298 DION.EA MUSCIPULA. CHAP. X HI. 



the surface of the leaf much more sensitive to a touch 

 than it is in its ordinary state ; and this is a curious 

 fact. Two days afterwards the end of the leaf where 

 nothing had been placed began to open, and on the 

 third day was much more open than the opposite end 

 where the albumen had lain. 



Lastly, large drops of a solution of one part of car- 

 bonate of ammonia to 146 of water were placed on 

 some leaves, but no immediate movement ensued. I 

 did not then know of the slow movement caused by 

 animal matter, otherwise I should have observed the 

 leaves for a longer time, and they would probably 

 have been found closed, though the solution (judging 

 from Drosera) was, perhaps, too strong. 



From the foregoing cases it is certain that bits of 

 meat and albumen, if at all damp, excite not only the 

 glands to secrete, but the lobes to close. This move- 

 ment is widely different from the rapid closure caused 

 by one of the filaments being touched. We shall see 

 its importance when we treat of the manner in which 

 insects are captured. There is a great contrast be- 

 tween Drosera and Dionoea in the effects produced by 

 mechanical irritation on the one hand, and the absorp- 

 tion of animal matter on the other. Particles of glass 

 placed on the glands of the exterior tentacles of Dro- 

 sera excite movement within nearly the same time, 

 as do particles of meat, the latter being rather the 

 most efficient ; but when the glands of the disc have 

 bits of meat given them, they transmit a motor impulse 

 to the exterior tentacles much more quickly than do 

 these glands when bearing inorganic particles, or 

 when irritated by repeated touches. On the other 

 hand, with Dioneea, touching the filaments excites 

 incomparably quicker movement than the absorption 

 of animal matter by the glands. Nevertheless, in 



