258 The Great World's Farm 



ferns contain so much of this that few animals care to 

 eat them, though they have their own particular cater- 

 pillars. 



Many plants are not merely disagreeable, but even 

 poisonous to mammals, though birds may eat the seeds, 

 and insects the leaves, with impunity; and others again 

 are of such a biting flavor as to raise blisters on the 

 tongue or skin. Some members of the buttercup family 

 are of this acrid nature, and the buttercup itself is said to 

 be avoided by cattle; but on the other hand, the deadly 

 nightshade, which is fatal to man, is eaten with impunity 

 by the rabbit. 



The Asclepias gigantea of the desert is so deadly that 

 the least drop of the poisonous milk contained in its leaves 

 and stem causes total blindness if it touches the eye; and 

 even those who cut the plant for fire-wood must beware of 

 so much as touching their eyes afterwards, since a merely 

 accidental rub may deprive them of sight. 



One would suppose, therefore, that the Asclepias was 

 so amply protected as to have no enemy at all; yet there 

 is one upon which its deadliness makes no impression 

 whatever; and this, the goat, devours it greedily, though 

 all other animals refuse and avoid it. 



Goats are indeed the most omnivorous and most 

 destructive of animals, and very few plants, or even trees, 

 are safe from them. Neither the thorns of the prickly 

 pear nor the flinty "needles" 'of young pines and flrs 

 afford any sufficient protection against them ; and yet even 

 the goat has its preferences, and is said to refuse lettuce, 

 while it will eat cabbage. 



Probably each plant has its own appropriate enemy — 

 really a friend to the race — whose office it is to check its 



