To ascertain whether these leaves had been at all injured, bits of meat were placed on them, and after 24 hrs. No inflection ensued in the course of 48 hrs. I am surprised at this fact, as I believe that the starch of commerce generally contains a trace of gluten, and this nitrogenous substance causes inflection, as we shall see in the next chapter.Īlcohol, Diluted.―One part of alcohol was added to seven of water, and the usual drops were placed on the discs of three leaves. Starch.―A mixture about as thick as cream was dropped on six leaves and left on them for 30 hrs., no effect being produced. Sugar.―Drops of a solution of white sugar of three strengths (the weakest containing one part of sugar to 73 of water) were left on fourteen leaves from 32 hrs. It is necessary to try pure gum arable, for a friend tried a solution bought ready prepared^and this caused the tentacles to bend but he afterwards ascertained that it contained much animal matter, probably glue. These were tried on fourteen leaves the drops being left on the discs from 24 hrs. Gum arabic.―Solutions of four degrees of strength were made one of six grains to the ounce of water (one part to 73) a second rather stronger, yet very thin a third moderately thick, and a fourth so thick that it would only just drop from a pointed instrument. The leaves would have been excited into movement by every Produce no effect might have been anticipated, as otherwise Getting the leaves into a proper position. Nevertheless, in some other and rare cases, a few tentaclesīecame for a short time inflected but this may have beenĬaused by the glands having been accidentally touched in Trial, drops of distilled water were placed on between thirtyĪnd forty leaves, and no effect whatever was produced Mere drying up of an adhesive fluid and the consequentįirst for the non-nitrogenous fluids. This latter movement is never caused, as far as I have seen, by the When an insect or bit of meat is placed on the disc. Leaf likewise often curves inwards, in the same manner as Having been stimulated by the fluid, and transmitting a In this case the movement is wholly due to the central glands Not been touched by the fluid, or at most only at their bases. The bending inwards of the exterior tentacles, which have The only safe criterion, and to this alone I have trusted, is This sometimes occurs with water, as it is renderedĪdhesive by mingling with the viscid secretion. Giving to them the false appearance of having become Of the central and submarginal tentacles are thus drawn together, Which have ceased to secrete copiously, the drop sometimesĭries up, especially if the plant is kept in a room, and some The effects, one caution is necessary: if a drop of any adhesiveįluid is placed on an old or feeble leaf, the glands of Were collected from two distant localities. Only one leaf on the same plant was tried, and the plants The viscid fluids were plainly larger than those of water. Not pretend to any strict accuracy moreover, the drops of On an average very nearly half a minim, or 1 960 of a fluid The same pointed instrument on the centre of the leaf andīy repeated trials one of these drops was ascertained to be In all the following cases a drop was allowed to fall from Make some preliminary trials with a few common fluids,Ĭontaining and not containing nitrogenous matter: and the Which they captured, it seemed to me a good plan to W hen, in 1860, I first observed Drosera, and was led toīelieve that the leaves absorbed nutritious matter from insects 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. Non-nitrogenous fluids―Solutions of gum arabic―Sugar―Starch―Diluted alcohol―Olive oil―Infusion and decotion of tea―Nitrogenous fluids―Milk―Urine―Liquid albumen―Infusion of raw meat―Impure
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