Intense cold has checked both native and Russian development over that major portion of Siberia lying north of the mean annual isotherm of degree C.( 32 degrees F.); and it has had a like effect in the corresponding part of Canada.

(Compare maps pages 8 and 9.) It allows these sub-arctic lands scant resources and a population of less than two to the square mile.

Even with the intrusion of white colonial peoples, it perpetuates the savage economy of the native hunting tribes, and makes the fur trader their modern exploiter, whether he be the Cossack tribute-gatherer of the lower Lena River, or the factor of the Hudson Bay Company.

The assimilation tends to be ethnic as well as economic, because the severity of the climate excludes the white woman.

The debilitating effects of heat and humidity, aided by tropical diseases, soon reduce intruding peoples to the dead level of economic inefficiency characteristic of the native races.