VEGETABLE DISSEMINATION. 511 



the fields and prairies as driven by the wind, veritable "tumbling-weeds," scat- 

 tering not only their seeds, but often those of other plants that have become 

 entangled in them. The rose of Jericho (Anastatica) that grows in the arid 

 deserts of both Africa and Asia, when mature, rolls up in a ball, becomes de- 

 tached from the ground and goes rolUng before the wind till it reaches a moist 

 spot, or there falls a slight sprinkling of rain, when it immediately unrolls, the 

 pods open and the seeds fall out and germinate within eighteen hours, so that by 

 the time the transient moisture has disappeared the young plant has taken root 

 and is ready to grow in spite of the scorching sun and blasting winds of the 

 desert. While a few plants thus travel and sow their own seeds, others stay at 

 home and throw them so as to scatter them to various distances. Some gerani- 

 ums when the pod bursts throw their seeds out by a httle spring that is arranged 

 in it for that purpose. 



In the pods of beans the fiber is arranged at an oblique angle with the linear 

 direction of the pod and when it becomes dry and bursts, this arrangment of the 

 fiber causes the two halves of the pod to suddenly twist spirally, by which motion 

 the seeds are thrown out to some distance. The castor-oil bean also has the 

 habit of throwing its seeds out by a sudden springing of the material of the pod 

 Almost every one has noticed how the parts of the pod of the touch-me-not (im 

 patiens) will curl up with a sudden spring and scatter the seeds in all directioiis 

 on being touched or shaken. The wild touch-me-not, or jewel-weed, acts in the 

 same manner but with even still greater energy. In cyclanthera, the fruit of 

 which is not symmetrical, one side being flat and the other round, when ripe 

 suddenly explodes scattering its seeds on all sides. 



In arcentholium, a relative of the mistletoe, and a parasite of the juniper, 

 the seeds are thrown from one tree to another. The squirting cucumber, a well 

 known plant of southern Europe, as it approaches maturity, becomes so gorged 

 with fluid that when fully ripe it bursts near the place of attachment to the stem 

 and throws its contents to a distance of several yards. The discharge is accom- 

 panied by a report as of a toy pistol. Persons venturing to touch one, or even 

 passing near them are liable to be greeted with the contents of this vegetable 

 pop-gun. Many other plants that project their seeds might be named, but these 

 are sufficient for our purpose. Water is also an agent in the dispersion and dis- 

 semination of seeds. During heavy rains and floods nearly all kinds of seeds are 

 liable to be carried down from the higher ground into the rivers and by them 

 transported long distances. These eventually find a resting place in the sedi- 

 ment of some island, or low bottom land, and spring up and flourish luxuriantly. 

 The currents of the ocean also become the means of transport for seeds that are 

 adapted to floating. The cocoanut, whose corky shell so well adapts it to this 

 mode of conveyance, has thus been carried to all the islands of the tropics. 



In many cases animals are agents in the dispersion of the seeds of plants. 

 Numerous species of trees and plants bear edible seeds and nuts that are gathered 

 by various animals and birds as winter stores, some of which are lost or forgotten 

 and so are left to grow the following year. Many kinds of fruit are eaten by 



