753 



" If such plants are brought, whilst they are awake, from the dark- 

 ness of a cellar into the open air during the night, they slowly assume 

 their sleeping state. 



"In a warm cellar situated but little below the surface of the 

 ground, or in a dry room from which the light is carefully excluded, 

 the same events occur to such plants as if they were in a deep cellar, 

 though less perfectly. 



" Complete darkness neither increases nor diminishes the sensibi- 

 lity of Mimosa pudica. 



" Oxalis annua, the flowers of which, in the open air, open only 

 towards the middle of the day, remains in flower both night and day 

 in darkness. 



"Porleria hygrometrica is insensible to the hygrometrical variations 

 of the atmosphere, and assumes the condition of all the other sleep- 

 ing plants, although it is much more excitable. 



"We need not search among leguminous plants for such as most 

 readily assume the sleeping condition ; for Phyllanthus cantoniensis 

 and Porleria hygrometrica, one belonging to the Euphorbiacese and 

 the other to the Rutaceae, ought to stand at the head of the list." 



The above conclusions may account for some of the phenomena of 

 vegetable motions, but there are many others, even among the plants 

 which M. Fee has chosen for his experiments, that can in no wise be 

 referred to this cause, which seems much less satisfactory than Du- 

 trochet's theory of exosmose and endosmose, though in some measure 

 approximating to it. That theory clearly explains such phenomena 

 as are exhibited by the ripe fruits of Momordica elaterium and Im- 

 patiens ; and in the latter plant the ]ihenomena may be inverted by 

 placing fresh valves of the fruit in sugar and water, which, by pro- 

 ducing exosmosis, gradually straightens the curved valves and then 

 curves them in an opposite direction. But neither the theory of en- 

 dosmosis, nor M. Fee's modification, will account for the peculiar 

 movements of the leaves in Hedysarura gyrans, in which, while the 

 terminal leaflet is asleep, the two lateral leaflets are in continual mo- 

 tion, even during the night. 



That plants possess a system of organs somewhat analogous to the 

 nervous system of animals, seems at least to be rendered probable by 

 the results of experiments with various irritant and narcotic poisons, 

 upon such plants as exhibit, under ordinary circumstances, any pe- 



