The Outline of Science 



tors in the land was stored away in the winter of 1904-5 in a paper 

 packet no larger than an envelope." 



Thus from the Wild Wheat of Mount Hermon there evolved 

 one of the most important food-plants of the world. This surely 

 is Evolution going on. 



2 



Changes in the Animal Life of a Country 



Nothing gives us a more convincing impression of evolution 

 in being than a succession of pictures of the animal life of a coun- 

 try in different ages. Dr. James Ritchie, a naturalist of distinc- 

 tion, has written a masterly book, The Influence of Man on 

 Animal Life in Scotland (1920), in which we get this succession 

 of pictures. "Within itself," he says, "a fauna is in a constant 

 state of uneasy restlessness, an assemblage of creatures which in 

 its parts ebbs and flows as one local influence or another plays 

 upon it." There are temporary and local changes, endless dis- 

 turbances and readjustments of the ''balance of nature." One 

 year there is a plague of field-voles, perhaps next year "grouse 

 disease" is rife; in one place there is huge increase of starlings, 

 in another place of rabbits ; here cockchafers are in the ascendant, 

 and there the moles are spoiling the pasture. "But while the parts 

 fluctuate, the fauna as a whole follows a path of its own. As well 

 as internal tides which swing to and fro about an average level, 

 there is a drift which carries the fauna bodily along an 'irretrace- 

 able course.' ' This is partly due to considerable changes of 

 climate, for climate calls the tune to which living creatures dance, 

 but it is also due to new departures among the animals themselves. 

 We need not go back to the extinct animals and lost faunas of past 

 ages for Britain has plenty of relics of these which "illustrate 

 the reality of the faunal drift," but it may be very useful, in illus- 

 tration of evolution in being, to notice what has happened in 

 Scotland since the end of the Great Ice Age. 



Some nine thousand years ago or more, certain long-headed, 



