THE WHITE ANT : A THEORY. 739 



ture. While admitting to the fullest extent the influence of worms in 

 countries which enjoy a temperate and humid climate, it can scarcely 

 be allowed that the same influence is exerted, or can possibly be ex- 

 erted, in tropical lands. No man was less in danger of taking a pro- 

 vincial view of nature than Mr. Darwin, and in discussing the earth- 

 worm he has certainly collected evidence from different parts of the 

 globe. He refers, although sparingly, and with less than his usual 

 wealth of authorities, to worms being found in Iceland, in Madagas- 

 car, in the United States, Brazil, New South Wales, India, and Cey- 

 lon. But his facts, with regard especially to the influence on the 

 large scale of the worm in warm countries, are few or wholly wanting. 

 Africa, for instance, the most tropical country in the world, is not 

 referred to at all ; and, where the activities of worms in the tropics are 

 described, the force of the fact is modified by the statement that these 

 are only exerted during the limited number of weeks of the rainy 

 season. 



The fact is, for the greater portion of the year in the tropics the 

 worm can not operate at all. The soil, baked into a brick by the 

 burning sun, absolutely refuses a passage to this soft and delicate ani- 

 mal. All the members of the earth-worm tribe, it is true, are natural 

 skewers, and, though boring is their supreme function, the substance of 

 these skewers is not hardened iron, and the pavement of a tropical 

 forest is quite as intractable for nine months in the year as are the 

 frost-bound fields to the farmer's plowshare. During the brief pe- 

 riod of the rainy season worms undoubtedly carry on their function in 

 some of the moister tropical districts ; and in the sub-tropical regions 

 of South America and India worms, small and large, appear with the 

 rains in endless numbers. But on the whole the tropics proper seem to 

 be poorly supplied with worms. In Central Africa, though I looked 

 for them often, I never saw a single worm. Even when the rainy sea- 

 son set in, the closest search failed to reveal any trace either of them 

 or of their casts. Nevertheless, so wide is the distribution of this ani- 

 mal that in the moister regions even of the equatorial belt one should 

 certainly expect to find it. But the general fact remains. Whether 

 we consider the comparative poorness of their development, or the 

 limited period during which they can operate, the sustained perform- 

 ance of the agricultural function by worms, over large areas in tropical 

 countries, is impossible. 



Now, as this agricultural function can never be dispensed with, it 

 is more than probable that Nature will have there commissioned some 

 other animal to undertake the task. And there are several other ani- 

 mals to whom this difficult and laborious duty might be intrusted. 

 There is the mole, for instance, with its wonderful spade-like feet, that 

 natural navvy who shovels the soil about so vigorously at home ; but 

 against the burned crust of the tropics even this most determined of 

 burrowers would surely turn the edge of his nails. The same remark 



