Growth and Movement. 



101 



OBSERVATIONS. 



95. With waterproof India ink make marks two millime- 

 ters apart on some rapidly growing stem, beginning at the 

 apex and extending downward for several internodes. Ob- 

 serve from time to time whether the marks become sepa- 

 rated farther by the elonga- 

 tion of the stem, and whether 



growth seems to be more rapid 

 in one region than in another. 

 Where does growth in length 

 seem to have ceased? Com- 

 pare with similar observations 

 on the growth of roots. 



96. By means of the simple 

 apparatus illustrated in Fig. 

 43 observe the rate of growth 

 of some rapidly growing stem. 

 Compare the amount of growth 

 in the daytime with that for 

 the same number of hours in 

 the nighttime. 



97. By means of recorded 

 measurements, compare the 

 rate of "growth of two plants 



of the same kind, one of which is in a dry soil, and the 

 other under the same conditions, with the exception that it 

 is kept well supplied with water. What conclusion do you 

 reach as to the use of water in growth ? 



98. Cover one shoot of a plant which branches near the 

 ground (such as the potato) with something to exclude the 

 light, and leave the remaining shoots uncovered. After a 

 few days compare the lengths of the newly formed inter- 



FTG. 43. 



A simple form of Auxanometer. A 

 thread is attached to the apex of the 

 plant and passed over the pulley and 

 held taut by a weight which is only 

 heavy enough to move the pointer as 

 the plant elongates. The arc can be 

 made of heavy manila paper and all 

 other parts of light wood. 



