A Mountain Tulip. 183 



strays from the fauna and flora of all neighbouring 

 continents. But as \vc have already seen in the con- 

 verse case of the hairy spurge, it would be incredible 

 that such an accident should have occurred over and 

 over again in a hundred separate cases, so that every 

 suitable place in the whole northern hemisphere 

 should separately, by mere luck, have received a 

 distinct colony of appropriate cold-climate plants. 

 Incredible, I should say, even if the instance of the 

 Lloydia stood alone without any analogues ; but in 

 fact, as I shall try to point out by-and-by, it is only 

 one instance out of a thousand that might be quoted ; 

 for every Arctic land and every snow-clad Alpine peak 

 is covered close up to the limit of vegetation with 

 dozens or hundreds of similar plants, insects, and 

 animals, which arc nowhere found in all the inter- 

 vening temperate or lowland regions. Clearly all 

 these coincidences cannot be due to mere accident ; 

 we must seek for their reason in some single and 

 common fact. 



See this great rounded block of smooth granite 

 on whose solid shoulders I am now sitting ; how 

 wonderfully grooved and polished it is, with long, 

 deep, rounded furrows running lengthwise across its 

 face in the same direction as the general dip of the 

 Conway valley. What can have made those curious 



