THE SEASON OF THE YEAR. 241 



seasons and the climate in each particular country depend in part 

 upon many minor contributory causes. It is not merely nearness 

 to or distance from the equator that counts; we have to consider 

 also relative distribution of land and water, elevation, prevalent winds, 

 exposure, condensation, and many other elements of a complex prob- 

 lem. In Ecuador, for example, whose very name means the equator, 

 the plain is always in scorching summer, the mountains are always in 

 perpetual spring. The monsoons, again, produce in other countries 

 some curious results: they depend themselves on the change of rela- 

 tive temperature in sea and land at different seasons; and they break 

 upon the Himalayas with this odd and unexpected effect, that the 

 snow line on the southern side of that vast range goes very far down, 

 owing to the immense rainfall (or rather snowfall) and the conse- 

 quent spread of snow fields and glaciers; while on the northern side 

 it descends but a very little way, owing to the extreme desert drought 

 and the great summer heat of the central Asiatic table-land. We 

 have thus the apparent paradox that millions of Tibetans occupy 

 towns and cultivate farms to the north at a height from three to four 

 thousand feet above the snow line on the southern slope of the same 

 mountains. 



Looking at the matter broadly, then, and taking for granted the 

 now generally accepted modern view that the great oceans and great 

 continents have been relatively fixed (though liable to minor fluctua- 

 tions and variations of outline) throughout all geological time, and 

 that the earth's crust has not shifted from pole to equator or vice 

 versa, we arrive at last at the following probable conclusions: There 

 have always been seasons more or less marked, and these have been 

 more or less organically answered by corresponding changes or cycles 

 of change in plants and animals. Rain and drought have in many 

 cases more to do with such changes than variations of temperature. 

 The seasons, again, are less marked in the tropics than in temperate 

 and circumpolar climates. Nevertheless, even near the equator, they 

 exert and have always exerted certain organic influences — have re- 

 sulted in annual cycles in the life of species. Even before the coming 

 on of the Glacial epoch, the seasons were probably somewhat more 

 marked in the temperate and polar regions than in the tropics, the 

 longer day in summer and the greater directness of impact of the 

 rays making the summer months always warmer. But for various 

 reasons, among which we may presumably rank the absence in early 

 ages of high land at the poles and of an accumulated polar ice cap, 

 together with the existence of warm sea currents from the tropics 

 to the poles, the winters of preglacial ages seem to have been rela- 

 tively mild, perhaps (if we may judge by the types of plant life) 

 milder than those of South Carolina and Georgia in our own period. 



VOL. LIV. — 18 



