ANIMAL LIFE. 499 



HIGHWAYS AND BYWAYS OF ANIMAL LIFE. 



By Professou HERBERT OSBORN, V 



OHIO STATE UNIVERSITY. %.«■• 



"^^r matter what particular theory he may hold as to the origin and 

 -^^ distribution of life over this globe of ours, the thoughtful nat- 

 uralist or the thoughtful student in any sphere of research, if he stops 

 to question at all, must ponder with deepest interest the problems con- 

 nected with the wide dispersal of animal life and its adaptations to 

 most diverse conditions. From darkest depths of abyssal ocean to 

 lofty mountain peak, life abounds and even the high regions of ether- 

 eal air are traversed by one or another of the organisms which repre- 

 sent the great aggregate of animal life. 



It is true that these limits, viewed from a certain standpoint, are 

 very narrow, for a moment's consideration will reveal the fact that life 

 on this sphere now, as in all time past, is confined to a comparatively 

 thin stratum at its surface. From the deepest habitable reaches of 

 ocean to the highest point attainable by bird (a few miles, indeed, of 

 vertical elevation) is a slight range in the radius of the earth, and the 

 densely populated stratum of land and sea — the stratum actually capa- 

 ble of supporting life continuously is, in reality, limited to a very few 

 feet — an exceedingly thin layer on a gigantic ball. One almost trem- 

 bles at the thought of how narrow the habitable limits and how slight 

 a change in conditions of atmospheric or other physical environment 

 might extinguish the vital spark which has characterized mother earth 

 through untold stretches of years. Consider a moment how little below 

 the surface any animal can live, how slightly above it is existence pos- 

 sible. 



But my purpose here is to touch upon some of the routes of devel- 

 opment of the shifting forms of animal life which have drifted hither 

 and thither over sea and land in the great struggle for perpetuity and 

 expansion. 



This effort we can clearly see in the movement taking place under 

 our own eyes, and, more largely, within historic times, as evidenced 

 by the host of animals introduced and spread in the new world from 

 the old, the displacement or extinction of certain forms and perhaps 

 most emphatically in man himself, the dominant animal of the pres- 

 ent age, whose struggle has now become not so much a struggle with 

 other species as a struggle for dominance of race over race, or nation 



