rOL. LXXVIII.] PHILOSOPHICAL TRANSACTIONS. 421 



XII. On the Irritability of Vegetables. By Ja. Edw. Smith*, M. Z)., F. R. S. 



p. 158. 



Having often Jieard that the stamina of the Barberry, Berberis communis, were 

 endued with a considerable degree of irritability, I made the experiment in 

 Chelsea garden, May 25, 1786, on a bush then in full flower. It was about 

 1 o*clock p. M. the day bright and warm, with little wind. The stamina of such 

 of the flowers as were open were bent backwards to each petal, and sheltered 

 themselves under their concave tips. No shaking of the branch appeared to 

 have any effect on them. With a very small bit of stick I gently touched the 

 inside of one of the filaments, which instantly sprung from the petal with con- 

 siderable force, striking its anthera against the stigma. I repeated the experiment 

 a great number of times; in each flower touching one filament after another, 

 till the tip of all the 6 were brought together in the centre above the stigma. I 

 took home with me 3 branches laden with flowers, and placed them in a jar of 

 water, and in the evening tried the experiment on some of these flowers, then 

 standing in my room, with the same success. 



In order to discover in what particular part of the filaments this irritability re- 

 sided, I cut oflf one of the petals with a very fine pair of scissars, so carefully as 

 not to touch the stamen which stood next it: then, with an extremely slender 

 piece of quill, I touched the outside of the filament which had been next the 

 petal, stroking it from top to bottom; but it remained perfectly immoveable. 

 With the same instrument I 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. This 

 was often repeated with a blunt needle, a fine bristle, a feather, and several 

 other things, which could not possibly injure the structure of the part, and al- 

 ways with the same effect. To some of the antherae I applied a pair of scissars, 

 so as to bend their respective filaments with sufficient force to make them touch 

 the stigma; but this did not produce the proper contraction of the filament. 

 The incurvation remained only so long as the instrument was applied; on its 

 being removed, the stamen returned to the petal by its natural elasticity. But 

 on the scissars being applied to the irritable part, the anthera immediately flew 

 to the stigma, and remained there. A very sudden and smart shock given to 

 any part of a stamen would sometimes have the same effect as touching the irri- 

 table part. 



Hence it was evident, that the motion above described was owing to a high 

 degree of irritability in the side of each filament next the germen, by which, 



• Founder and President of the Linnsean Society, and highly distinguished for his botannical 

 works. 



