66 THE PRESENT. 



fied areas vastly more extended than those that lie patent 

 to geological research. Still, in face of all these obstruc- 

 tions and imperfections, paleontology has wonderfully en- 

 larged our conceptions of vitality, has opened up to the 

 present age a theme altogether unknown to our ancestors, 

 and, guided by a true knowledge of the present, is destined 

 yet to unfold a fuller and fairer vision of the life that has 

 gone before us. As the zoologist pushes his discoveries 

 into space, so the palaeontologist pushes his discoveries into 

 time. As the former turns to unexplored regions in the 

 hope of finding new forms, so the latter turns to unexplored 

 formations formations whose areas are as varied as their 

 dates, and whose strata give promise of other and other 

 life-revelations for centuries yet to come. 



3.-CO-ADAPTATIONS OF FLOKA AND FAUNA. 



Perfect as the existing flora and fauna may appear, each 

 in its own proper line, they are only constituent portions 

 of a greater life-system, bound together by numerous co- 

 adaptations and adjustments. As each is adapted to, as 

 well as dependent on, external conditions, so both are de- 

 pendent on one another, and, as ' presently constituted, 

 neither could possibly enjoy a separate existence. Both, 

 for example, are incessantly dependent on the atmosphere, 

 yet the oxygen which the plant exhales is inhaled by the 

 animal, and the carbonic acid expired by the animal is ab- 

 sorbed and assimilated by the plant. The plant rooted in 

 the soil and casting abroad its leaves and branches in the 

 atmosphere, though seemingly deriving the main elements 

 of its growth from inorganic sources, is nevertheless stimu- 

 lated into life and exuberance by the presence of organic 

 decay ; w r hile the animal, being herbivorous, subsists im- 



