ON THE IRRITABILITY OF THE BARBERRY, 3)5 



Bonnet's opinion is quite in opposition to Dr. Smith's; for Bonnet's opi- 

 he thinks, that tlie movement of the stamina of the bar- "'°^- 

 berry so much resembles the motion of a spring which un- 

 bends itself, that it cannot be attributed to irntability: an 

 opinion certainly thut requires only the evidence of seeing 

 the experiment performed, to refute it entirely. Would 

 even tlie most elastic spring, formed like the stamina of 

 the barberry, and like them also simply fixed by one end 

 (as if one end of the spring were nailed to a board, and not 

 fixed by any other mechanical contrivance) move w^hen 

 merely touched gently at a particular part of the fixed end? 

 certainly not. It may be observed indeed, that, if the loose 

 end of the spring were touched gently, a vibratory motion 

 would be produced ; but this motion is very different from 

 the gradual and steady movt irent of the stamiua of the bar- 

 berry. — Why then employ such an hypothesis, to account 

 for their motions ? 



Sennebier, when treating of the barberry, speaks thus: Sennebicr's 

 *« It has not yet been proved, that the movement of the ''^"^"^^ **" '^* 

 staminais accompanied with the contraction of the filaments, 

 which nevertheless was the first proof necessary to have 

 been given, in order to ascertain their irritability ; it is not 

 yet even well known, which is the irritable part of the fila- 

 ments, and whether it be only their base, as Smith has had 

 the address to discover." How Sennebier came to express 

 himself in this ambiguous manner is to me a matter of 

 surprise. — Indeed the different parts of this sentence seem 

 to contradict each other. 



Dr. Smith, as we have seen, has stated in a very perspi- 

 cuous and definite manner, that the inside of the base of 

 the filament possesses a high degree of irritability; and 

 his experiment, which I have quoted, shows evidently,, that 

 this part only is irritable. He has said also, that one side 

 of the filament becomes shorter than the other. Why then 

 is it stated by Sennebier, that we even do not well know 

 which is the irritable part of the filaments, and whether it 

 be only their base, as Smith has had the address to discover? 

 Why does Sennebier confess, that Smith has had the ad- 

 dress to discover, that the base of the filament only is irri- 

 table, immediately after he has asserted, that we are igno- 



rant 



