0"N THE IRRITABILITY OF VEGETABLES. OJ$ 



vmh a viscid fluid (probably) not only for alluring the little 

 insects, but also for retaining- them, until the contraction of 

 the hairs (which is not immediate) shall begin. Now if the 

 insect has been unablt to overcome the tenacity of the fluid, 

 it will soon be imprisoned by the hairs bending over it, and 

 finally will either be killed by the contraction of the leaf, or 

 retained in it until it dies. This contraction will continue 

 until all is quiet, and even until the leaf becomes accus- 

 tomed to its action, and of course suiters no farther stimu- 

 lus ; then most of the hairs and the leaf will expand and re- 

 sume their former situations. 



This is the manner then by which the flies &c. are im- Of what use is 

 prisoned ; but it may be inquired also, of what use are the ^e olauit >" 

 insects to the plants? I think there can be little doubt, 

 but that they are of some important use in the vegeta- 

 ble economy, or why should so many thousand insects be 

 thus destroyed ? Dr. Smith in his introduction to botany, 

 after mentioning an interesting circumstance concerning the 

 sanacenia adunca and purpurea, says: " Probably the air 

 " evolved hy these dead flies may be beneficial to vegeta- 

 " tion." And again: " probably the leaves of the dionoea 

 " muscipula, as we! 1 as the droserae, catch insects for a similar 

 « reason." On this subject I can say nothing at present, 

 but must think Dr. Smith's explanation very ingenious, 

 and probably just : but I cannot avoid asking one question, 

 viz. As the flies in course of time are reduced to a pulpy state, Perhaps ab- 

 both in the dionoea muscipula, and in the droserae, is it not so / bed as nu * 

 probable, that some of the pulpy mass may be absorbed, 

 and so prove as useful to the plant as the putrid effluvia? 



P. S. Since the above observations were written out, 

 about five weeks ago, two papers ou the motious of vegeta- 

 bles have appeared. The 1st in a supplement to the 23d M rs Ibbet- 

 vol. of Nicholson's Journal, and the yd in the 107th num- s ° 1 ^ theor y 

 ber, or that for the present month. The author of both is 

 Mrs. lbbeison, whose knowledge, industry, and persever- 

 ance deserve the highest encomiums. She endeavours to 

 explain not only the motions of plants, but also their sleep, 

 their sensibility, and their volition, by the ehan-es pro- 



Vol. XXIV. Dec. 1809. T duced 



