

42 DEPARTMENT OF AGRICULTURE GEORGIA. [328] 



and the tube, no transferrence or change will be observed ; 

 but, if either be stronger than the other, a circulation will 

 be established, and the strong solution will be increased in 

 quantity until the two attain the same density. If two 

 different solutions be employed, as, for instance, sugar or 

 gum within the tube, and potash or soda without, a 

 circulation will in like manner take place, the preponder- 

 ance being toward the denser fluid, and in a degree propor- 

 tionate to the difference in density." 



This process goes on through the entire cellular system 

 of the plant, commencing with the root, and acting through 

 millions of cells during the ascent of the sap to the leaves, 

 where evaporation condensing the fluids in the cells at the 

 surface of the leaves, facilitates both osmose and capillary 

 attraction ; vital force, in the meantime, aided by chemical 

 action, appropriating in the process of assimilation the pre- 

 pared food for building up the various parts of the vegeta 

 ble organism. 



The roots of plants and trees generally correspond, to 

 some extent, in form with the part above ground. The 

 pine has a continuous stem extending to the top of the 

 tree ; the root also extends vertically into the ground to a 

 great depth, unless modified by impenetrable obstacles in 

 the sub-soil. The dogwood and red bud spread out 

 into fan-like lateral branches, having no continuous central 

 stem ; the roots have a corresponding arrangement, all 

 being distributed near the surface of the ground, with no 

 tap-root. Most biennial and perennial plants which are 

 outside growers (exogens) have tap-roots, while very few 

 inside growers (endogens) have them. The form of 

 plants may be somewhat modified by pruning the roots. 

 Advantage is taken of this principle by the gardener in 

 transplanting cabbage, lettuce and other plants which are 

 desired to form compact heads. When transplanted, the 

 tap-root is either broken or cut off. 



Root development is most active and necessary while 

 the plant is rapidly developing new growth, and preparing 



