CHAP. XVI. MOVEMENTS OF THE LEAVES. 377 



there was a trace of movement in 1 hr. or 1 hr. 30 in. 

 The pressure from fragments of glass- excites move- 

 ment almost as quickly as the absorption of nitro- 

 genous matter, but the degree of incurvation thus 

 caused is much less. After a leaf has become well 

 incurved and has again expanded, it will not soon 

 answer to a fresh stimulus. The margin was affected 

 longitudinally, upwards or downwards, for a distance of 

 13 of an inch (3*302 mm.) from an excited point, but 

 for a distance of '46 of an inch between two excited 

 points, and transversely for a distance of '2 of an 

 inch (5*08 mm.). The motor impulse is not accom- 

 panied, as in the case of Drosera, by any influence 

 causing increased secretion; for when a single gland 

 was strongly stimulated and secreted copiously, the 

 surrounding glands were not in the least affected. 

 The incurvation of the margin is independent of in- 

 creased secretion, for fragments of glass cause little 

 or no secretion, and yet excite movement ; whereas 

 a strong solution of carbonate of ammonia quickly 

 excites copious secretion, but no movement. 



One of the most curious facts with respect to the 

 movement of the leaves is the short time during which 

 they remain incurved, although the exciting object is 

 left on them. In the majority of cases there was well- 

 marked re-expansion within 24 hrs. from the time 

 when even large pieces of meat, &c., were placed on 

 the leaves, and in all cases within 48 hrs. In one 

 instance the margin of a leaf remained for 32 hrs. 

 closely inflected round thin fibres of meat ; in another 

 instance, when a bit of sponge, soaked in a strong in- 

 fusion }f raw meat, had been applied to a leaf, the 

 margin began to unfold in 35 hrs. Fragments of glass 

 Veep the margin incurved for a shorter time than do 

 nitrogenous bodies ; for in the former case there 



