214 CIKCDMNUTATION OF STOLONS. Chap, ly 



fore, sooner or later, bend to all sides; but after a 

 stem has bent in any one direction, it commonly 

 bends back at first in nearly, though not quite, the 

 opposite direction ; and this gives the tendency to 

 the formation of ellipses, which are generally narrow, 

 but not so narrow as those described by stolons and 

 leaves. On the other hand, the figures sometimes 

 approach in shape to circles. Whatever the figure 

 may be, the course pursued is often interrupted by 

 zigzags, small triangles, loops, or ellipses. A stem 

 may describe a single large ellipse one day, and 

 two on the next. With different plants the com- 

 plexity, rate, and amount of movement differs 

 much. The stems, for instance, of Iberis and Azalea 

 described only a single large ellipse in 24 h. ; 

 whereas those of the Deutzia made four or five deep 

 zigzags or narrow ellipses in 11 J h., and those of the 

 Trifolium three triangular or quadrilateral figures 

 in7h. 



CiRCUMNUTATlON OP StOLONS OE EuNNEES. 



Stolons consist of much elongated, flexible branches, 

 which run along the surface of the ground and form 

 roots at a distance from the parent-plant. They are 

 therefore of the same homological nature as stems; 

 and the three following cases may be added to the 

 twenty previously given cases. 



Fragaria (cultivated garden var.) : Bosaceae. — A plant growing 

 in a pot had emitted a long stolon ; this was supported by a 

 stick, so that it projected for the length of several inches hori- 

 zontally. A glass filament bearing two minute triangles of 

 paper was affixed to the terminal bud, which was a little up- 

 turned ; and its movements were traced during 21 h., as shown 

 in Fig. 85. In the course of the first 12 h. it moved twice up 

 and twice down in somewhat zigzag lines, and no doubt tra- 

 velled in the same manner during the night. On the following 



