, for the most part, 

 capable of reference to relatively few basic rules with 

 almost mathematical precision ; the results of experiment 

 can in many cases be confidently foretold. In the various 

 branches of Biology, something of the confusion that 

 obscured the physical world before the advent of Newton 

 still lingers. The principle of Evolution, like all broad 

 conceptions, has served to co-ordinate, and so render 

 intelligible, many of the manifestations of life, while the 

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