436 J. BARBELL INFLUENCE OF CLIMATES ON VERTEBRATES 



Yet man, while appreciating these apparent imperfections in evolution, 

 should rejoice that the earth has had such a fortunate planetary history, 

 and that the choices made hy remote ancestral forms in response to the 

 pressure of new, and to them adverse, physical conditions, were not at 

 any time disastrous in their limitations or did not lead to a too long 

 deferment of the attainment of intellectuality — the rarest fruit of time. 



