How Plants Secure Change of Location 399 



happen to resemble the larvae of ants are transported some dis- 

 tance towards their nests by the same more industrious than 

 sensible insects. It is possible, furthermore, that a somewhat 

 similar explanation applies to certain seeds or fruits which look 

 remarkably like beetles, as do some 

 Castor Beans, or like caterpillars, 

 as do some members of the Pea 

 Family (figure 170) ; for such seeds, 

 which are protected by hard coats 

 against digestion, are supposed by - ^^^^ 

 some naturalists to be swallowed 



"^Ppa-^ 



by birds in the behef that they are ^^°- i^o.-xhe pod of scorpiurus, sup- 



•^ '^ , posed to resemble a caterpiUar. 



really live insects. Again, brightly- 

 colored hard seeds, protectively coated, appear to be swallowed by 

 birds, as are other bright objects, simply because of their attract- 

 ive or conspicuous appearance. But these latter matters are doubt- 

 ful, and perhaps are fancies rather than facts, though we must re- 

 member that strangeness or seeming improbability are not valid 

 scientific objections to any explanation of a natural phenomenon. 

 Not only birds and small mammals, but also bats, snails, insects, 

 fish, and perhaps other animals, have been detected in carrying 

 seeds by some one or the other of the various ways we have 

 mentioned. The subject is by no means exhausted, and most 

 interesting discoveries without doubt still await the keen-sighted 

 and persistent observer. 



To complete the subject of transport by animals we must 

 mention the action of man, though his agency is of course in- 

 cidental and not adaptational. Unintentionally he has spread 

 weeds from country to country, until some occur all around the 

 world, while deliberately he has carried the plants that are valua- 

 able to him to all parts of the earth. Indeed, upon this latter end 

 he concentrates much effort and thought, reaching their culmi- 

 nation in the deliberate and systematic attempts of our national 

 Department of Agriculture to gather useful plants from all parts 



