INFLUENCE OF CLIMATE, 397 



A momentary g-lance at some of the well established facts illus- 

 trative of the operations of climatic influence in the other kingdoms 

 of nature, will enable us the more clearly to recognize the workings 

 of this influence in the higher realms of human life. 



The influence of climate upon plant and animal life, has long 

 been noticed and carefully studied. The outlines of geology are as 

 familiar to the popular mind as nursery rhymes, and we have long 

 since ceased to wonder that thousands of species of plants and 

 animals should have been swept from the face of the globe in con- 

 sequence of changes in their natural conditions which they were 

 not able to withstand. It was not possible, for instance, for pri- 

 meval vegetation to exist subsequent to tlie coal period, nor could 

 warm blooded animals have lived prior to that time. Whenever a 

 change in the conditions necessary to the life of any species of 

 plants or animals has been so sudden and violent that they could 

 not bring themselves into harmony with the new and discordant 

 elements, it has become extinct. But if the rate of change has 

 been sufficiently gradual to allow the organism to fit itself to its 

 new surroundings, then life has continued, but under a modified 

 type. 



In that far remote time when a uniform tropical climate obtained 

 over all of what was then the western hemisphere — when no 

 change of seasons marked the round of the year — when an unend- 

 ing summer reigned over all — a tropical vegetation flourishpd from 

 the shores of the Mexican gulf to the Arctic ocean. Along the 

 slopes of our New England mountains the palm tree lifted its cor- 

 onet of leaves into a torrid air, and these very hillsides were 

 bedecked with the rich garniture of tropical flowers. The huge 

 mastedon roamed in lordly pride through these valleys, and found 

 a congenial home on what are now the shores of Hudson's bay. 



But at length a change came. By slow and almost impercepti- 

 ble degrees winter commenced its reign at the pole, and the tem- 

 perature went down over all the co*ntinent. In process of time 

 there was, in these northern latitudes, no more life for stately 

 palm or lordly mastedon. In their places, the spruce and the 

 pine put on their robes of living green, and the polar bear came 

 out upon the northern snow. So through these long geologic 

 epochs, one form of life has followed another, as the changes in 

 the surface of our globe have demanded, till nearly five hundred 

 thousand species of animals have become extinct, and of plants 

 not less than fifty thousand. 



