ON THE IRRITABILITY OF VEGETABLES. 



CS7 



*' The ant died in 15 minutes, which was before all the hairs 

 " had bent themselves. On repeating this experiment, I 

 " found the effects to follow sooner or later according to the 

 " state of the weather. At eleven in the morning a small 

 " fly, placed in the centre of the leaf, died sooner than the 

 *' ant had done, the hairs bent themselves as before, and at 

 ** five in the evening the leaf was bent together, and held 

 " the fly shut up. The same experiments being made on 

 ■*' the drosera longifolia, the same eifects followed, but more 

 " rapidly. I observed, that in sultry weather, and hot snn- 

 " shine, when the drops of juice upon the points of the 

 " hairs are largest, the experiment succeeds best. If the 

 *' insect beasmall one, sometimes only one edge of the leaf is 

 " folded up ; hence it should seem necessary, that the in- 

 ** sect should stir all the hairs of the leaf." 



Roth also found, that the hairs bent themselves when he Found to con. 

 touched them with the point of a needle, with a hog's bristle, tract whea 

 &c. ; but that they returned to their former position after a needle. 

 certain time. He remarked the same contraction when he • 

 placed a piece of wood the weight of an ant upon the leaves ; 

 but that the impression made by the point of a needle re- 

 mained longest. Although Withering points out the most 

 of these circumstances particularly with a view to excite the 

 attention of botanists to the species of drosera, yet I have 

 not met with any account of experiments made since the 

 time he wrote, in the year 179.6. 



For the last 5 months of the present year I have almost The con(rar ._ 

 every day had these plants under my eye, either at home or tion takes 

 abroad in the country. For my own part I must confess, £ ^L Ut 

 that I have never seen that rapid contraction of the leaves of 

 the drosera rotunda, which is, mentioned by Mr. Gardom; ' 

 but in all the experiments which I have made, I have ob- 

 served that the contraction was gradual, though it seldom 

 failed to happen, if the plant was in good condition. In 

 some plants I have seen the contraction take place in nearly 

 the time mentioned by Roth ; but in most cases it has hap- 

 pened, that an honr was necessary for the complete bending 

 of all the hairs, and that it required some hours more for 

 the perfect shutting up of the leaves. In some plants I 

 have seen the hairs and leaves nearly expanded even some 



hours 



