HOW THE PLANT LIVES 131 



The stem, therefore, has grown throughout its length rather than 

 from the end. Bailey, "Lessons with Plants," p. 322. 



206. Germinate a squash seed between layers of blotting-paper 

 or cloth. When the root has grown an inch or two lay the plantlet 

 on a piece of paper. Then lay a rule alongside of it, and make 

 a mark (with indelible ink) one-quarter of an inch, or less, from 

 the tip, and two or three other marks at equal distances above 

 (Fig. 44). Now carefully replace the seed. Two days later, 

 examine it; we shall most likely find a condition something like 

 that in Fig. 45. It will be seen that the marks E, C, B, are prac- 

 tically the same distance apart as before, and they are also the 

 same distance from the peg, A A. The point of the root is no 

 longer at D D, however, but has moved on to F. Bailey, "Lessons 

 with Plants," p. 321." 



207a. We now see that the "sap" of trees is a very complex 

 substance. It is the juice or liquid in the plant. The liquid 

 which first comes in at the root is water, with very dilute pro- 

 portions of various substances. But the sap also carries the 

 products of assimilation to all parts of the plant, to build up the 

 tissues. In common speech, the upward-moving water, recently 

 taken in from the soil, and known as the "transpiration stream,'' 

 is often called crude sap; and the liquid carrying sugars and 

 other organic compounds is called elaborated sap. 



209a. See the discussions and pictures of moving parts in 

 Bailey's "Lessons with Plants," pp. 396-406; also Barnes' "Plant 

 Life," pp. 188-208; Atkinson's "Elementary Botany," pp. 82-92; 

 Arthur and MacDougal's "Living Plants," Chapters i.-iv., and 

 other botanical treatises. 



