426 G. R. Wieland — Polar Climate in Time. 



north polar area had been at times in tlie past occupied by a 

 continental mass with a but little broken shore line, the general 

 statement that during periods of high eccentricity, this region 

 underwent relativel}^ more change in the distribution of sea- 

 sonal heat and moisture than the inter-polar portions of the 

 globe, could scarcely be challenged. But there is every reason 

 to believe that the presence of numerous peninsulas and archi- 

 pelagoes has long characterized the Atretic regions, and that 

 these added very directly to the peculiarities and Ticissitudes 

 of northern climate, more especiallj^, too, because of a doubt- 

 less not infrequent diversion, as chang^e went on, of ocean 

 currents. At times of high eccentricity there must have been 

 within the limits of the time of the precession of the equinoxes, 

 the most extraordinary changes and diversities in cloudiness, 

 rainfall, dryness, heat and frostiness in the localities about the 

 pole. As in the case of light these changes must have affected 

 the economy of plants and animals profoundly. The possible 

 difference of 36 solar days in the length of the seasons would 

 in many cases produce totally different weather conditions dur- 

 ing the periods of reproduction, sometimes favorable, some- 

 times adverse. Extermination must have been not infrequent, 

 and likewise favorable turns of seasons. But it is scarcely 

 necessary to go into these particular features of polar climate 

 at great length now. This general statement may here suffice 

 as the effect of varying conditions of light, heat and moisture 

 on the lesser scale to be seen in temperate and tropic regions, 

 and therefore their general significance must be fairly well 

 understood. Aside from these factors it only need be remarked 

 that there remain the more conjectural, magnetic, electrical 

 .and perhaps other effects included within the idea of climate 

 as the resultant or manner of the terrestrial reception of radiant 

 energy. 



Perhaps the most fundamental corollary to the view of 

 northern origins as now dealt with at some length, is that of a 

 rapid origin of new species or even genera of both animals 

 and plants. But the idea that this has been the general rule 

 has been suggested, or even insisted upon b}^ various natural- 

 ists. And this rapid origin is especially noteworthy in the 

 vertebrata. The hqrse, I am told by an eminent authority, 

 accomplished more evolution during the deposition of some 

 900 feet of John Day and White Biver Oligocene and Miocene 

 sediments, than in ail of previous Tertiary time as represented 

 by far more than a mile of sediments. The same is in fact 

 known to be true of so many vertebrate stocks that it may well 

 be the rule. More recently Cumings in his able study of the 

 Morphogenesis of Platystroj)hia'^ has also found in the case 

 * This Journal, vol. xv, 1-48, 121-136, 1903. 



