CHAP. IV. CIKCUMNUTATION OF STOLONS. 221 



of the penultimate internode; and its chief seat was at the 

 distance of li inch from the apex; it appeared due to the 

 weight of the terminal portion, acting on the more flexible 

 part of the internode, and not to geotropism. The apex after 

 thus sinking down from 9.10 A.M. to noon, moved a little to the 

 left; it then rose up and circumnutated in a nearly vertical 

 plane until 10.35 P.M. On the following day (26th) it was ob- 



Fig. 90. 



ITa.m *^ 



Cotyledon umbilicus : circumnutation and downward movement of another 

 stolon, traced on vertical glass, from 9.11 A.M. Aug. 25th to 11 A.M. 27th. 

 Apex close to glass, so that figure but little magnified, and here reduced 

 to two-thirds of original size. 



served from 6.40 A.M. to 5.20 P.M., and within this time it moved 

 twice up and twice down. On the morning of the 27th the apex 

 stood as high as it did at 11.30 A.M. on the 25th. Nor did it 

 sink down during the 28th, but continued to circurnnutate about 

 the same place. 

 Another stolon, which resembled the last in almost every 



