208 



Louis Agassiz. 



investigations of these remains, in which even the 

 texture of the hair, the skin, and flesh has been sub- 

 jected by him to microscopic examination as accurate 

 as if made upon any Hving animal. 



^*We have as yet no clue to the source of this 

 great and sudden change of climate. Various sug- 

 gestions have been made, — among others, that 

 formerly the inclination of the earth's axis was 

 greater, or that a submersion of the continents 

 under water might have produced a decided increase 

 of cold ; but none of these explanations are satisfac- 

 tory, and science has yet to find any cause which 

 accounts for all the phenomena connected with it. 

 It seems, however, unquestionable that since the 

 opening of the Tertiary age a cosmic summer and 

 winter have succeeded each other, during which a 

 Tropical heat and an Arctic cold have alternately 

 prevailed over a great portion of the present Tem- 

 perate Zone. 



At great heights there is never dampness enough 

 to allow the fine snow-crystals to coalesce and form 

 what are called ' snow-flakes.' I have even stood on 

 the summit of the Jungfrau when a frozen cloud 

 filled the air with ice-needles, while I could see the 

 same cloud pouring down sheets of rain upon Lau- 

 terbrunnen below. I remember this spectacle as one 

 of the most impressive I have witnessed in my long 

 experience of Alpine scenery. The air immediately 

 about me seemed filled with rainbow-dust, for the 

 ice-needles glittered with a thousand hues under the 

 decomposition of light upon them, while the dark 

 storm in the valley below offered a strange contrast 



