CHAP. V. FUNCTION OP REPRODUCTION. 249 



roots at a distance from the trunk, all of which are 

 capable of becoming so many distinct trees, under fa- 

 vourable circumstances. Man has availed himself of 

 this property, to extend the means which nature has 

 provided for the propagation of the species ; and by 

 placing cuttings, slips, and buds under proper treat- 

 ment, he forces them to throw out roots ; or he grafts 

 them on other stems, where they adhere and develop 

 as so many separate and independent individuals. The 

 process by which any detached portion of a plant be- 

 comes a distinct individual, similar to that from which 

 it was derived, depends upon the power it possesses 

 of reproducing those organs or parts in which it may 

 be defective. Thus the ascending organs develop roots; 

 and these again, produce buds from which the ascend- 

 ing organs proceed. 



(244.) Reproduction. But although the propa- 

 gation of many plants may be effected by the means 

 here alluded to, and although some species are more 

 frequently and readily propagated by subdivision, than 

 by the method which we are about to describe, yet 

 the greater number of plants, and at least all those 

 which bear flowers, secure the continuation of their 

 species by a distinct process, of a very different nature. 

 This constitutes the function of " reproduction," pro- 

 perly so called ; which consists in the formation of 

 seeds, containing the germs of future individuals. This 

 function of reproduction is to the species, what life is 

 to the individual a provision made for its continued 

 duration on the earth. The more minute details of the 

 process by which the function of reproduction is carried 

 on, and the germ or " embryo" of the future plant be- 

 comes generated in the seed, were never understood till 

 of late years; nor are they even yet so completely 

 ascertained as we may one day hope to find them. 

 The general function of reproduction may be consi- 

 dered as completed in five different periods ; much in the 

 same manner as we ascribed seven periods or processes 

 to the function of nutrition. 



