138 IRRITABILITY OF VEGETABLES. 



feetly right : the mistake of my amenuansis, who inserted 



*' washed off" instead of " rubbed off," has caused an 



apparent confusion in the description. No water can enter 



the air vegsels, except when the adjoining parts are much 



torn. 



Morion rf the The motion of the hair in the air cylinder is caused by 



a pin, which j entering the widest end of the hair, runs 



through the side of the air vessel into the next water vessel. 



The water rising contracts the spiral, pushes the pin, 



and the hair, which remained before parallel to the side 



of the vessel, now starts up horizontally; and, as the whole 



circle of hairs rises, each in the same manner and at the 



same time, meeting with their, points, if any insect has 



placed itself in the way, it will be crushed or run through 



(as I have often seen it) by the sudden motion of the hairs. 



Tfc# pte»t the No insect certainly can get into the air cylinders, but by 



^ j, °* ,™ a " y the dilapidations of some of the adjoining vessels; but this 



must often happen, as these plants are the food of many of 



:*tvl pe?fnpsof the diminutive slug kind; and I doubt whether the ciearia 



. c '^ aTU lemiiEe (which is the only species I have found on the hairsl 



lexau'f . , . ■ * 



do not also i'ctd on it. 



I am, Sir, 



Your obliged servant, 



AGNES IBBETSQN. 



XI. 



Oh the Irritability of the Son-thistle, and other Plants, with 

 farther observations on the Irritability of Vegetables: 

 by D. J. Carradori*. 



Irritability of Ji HE lettuce is not the only plant that possesses a 



ptosis. striking degree of irritability during the period of flowering, 



the prickly sowthistle fsonchus asperj has this faculty 



Shown In she a t the same season. In fact it transmits and gives out a 



Je, 



milky fluid, like the lettuce, when it is irritated, or punc- 



* Abridged from the Journ. de Phys. vol. LXVII, p. 405. 

 + Experiments on tlie Irritability of the lettuce, Mem. of the 

 Italian Society of Sciences, vol. XII. 



tured 



