92 ORGANIC STRUCTURE. 



sider these two divisions of the plant in any other 

 light than as " correlative parts" necessary to the 

 system ; and therefore by no means entirely inde- 

 pendent, notwithstanding we often see them acting 

 in the absence of each other : felled trees produce 

 shoots, and the roots of trees and deep rooting herbs 

 will continue to throw up sap for a long time after 

 the head and stem are cut off. 



The Collet. This is that part of the axis which 

 divides the stem from the root of a seedling. It is 

 the seat of the cotyledons the crown of the roots 

 and the base of the stem. It is certainly a dis- 

 tinct member of the plant, especially in the early 

 stages of life ; and has been so considered by many 

 eminent botanists. Fischer and Treviranus call it 

 centrum vegetationis ; Turpin termed it ligne mtdi- 

 ane ; Professor Hayne of Berlin calls it nodus 

 indifferentialis ; and Lamarck, and many others, the 

 life-knot, (a. Fig. 8.) 



If a seedling of an herbaceous plant, and of many 

 kinds of trees, be cut over below the collet, the root 

 invariably dies ; but if above, except some kinds of 

 Coniferce, Palmce, &c., the root will contiryie to 

 live, and new shoots will be produced from the collet. 



Trees whose root, stem, and branches are studded 

 with incipient buds, as the myrtle for instance, con- 

 tain a much greater number crowded together in the 

 collet than in any other part. It is on this account 

 that portions of the protuberant part of it are chosen 

 and planted for the purpose of propagating the olive, 

 in the south of Europe. The nodes of jointed stems 



