316 WHAT OP THE FUTURE? 



erned, external conditions are undoubtedly one of its prin- 

 cipal factors ; and thus, with other distributions of sea 

 and land, we may anticipate not only other distributions, 

 but other and newer phases of their flora and fauna. 



But, fourthly, if we are to be guided in our speculations 

 respecting the future by our knowledge of the past, another 

 and more important element comes to be considered, and 

 that is, the continuous ascent from lower to higher life- 

 forms which is traceable throughout the whole of the geo- 

 logical periods. If there has been such an ascent through- 

 out the past by some process of development, or whatever 

 it may be, the reasonable presumption is, that the same 

 process will continue to manifest itself in the future. It is 

 by no means asserted that investigators have anything like 

 completed the geological record; but all that has been done, 

 whether in Europe, Asia, America, or Australia, tends to 

 the establishment of an ascent in the main from the cryp- 

 togam to the phanerogam, from the invertebrate to the ver- 

 tebrate ; from the endogen to the exogen, from the fish to 

 the reptile, from the reptile to the bird, and from the bird 

 to the mammal. Even within these great sections there 

 has been a corresponding ordinal advance j and although 

 new discoveries occasionally compel us to modify our views 

 as to the time when certain orders and genera made their 

 first appearance, still no discovery has ever been made that 

 militates in the least against the general doctrine, that the 

 more lowly organised have regularly preceded the higher 

 and more specialised orders. We say " regularly preceded," 

 for though systematists are occasionally puzzled with appar- 

 ent breaks in the continuity, these breaks are either the 

 result of local obliterations, or they arise from limited and 

 imperfect observation. Such having been the progressive 

 evolution of life during the long and physically-varying 



