SELECTION: ORGANIC AND SOCIAL 191 



is the selectionist interpretation of this charac- 

 teristic ? The first step is to recognise that animals 

 are very variable as regards colouring, and thus 

 there is raw material to work on. Furthermore, a 

 variation in the direction of whiteness is common 

 white blackbirds and swallows, white rats and 

 moles, being well known. It seems likely that a 

 ferment essential to the manufacture of the pig- 

 ment drops out of the inheritance of these 

 albinos. The change is of germinal origin, and 

 it is hereditary. Now there is a keen struggle 

 for existence in Arctic regions, and any character 

 that gives its possessor a pull is likely to have 

 selective value. But there are various advan- 

 tages in a white dress in snowy regions it is 

 the least conspicuous and the most comfortable. 

 Those who turn white will get on best, other things 

 being equal. Therefore we have white races in 

 Arctic regions, and we may corroborate the 

 argument by referring to a simple experiment. 

 Prof. Davenport had 300 chickens in a field, 80 

 per cent, white or black and conspicuous, 20 per 

 cent, spotted and inconspicuous. In a short time 

 twenty-four were killed by crows, but only one 

 of the killed was spotted. 



In a heavy snowstorm at Johannesburg in 

 August 1909, many hundreds of trees were destroyed 

 by the weight of snow on the branches. It was 

 interesting, after the storm, to notice that the 

 elimination was in a marked degree discriminate. 

 The trees that suffered most were the imported 

 Australian trees, such as Blue Gums and Black 

 Wattles, quickly growing, with soft wood, and 

 with abundant foliage that caught the snow. On 

 the other hand, the deodars from the Himalaya 



