3U 



OK TBE IRRITABILITY OF THE BARBERRY. 



siderate rejection of a theory, beautiful on account of its 

 unity and simplicity. 



I am, sir. 

 Your most obedient servant, and constant reader, 



F. D. 



IQtk diarchy 1811. 



X. 



Observations respecting the Irritahihty of the Barberry^ Ber* 

 beris communis. By Mr. Robert Lyall, Surgeon^ Mem^ 

 her of the Royal Physical Society of Edinburgh, and corres- 

 ponding Member of the Literary and Philosophical Society 

 at Manchester, Communicated by the Author, 



Br. Sm;th*s 

 expexknents 

 on them. 



IrritabiUtjr of ,/TCLTHOUGH it was known many years ago, that the 

 th* haub^^"^ ^^ stamina of the barberry contracted when irritated by mecha- 

 nical stimuli, 5'et till the time when Dr. Smith published 

 his observations relative to the subject*, our knowledge on 

 this point was but incomplete. 



Dr. Smith, in order to ascertain what part of the stamina 

 was endued with irritability, cut oflP one of the petals 

 of the flower so carefully as not to touch the stamen, that 

 stood next it ; then with a very slender piece of quill 

 he touched the outside of the filament, which had been 

 next the petal, but it remained perfectly immovable. 

 With the same instrument he then touched the back of 

 the anthera, then its top, its edges, and at last its inside ; 

 still without any effect. — But the quill being carried from 

 the anthera down the inside of the filament, it no sooner 

 touched that part, than the stamen sprung forwards with 

 great vigour to the stigma. From the result of this and 

 other experiments Dr. Smith concludes, ** That the mo- 

 tion above described was owing to a high degree of irritabi- 

 lity in the inside of each filament, next the germcn, by 

 which, when touched, that side becomes shorter than the 

 other, and consequently the filament is bent towards t\^^ 

 germen." ^« 



Manner in 

 which he ac- 

 coums for it. 



♦ Phil. Trans, for 178$. 



Bonnet'ft 





