"DISSTSHINATION OF SEEDS. Gl 



srnist "be obtained from witliout. Different degrees of heat ai-e required by dif- 

 feren!- plants, but a temperature from 50' to 80° is most favorable to tliose of the 

 tempirate zones. Such is the genial v/armth supplied by tlie sun..- 



6.\Watcr is also requisite for softening the integuments, and for dissolving the 

 'dry nutriment stored up in the albumen, or the cotyledons. Tliis is supplied in 

 ^howjrs of rain and dev/) 



c^Oxygen is requisite, as seeii ahovc, for the conversion of starch into sugar 5^ 

 •a process always depending uj)on the fomiation and evolution of carbonic acid, as' 

 '^vcIl in thcseed as in the laboratery of the chemist. This is supplied by the 

 ""■vater and by the air.' 



rf^And, finally, dai-lmcss is favorable, because it is thi-ough the influence of 

 Sigh!, as v,-ill hereafter be shown, that plants absorb carbonic acid from the air, 

 ■decompose it, retain the carl)on itself, and give back the oxygen only. Light 

 wou d therefore tend to increase the quantity of carbon, rather than diminish it 

 Hence the seed should be buried in the soil.^ 



l&4<j. The riijenod seeds of most .plants have the power of retaining their vitality 

 for many years, if tirey are placed in circumstances which will neither cause them 

 to gfjrminate nor decay, such as a low or moderate temi^erature, with the absence 

 ■of nioisttirc. 1 Thus the seetls of maize have been kno\<Ti to grow when 30 years 

 old, rye 40 years, kidney beans 100 years, and the raspbeiTy and beach plum after 

 many centuiies.* 



{ 4. THE DISSE^^NATION OF SEEDS 

 l;':5. Is a subject highly curious and interesting; and when attentively consid- 

 ered, serves, like a thousand otlicr cases in the works of Nature, to illustrate the 

 wiscom and design of its great Author. ) By means of the coma, or pappus, 

 already described, the seeds of the tliistle, dandelion, and numerous other plants, 

 are wafted by winds to considerable distances, across rivers, mountains, and even 

 the ocean itself. y The Erigeron Car.adense, a wccA now common on both sides the 

 Atlr ntic, was supposed by Linnaeus to have been transported to EuroiJe from 

 Canada, ©f wMch country it is native. 



as Seeds are also furnished witli wings for the same purpose. Others are pro- 

 ^dded with hooks, or beards, by which they lay hold of men or animals, and are 

 thus, scattered far and vnAc.) 



6.w^ome seeds, as the Impaticns, which arc destitute of all such appendages, are 

 thrcAvn to some distance by tlie bursthig of the elastic pericarp. ' Rivers, streams, 

 and the cuiTcnts of the ocean, are all means of transporting seeds from country to 



* No instance of the longevity of seeds is more remarkable than that reJated by Dr. 

 Lindley. ' I Iiave before me,' says he, ' three plants of raspberries, raised from seeds which 

 ■were taken from the stomach of a man whose skeleton was found 30 feet below the surface 

 of the earth. He had been buried witli some coins of the emperor Hadrian, and it is therefore 

 probable that the seeds were ICOO or 1700 years old.' 



Several years ago, in the State of Maine, about 40 miles from the sea, some men, in dig- 

 ging a well, threw up some sand from a remarkable layer, about 20 feet below the surface, 

 and placed it by itself A year or two afterwards several shrubs sprung up from this sand, 

 grev/, produced fruit, and proved to be the beach-plura. 



