118 The Development Theory; A Review. 



beings has revealed a multitude of facts which have been 

 generalized by Haeckel into the law, that " the history of the 

 development of the individual portrays the history of the develop- 

 ment of its tribe." Thus, then among the successive changes of 

 the egg from its first formation to the exclusion or birth of the 

 animal, we may read with our own eyes a concise summary of 

 its development through a long series of ancestors, whose remains 

 are entombed in the rocks or destroyed for ever by geologic 

 catastrophes. Embryology thus enables us to read in miniature 

 and close at hand, an epitome of the greater record which the 

 lapse of time has removed almost beyond our ken, and its accidents 

 have in great part effaced. 



Confirmatory of the testimony of embryology is that of geology, 

 which forms the subject of the next chapter. These two 

 records confirm and supplement each other. It is not probable 

 that the former can ever supply all the details of the past history 

 of any species. It is certain that from the record of the latter 

 many chapters are missing, and will never perhaps be recovered. 

 But geology is supplying ample evidence that the deductions of 

 embryology are well founded, and embryology is furnishing 

 unmistakable indications of the line which descent has followed 

 in the production of existing species. Both records are as yet 

 very incomplete, and call for years of patient labor and thought 

 to lessen their imperfection. But every advance in the same 

 direction, every new fact points the same way. " Missing links" 

 come to light connecting species with species in the past, and 

 every one adds vastly to the force of the cumulative argument. 

 With the discovery of every one, the gaps remaining become less 

 important, and before long the induction may become sufficient 

 to warrant the acceptance of a universal inference by every 

 unbiassed mind. 



i4 Wherever the known incompleteness of the geological 

 record, ' prevents our explaining ' a difficulty, it becomes the 

 believer in the development theory frankly to acknowledge 

 that the riddle is too intricate to be solved by any means at his 

 command. And yet, until an evolutionary rise of species had 

 been assigned as an explanation of the succession of higher and 

 higher animals and plants through the geologic ages, what 

 adequate reason for this progress could be given ? Strike out 



