146 - Irritability of Plants. 



the Browning-With silvered-mirror telescopes, with, a power 

 of 120. 



When the cloudless intervals permitted, the shadows of the 

 three satellites (1, 3, and 4) on the disk were sharp, and as 

 black as ink, contrasting boldly with the brilliant portions of 

 the planet, and making the coppery tint of the belts more 

 conspicuous by their deviation from the much darker shadow 

 tones. Fortunate observers saw the entrance of the third 

 satellite on Jupiter's disk at 8.14 p.m., eclipse of the second 

 satellite, the entry of the fourth and first on the disk, preceded 

 by their shadows, the passage off the disk of these satellites 

 and their shadows, and also the reappearance of the second 

 satellite from behind Jupiter. Few could expect to be so 

 lucky as to see all the incidents, which a perfect continuance 

 of fine weather could disclose ; but a great many saw enough 

 to make the evening of the 21st of August memorable in their 

 astronomical experience. Near Dublin, the Hon. Mrs. Ward 

 informs us the sky was propitious for nearly the whole time, 

 though clouded when the fourth satellite left the disk, and the 

 series of phenomena ended. 



IRRITABILITY OF PLANTS. 



BY M. CH. ELONDEAU. 



(From " Comptes JRendus.") 



We have undertaken, in the course of this year, a number of 

 experiments on the irritability of plants, which show that the 

 faculty which some of them, and especially the sensitive plant, 

 possesses of executing movements which appear voluntary, 

 may be suspended by many agents, such as ether, chloroform, 

 carbonic oxide, and spirit of turpentine — all of which are known 

 to act upon the nervous system of animals. 



Amongst these experiments, one appears to us of sufficient 

 interest to deserve the attention of the Academy of Science ; 

 it relates to the action of the electric current on the Mimosa 

 pudica (sensitive plant) . 



We selected four plants perfectly developed, and so sensi- 

 tive that the slightest contact, such as the friction of a fly's 

 wing, caused their leaves to shut up, and the petioles (leaf 

 stalks) to droop along their stems. Placing the pots contain- 

 ing these plants on an insulating stand, we attached to the 

 two ends of their stems a small copper wire in order to pass 

 through them the current from a single Bunsen's cell. After a 

 few seconds, when the plants reopened their leaves, and erected 



