2o8 The Great World's Farm 



Hitherto we have confined our attention to the welcome 

 guests; but there are unwelcome ones also, and the very 

 snails last considered have two sides to their character. 

 Indeed, the beneficent side is not the one with which we 

 are familiar, being rather a recent discovery, while their 

 mischievous propensities are well and widely known. 

 Even the arums which welcome them as pollen-carriers 

 need some sort of protection against them. They have 

 to be tempted to undertake what to them is really an 

 immense journey, by special attractions, otherwise, being- 

 voracious eaters, they would simply begin to devour the 

 first leaf they came across. Then, when they have started, 

 all loitering by the way is sternly discouraged, for arum- 

 leaves are acid, and even poisonous; so there is no temp- 

 tation to make a meal of them. 



Useful as they are to arums and arum-like plants, they 

 are not generally desirable as visitors, and are not often 

 found in flowers, bristles and prickles being enough to 

 turn them back at once. No wingless visitors are gen- 

 erally welcome, for they crawl slowly, lose pollen by the 

 way, by getting it rubbed off them, and are usually so 

 indiscriminate in their tastes that they go as readily to 

 one blossom as another, and it is quite a chance what 

 pollen, if any, they may bring with them. 



It is, of course, not to the plant's interest that its 

 pollen and nectar should be taken by insects which plunder 

 without making payment in return, as it is thereby robbed 

 of its means of attracting other and more useful insects. 

 But the useless ones are just as fond of nectar as the use- 

 ful, just as quick, too, to find it out, wherever it may be 

 hidden, so that many devices are needed to baffle these 

 unwelcome guests. 



