140 SENSITIVENESS OF THE APEX CHAP. III. 



(40.) Square of card gumined to apex: after 9 h. slightly 

 curved from card ; next morning radicle straight, and apex had 

 grown beyond the card. Eefixed another square laterally with 

 shellac ; in 9 h. deflected laterally, but also in the direction of 

 Sachs' curvature. After 2 additional days' curvature consider- 

 ably increased in the same direction. 



(41.) Little square of tin-foil fixed with gum to one side of 

 apex of a young and short radicle : after 15 h. no effect, but 

 tin-foil had become displaced. A little square of card was now 

 gummed to one side of apex, which after 8 h. 40 m. was slightly 

 deflected ; in 24 h. from the time of attachment deflected at 90 

 from the perpendicular and from the card ; after 9 additional 

 hours became hooked, with the apex pointing to the zenith. In 

 3 days from the time of attachment the terminal portion of the 

 radicle formed a ring or circle. 



(42.) A little square of thick letter-paper gummed to the 

 apex of a radicle, which after 9 h. was deflected from it. In 

 24 h. from time when the paper was affixed the deflection much 

 increased, and after 2 additional days it amounted to 50 from 

 the perpendicular and from the paper. 



(43.) A narrow chip of a quill was fixed with shellac to the 

 apex of a radicle. After 9 h. no effect ; after 24 h. moderate 

 deflection, but now the quill had ceased to touch the apex. 

 Eemoved quill and gummed a little square of card to apex, 

 which after 8 h. caused slight deflection. On the fourth day 

 from the first attachment of any object, the extreme tip was 

 curved towards the card. 



(44.) A rather long and narrow splinter of extremely thin 

 glass, fixed with shellac to apex, it caused in 9 h. slight 

 deflection, which disappeared in 24 h. ; the splinter was then 

 found not touching the apex. It was twice refixed, with nearly 

 similar results, that is, it caused slight deflection, which soon 

 disappeared. On the fourth day from the time of first attach- 

 ment the tip was bent towards the splinter. 



From these experiments it is clear that the apex of 

 the radicle of the bean is sensitive to contact, and 

 that it causes the upper part to bend away from the 

 touching object. But before giving a summary of the 

 results, it will be convenient briefly to give a few other 

 observations. Bits of very thin glass and little squares 



