64 DROSERA ROTUNDIFOLIA. [Caar. ¥. 
CHAPTER V. 
Tur EFFEcTs OF NON-NITROGENOUS AND NITROGENOUS ORGANIC FLUIDS. 
ON THE LEAVES. 
Non-nitrogenous fluids—Solutions of gum arabic—Sugar—Starch—Diluted 
alcohol—Olive oil—Infusion and decoction of tea—Nitrogenous fluids— 
Milk—Urine—Liquid albumen—Infusion of raw meat—Impure mucus— 
Saliva—Solution of isinglass—Difference in the action of these two sets 
of fluids—Decoction of green peas—Decoction and infusion of cabbage— 
Decoction of grass leaves. 
Wuen, in 1860, I first observed Drosera, and was led to 
believe that the leaves absorbed nutritious matter from the 
insects which they captured, it seemed to me a good plan 
to make some preliminary trials with a few common fluids, 
containing and not containing nitrogenous matter: and the 
results are worth giving. 
In all the following cases a drop was allowed to fall from 
the same pointed instrument on the centre of the leaf; and 
by repeated trials one of these drops was ascertained to be on 
an average very nearly half a minim, or 51, of a fluid ounce, 
or +0295 ce. But these measurements obviously do not. 
pretend to any strict accuracy; moreover, the drops of the 
viscid fluids were plainly larger than those of water. Only 
one leaf on the same plant was tried, and the plants were 
collected from two distant localities. The experiments were 
made during August and September. In judging of the 
effects, one caution is necessary: if a drop of any adhesive 
fluid is placed on an old or feeble leaf, the glands of which 
have ceased to secrete copiously, the drop sometimes dries up, 
especially if the plant is kept in a room, and some of the 
central and submarginal tentacles are thus drawn together, 
giving to them the false appearance of having become 
inflected. This sometimes occurs with water, as it is rendered 
adhesive by mingling with the viscid secretion. Hence the 
only safe criterion, and to this alone I have trusted, is the 
bending inwards of the exterior tentacles, which have not 
been touched by the fluid, or at most only at their bases. In 
