Chap. in. OF THE EADICLE OF THE BEAN. 136 



w(ire fixed either behind, causing a curvature in direct 

 opposition to that of Sachs', or more commonly to the 

 right or left sides. For the sake of brevity, we will 

 speak of the bits of card, &c., as fixed in front, or 

 behind, or laterally. As the chief curvature of the 

 radicle is at a little distance from the apex, and as 

 (he extreme terminal and basal portions are nearly 

 straight, it is possible to estimate in a rough manner 

 the amount of curvature by an angle ; and when it is 

 said that the radicle became deflected at any angle 

 from the perpendicular, this implies that the apex was 

 turned upwards by so many degrees from the down- 

 ward direction which it would naturally have followed, 

 and to the side opposite to that to which the card was 

 affixed. That the reader may have a clear idea of the 

 kind of movement excited by the bits of attached 

 card, we append here accurate sketches of three ger- 

 minating beans thus treated, and selected out of 

 several specimens to show the gradations in the 

 degrees of curvature'. We will now give in detail a 

 series of experiments, and afterwards a summary of 

 the results. 



In the first 12 trials, little squares or oblongs of sanded card, 

 1'8 mm. in length, and 1-5 or only 0"9 mm. in breadth (i.e. ■071 

 ot an inch in length and '059 or 'OSS of an inch in breadth) were 

 fixed with shellac to the tips of the radicles. In the subsequent 

 trials the little squares were only occasionally measured, but 

 were of about the same size. 



(1.) A young radicle, 4 mm. in length, had a card fixed bo- 

 hind: after 9 h. deflected in the plane in which the bean is 

 flattened, 50° from the perpendicular and from the card, and in 

 opposition to Sachs' curvature : no change next morning, 23 h. 

 from the time of attachment. 



(2.) Eadicle 5'5 mm. in length, card fixed behind : after 9 h. 

 deflected in the plane of the bean 20"^ from the perpendicular 

 and from the card, and in opposition to Sachs' curvature : after 

 23 h. no change. 

 10 



