Alfred Russel Wallace 



which the geologists have most acquaintance, was probably 

 often as great or greater. Now w^e know that there have 

 been many complete changes of species, new sets of organ- 

 isms have many times been introduced in place of old ones 

 which have become extinct, so that the total amount which 

 have existed on the earth from the earliest geological period 

 must have borne about the same proportion to those now 

 living as the whole human race who have lived and died 

 upon the earth to the population at the present time. . , . 

 Records of vast geological periods are entirely buried beneath 

 the ocean . . . beyond our reach. Most of the gaps in the 

 geological series may thus be filled up, and vast numbers 

 of unknown and unimaginable animals which might help to 

 elucidate the aflfinities of the numerous isolated groups which 

 are a perpetual puzzle to the zoologist may be buried there, 

 till future revolutions may raise them in turn above the 

 water, to afford materials for the study of whatever race of 

 intelligent beings may then have succeeded us. These con- 

 siderations must lead us to the conclusion that our know- 

 ledge of the whole series of the former inhabitants of the 

 earth is necessarily most imperfect and fragmentary — as 

 much as our knowledge of the present organic world would 

 be, were w^e forced to make our collections and observations 

 only in spots equally limited in area and in number with 

 those actually laid open for the collection of fossils. . . . 

 The hypothesis of Prof. Forbes is essentially one that 

 assumes to a great extent the completeness of our know- 

 ledge of the lohole series of organic beings which have 

 existed on earth. . . . The hypothesis put forward in this 

 paper depends in no degree upon the completeness of our 

 knowledge of the former condition of the organic w^orld, 

 but takes what facts we have as fragments of a vast 

 whole, and deduces from them something of the nature 

 and proportion of that whole which we can never know 

 in detail. . . . 



Another important series of facts, quite in accordance 

 with, and even necessary deductions from, the law now 

 developed, are those of rudimentary organs. That these 

 really do exist, and in most cases have no special function 



100 



