CaAP. XI. TRANSMITTED EFFECTS: VICIA. 



5F1 



the whole growing portion ; and after the 24 h. this part had 

 a mean length of 37 mm., so that it had increased to more 

 than 3 J times its original length; but it should be remembered 

 that these beans had been exposed to a rather hightempeiature. 

 Nineteen young radicles with cauterised tips were extended 

 at different times horizontally over water. In e-very trial an 

 equal number of control specimens were observed. In the first 

 trial, the tips of three radicles were lightly toucted with the 

 caustic for 6 or 7 seconds, which was a longer application than 

 usual, After 23 h. 30 m. (temp. 55°-56° F.) these three radicles 



Vicia faha . state of radicles which had been extended horizontally for 

 23 h. 30 m. : A, B, C, tips touched with caustic ; D, E, F, tips uncaute- 

 rised. Lengtlis of radicles reduced to one-half scale, but by an accident 

 the beans themselves not reduced in the same degree. 



A, B, (Fig 196), were still horizontal, whilst the three control 

 specimens had become within 8 h. slightly geotropic, and 

 strongly so (U, E, F) in 23 h. 30 m. A dot had been made on 

 all six radicles at 10 mm. from their tips, when first placed 

 horizontally. After the 23 h. 30 m. this terminal part, originally 

 10 mm. in length, had increased in the cauterised specimens to 

 a mean length of 17'3 mm., and to 15'7 mm. in the control 

 radicles, as shown in the figures by the unbroken transverse 

 line ; the dotted line being at 10 mm. from the apex. The con- 

 trol or uncauterised radicles, therefore, had actually grown less 



