MONKEY'S DINNER-BELL 



The advantage of these wings and hairs is at once seen if 

 one compares the time that a fruit or seed takes to fall 

 through a given height, first with its wings or hairs, and then 

 after they have been cut off*. 



An Artichoke fruit, for instance, will take nearly eight 

 seconds to reach the ground from a height of a few feet. 

 But if you cut away its hairs, it will touch the ground in 

 a little more than one second. A Sycamore fruit of which 

 the wing has been removed falls to the ground in about 

 a quarter of the time that it takes when it has not been 

 injured, so that the wing helps it to fly to four times the 

 distance that it could reach if it had none. The Ash fruit 

 also remains twice as long in the air as it would do if it had 

 no wing ; and so on. 



We shall finish this chapter by describing two very extra- 

 ordinary cases. 



The Sandbox tree is a native of tropical America. The 

 fruit, as large as an orange, consists of a number of rounded 

 pieces, each with a single seed inside. When ripe each piece 

 splits off^, making a noise like the report of a pistol. The 

 plant is sometimes called the Monkey's Dinner Bell. These 

 pieces may be thrown to a distance of fifty-seven feet from 

 the parent plani. 



Even more remarkable are the hygroscopic grasses. There 

 are four of them, which are widely separated as regards 

 distribution, for one (Stipa capillata) lives in Russia, another 

 {Stipa spartea) in North America, a third (Aristida hygro- 

 metrica) is found in Queensland (Australia), and the fourth 

 {Heteropogon contortus) belongs to New Caledonia. 



Yet all these four grasses are said to kill sheep, and do so 

 in a manner that is almost identical. The mechanism is as 

 follows. 



266 



