THE PISPERSION OK SEEDS AND SPORES. 63 



the edge of the cup-like peridiura, attached by their 

 elastic stalk8, very much as the seed hangs outside 

 the capsule of Roxburgia and Magnolia. In a few 

 cases the entire plant-body appears to be hygro- 

 scopic, and advantage may be taken of this property 

 to aid in dissemination. Thus the Rose of Jericho 

 {Anastatica), a small annual found in sandy places 

 in Syria, has the curious habit of curling up its 

 leaves into a ball ; the rootlets become detached 

 from the dry earth, and the plant is rolled along 

 the ground by the wind. On reaching a moist spot, 

 the plant unfolds, its pods dehisce, and the seeds are 

 sown. From this remarkable habit Anastatica has 

 received its name of "the resurrection-plant." It 

 belongs to the order Cruciferse ; but an Australian 

 grass (Simplifex squarrosus) and a Brazilian Club 

 Moss {Lyco2'>odium squamatum) have also been de- 

 scribed as possessing the same curious wandering 

 habit. The stems of the Swan's-neck Moss are so 

 hygroscopic that on separation they can disperse 

 themselves very much like the grains of Avena 

 sterilis. 



From the examples now given it will be seen 

 how widespi'ead is the employment of hygroscopic 

 agency throughout the vegetable kingdom, wher- 

 ever the distribution of reproductive cells is in 

 question. Of the forces employed by man, perhaps 

 hydraulic power comes nearest it ; and it may not 

 be overstepping the proprieties of language to refer 

 to the contrivances just described as examples of 

 "vegetable hydraulics." Instances in which advantage 

 is taken of this property of vegetable tissues can, as 

 we have seen, be adduced from all classes of plants. 

 Thus it is called into play to promote the distribu- 

 tion of spores in Ferns, Horsetails, Mosses, and 

 Fungi ; for scattering the pollen in Urtica, Parietaria, 

 and Catasetutn ; for sheltering the pollen in most 

 anthers; and for the dispersion of seeds in Cardamine, 

 Impatiens, Sarothaynnus, Vicia, Viola, Oxalis, Ger- 

 anium, Mesevihryantliemuin, etc. With the exception 



