Qnar. XVI. SECRETION, ABSORPTION, DIGESTION. 381 
bearing on our subject, that when a plant is pulled 
up, the leaves immediately curl downwards so as 
almost to conceal the roots,—a fact which has been 
noticed by many persons. I suppose that this is due 
to the same tendency which causes the outer and older 
leaves to lie flat on the ground. It further appears 
that the flower-stalks are to a certain extent irritable, 
for Dr. Johnson states that they “bend backwards if 
rudely handled.” * 
Secretion, Absorption, and Digestion.—I will first give 
my observations and experiments, and then a summary 
of the results. 
The Effects of Objects containing Soluble Nitrogenous Matter. 
(1) Flies were placed on many leaves, and excited the glands 
to secrete copiously ; the secretion always becoming acid, though 
not so before. After a time these insects were rendered so 
tender that their limbs and bodies could be separated by a 
mere touch, owing no doubt to the digestion and disintegration 
of their muscles. The glands in contact with a small fly con- 
tinued to secrete for four days, and then became almost dry. 
A narrow strip of this leaf was. cut off, and the glands of the 
longer and shorter hairs, which had lain in contact for the 
four days with the fly, and those which had not touched it, 
were compared under the microscope and presented a won- 
derful contrast. Those which had been in contact were filled 
with brownish granular matter, the others with homogeneous 
fluid. There could therefore be no doubt that the former had’ 
absorbed matter from the fly. 
(2) Small bits of roast meat, placed on a leaf, always caused 
much acid secretion in the course of a few hours—in one case 
within 40 m. When thin fibres of meat were laid along the 
margin of a leaf which stood almost upright, the secretion ran 
down to the ground. Angular bits of meat, placed in little 
pools of the secretion near the margin, were in the course of 
* ‘English Botany,’ by Sir J. E. Smith; with colourea tigures by 
J. Sowerby ; edit. of 1832; tab. 24, 25, 26. 
