ECOLOGICAL 209 



often a conspicuous creature when the abdomen swells from half an 

 inch to four inches, the dilatation being partly due to myriads of 

 eggs and partly to the abundant nourishment which the workers 

 provide. She sometimes lays 30,000 eggs in a day and ten million 

 in a year; and this may go on for ten years. It is therefore very 

 important for household comfort to find the queen — one of the most 

 prolific mothers in the world. 



The Australian Bushmen make temporary ovens of the big termi- 

 taries, and may even eat some of the salivated clay; the Hillmen of 

 India eat the termites themselves — the queen being regarded as 

 a special delicacy; the pulverised earth of the mounds is often 

 used as a basis for tennis courts and the like. So on and on the 

 Unkages run. 



OTHER INSTANCES OF INTER-RELATIONS 



Inter-relations of the Bracken. — A clear instance of a still 

 unconquered enemy may be found in the bracken — a very serious 

 enemy, though it adds so much beauty to mountains and moor- 

 land in Britain. This common fern is so vigorous in its growth 

 that it smothers, and thus kills out, the grass and other pasture- 

 plants on which the hill-sheep depend. Every year it seems to be 

 steadily reducing the pasturage on hill farms. And besides destroying 

 the pasture, it is harmful in other ways. Thus in a recent study Mr. 

 G. F. Scott EUiot points out that sheep, especially tups, forcing 

 their way through the bracken, get cuts on their forehead below 

 the horns, and that flesh-flies attack the wounds. The parasitised 

 sheep may lie hidden by the tall bracken until it dies. The sheep- 

 tick, Ixodes ricinus, believed to be the carrier of the disease 

 called "trembling", often finds shelter in the bracken, and the 

 same holds for a fly that troubles cattle and horses, Hippohosca 

 equina, whose pupae are found in the humus at the base of the 

 bracken-shoots. 



Reduction of Natural Shelter and its Influence on Wild 

 Fauna. — Gilbert White, who published his evergreen Natural 

 History of Selhorne in 1789, at the time of the French Revolution, 

 was like Darwin in his appreciation of the linkages or inter-relations 

 between living creatures, and in his vivid sense of the cumulative 

 importance of minutiae. Both of these quahties are well illustrated 

 by his famous letter on earthworms, whose importance as soil- 

 makers and soil-improvers he clearly recognised. But this was 

 characteristic of Gilbert White's outlook — he had the vision of the 

 web of life. In the heat of the day the Hampshire cattle stand in 

 the forest ponds, and their dung, dropped into the water, forms a 

 culture-ground for aquatic insects — a very welcome addition to the 

 food-supply of fishes in places where "the water is hungry and the 



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