CHAP. I, 



BRASSICA. 



11 



Fig. 1. 



been much greater, for at the close of our observations the tip, 

 instead of standing vertically upwards, had become bowed 

 downwards through geotropism, so as almost to touch the zinc 

 plate. As 'far as we could 

 roughly ascertain by measure- 

 ments made with compasses 

 on other seeds, the tip alone, 

 for a length of only yo to 

 T o of an inch, is acted on 

 by geotropism. But the trac- 

 ing shows that the basal part 

 of the radicle continued to 

 cireumnutate irregularly dur- 

 ing the whole time. The 

 actual extreme amount of 

 movement of the bead at the 

 end of the filament was nearly 

 05 inch, but to what extent 

 the movement of the radicle 

 was magnified by the fila- 

 ment, which was nearly I inch 

 in length, it was impossible 

 to estimate. 



Another seed was treated and observed in the same manner, 

 but the radicle in this case protruded '1 inch, and was not 



Fig. 2. 



Brassca oleriacea : circumnutation of 

 radicle, traced on horizontal glass, 

 from 9 A.M. Jan. 31st to 9 P.M. 

 Feb. 2nd. Movement of bead at 

 end of filament magnified about 

 40 times. 



\ 



Brassica oleracea : oircumnutating and geotropic movement of radicle, 

 traced on horizontal glass during 46 hours. 



fastened so as to project quite vertically upwards. The filament 

 was affixed close to its base. The tracing (Fig. 2, reduced by 

 half) shows the movement from 9 A.M. Jan. 31st to 7 A. AT. 

 Feb. 2nd; but it continued to move during the whole of tho 



