CH. VII] 



INJURY. 



177 



fine sand-paper (which adheres well) are to be fixed to the 

 tips of bean roots by a thin layer of strong shellac varnish 

 which sets hard very quickly. It is important that the 

 squares of card should be attached to the slope of the root- 

 apex, and that they should be either on the right or left of 

 the root-tip : if they are on the anterior or posterior face of 

 the root, the resulting curvature will be in the plane of 

 the cotyledons and therefore liable to be interfered with 

 by Sachs' curvature which occurs in the same plane. The 

 side on which the card must be placed will be understood 

 from Fig. 33, which represents bean roots with cards 

 attached, and showing various degrees of curvature. 



FIG. 33. Exp. 207. 

 (From The Power of movement, fig. 65, p. 134.) 



D. A. 



12 



