1904.] 



Notes on the Statolith Theory of Geotropism. 



487 



Fig. 2. 



A 



B 



dotted lines in fig. B. Fig. 3 shows the similar behaviour of tertiary 



The line representing the secondary root is vertical and unbroken, 

 the curved lines springing from it on the left and right are tertiaries, 

 ■and are made up of separate sections, each of which represent the 

 growth on one day. The marks 1 and 1 were painted on May 12, 1903. 

 They show that the R and L roots grew out at very different angles with 

 the secondary root. This is accounted for by the fact that while 

 sections 1 and 1 were developing the left end of the trough was 

 raised (25°). If the figure is turned to this position it will be seen 

 that 1 and 1 make roughly equal angles with the horizon. 



After tracing sections 1 and 1 the trough was raised so as to make 

 40° with the horizon, the left end being still the higher. 



On May 13, section 2 was painted on the R side, section 2 on the 

 L side could not be clearly seen. The trough was now placed at an 

 angle of 32°, being, however, reversed, so that the R end was higher. 



May 14, sections 3 painted on both sides. It will be seen that root 

 R has begun to assume its proper angle below the horizon, whereas 

 L has continued to grow nearly in line with section 1. On the 

 following days (sections 4 and 5) L bent upwards. This is a striking 



roots. 



Fig. 3. 



