70 



While claiming, then, for geographical conditions 

 an important share in the modification of vitality, it must 

 ever be borne in mind that they are merely co-factors, 

 and could not of themselves account either for the 

 ordinal ascent of life-forms in time, or for the corre- 

 spondence between this ascent in time and the rank 

 that prevails among existing orders. There must be 

 other factors at work, and a higher law governing 

 the, direction of these modifications ; and certain 

 theorists only weaken the argument of external in- 

 fluences by seeking to ascribe to them too much ui 

 the way of varietal and specific deductions. Geogra- 

 phical surroundings have clearly a direct and powerful 

 influence in the modiflcation of hfe — vegetable or 

 animal — and on man as well as on other creatures ; 

 and this, in viewing the relations of nation to nation, 

 and race to race, is all we contend for. 



Our second proposition, therefore, is, that as among 

 the lower animals, so with man, geographical condi- 

 tions are important factors in producing varietal dis- 

 tinctions, and that while adaptive modification may 

 produce forms for certain ends, so may new forms be 

 co-ordinately modified hy the operation of external or 

 physical surroundings. The granting of either or of 

 both of these as sufiicient causes of change, establishes 

 a method in nature which human reason can examine 



