THE WORK OF FRUITS 



321 



thrown to a distance of several feet. Try to discover 

 by what mechanism this is accomplished ; notice the 

 twisting of the pod which accompanies the expulsion 

 of the seeds ; how is this twisting brought about? 

 Many other members of the Pea family have this 

 peculiarity. Interesting to study in this connection q 

 are the fruits of the Touch-me-not, Violet, q q 

 Wood-sorrel (Oxalis), Witch-hazel and many q 

 others. The Squirting Cucumber (Fig. 170) q 

 throws its seeds twenty feet or more by 

 means of a curious contrivance. 

 The end of the stalk is enlarged to 

 form a sort of stopper. The fruit 

 is filled with a mucilaginous sub- 

 stance in which the seeds are im- 

 bedded. When this has absorbed 

 considerable water, sufficient pres- 

 sure is generated so that a touch 

 causes the stopper to be ejected, 

 and the seeds are sent flying. 



While these wonderful contrivances sei've excel- 

 lently to distribute the seeds for a short distance, 

 they are but poor and ineffective compared to those 

 which make use of the wind as a carrier. Thistle- 

 down flies to gi-eat distances ; the fruits of Maples, 

 Elms, Pines, Birches, etc., travel far and wide by 

 the aid of the wind. On windy days, when the snow 

 is covered with a smooth crust, such fruits go skim- 



170. Fruit of Squirting Cu- 

 cumber in the act of ex- 

 pelling the seeds: the 

 fruit absorbs water un- 

 til sufficient pressure is 

 generated to eject the en- 

 larged stopper- like end 

 of the stalk and the seeds 

 with it. 



