. XIII. SECRETION AND ABSOEPTION. 299 



certain cases, this latter stimulus is the more powerful 

 of the two. Oil three occasions leaves were found 

 which from some cause were torpid, so that their lobes 

 closed only slightly, however much their filaments 

 were irritated ; but on inserting crushed insects 

 between the lobes, they became in a day closely shut. 

 The facts just given plainly show that the glands 

 have the power of absorption, for otherwise it is im- 

 possible that the leaves should be so differently af- 

 fected by non-nitrogenous and nitrogenous bodies, and 

 between these latter in a dry and damp condition. It 

 is surprising how slightly damp a bit of meat or albu- 

 men need be in order to excite secretion and afterwards 

 slow movement, and equally surprising how minute a 

 quantity of animal matter, when absorbed, suffices to 

 produce these two effects. It seems hardly credible, 

 and yet it is certainly a fact, that a bit of hard-boiled 

 white of egg, first thoroughly dried, then soaked 

 for some minutes in water and rolled on blotting 

 paper, should yield in a few hours enough animal 

 matter to the glands to cause them to secrete, and 

 afterwards the lobes to close. That the glands have 

 the power of absorption is likewise shown by the very 

 different lengths of time (as we shall presently see) 

 during which the lobes remain closed over insects and 

 other bodies yielding soluble nitrogenous matter, and 

 over such as do not yield any. But there is direct 

 evidence of absorption in the condition of the glands 

 which have remained for some time in contact with 

 animal matter. Thus bits of meat and crushed insects 

 were several times placed on glands, and these were 

 compared after some hours with other glands from 

 distant parts of the same leaf. The latter showed 

 not a trace of aggregation, whereas those which 

 had been in contact with the animal matter wcro 



