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Show 84 DROSERA ROTUNDIFOLIA. CHAP. V. fact that water at this temperature extracts matter from them which excites Drosera to an extraordinary degree. Grasses co:ntain far less nitrogeE.OIUS :matter than do peas or cabbages. The leaves and st~l:ks of three common kinds were ehopped and boiled for some time in distilled water. Drops of this decoction (after having stood for 2.4 hrs.) were placed on six; leaves, and acted i:n a rather peculiar manner, of which other instances will be given in the seventh chapter on the salts of ammonia. After 2 hrs. 30 m. fonr of the leaves had their blades greatly inflected, but :not thei:r exterior tentacles ; and so it was with all six leaves after 24 hrs. Two days afterwards the blades,. as well as the few submarginal tentacles which had been inflected, all 1·e-expa:nded; and much of the fluid on their discs was by this time absa.rbed. It appea1·s that tho decoction strongly excites the glands on the dil:lc,. causing tho blade to· be quickly and greatly inflected; but that the stimulus, differently from what occurs in ordinary cases.~ does not spread, or 0'nly in a feehle degree, to the exterior tentacles. I may here add that one part of the ext1--act of belladonna (ptocured from a d1rnggist) was dissolved in 437 of water, and drops we:re placed on six leaves. Next day all six were somewhat inflected, and afte:r 48 h:rs. were completely rc-oxpanded. It was not the included atropine which produced this e±1'oct, for I subsequently ascertained that it is quite powerless. I also procured some extract of hyoscyrumus from three shop~, and made infusions of the same strength as before. Of these three infusions, only one acted on some of the leaves, which were tried. Though druggists believe that all the albumen is precipitated in the preparation of these drugs, I ca:nnot doubt that some is occasionally retained ; and a trace would be sufficient to excite the more sensitive leaves of Drosera. CuAP. VI. DIGESTION. 85 CHAPTER VI. THE DIGESTIVE POWER OF THE SECRETION OF DROSERA. The secretion rendered acid by the direct and indirect excitement of the glands-Nature of the acid-- Digestible substances_ Albumen, its digestion arrested by alkalies, recommences by the addition of an add- Meat- Fibrin- Syntonin- Areolar tissue_ Cartilage- Fibro-cartilage-Bone-Enamel and dentine- Phosphate of lime- INbrous basis of 1one- Gelatine- Chondrin_ Milk, caseiu and cheese- Gluten- Legumin- Pollen- Globulin - Hoomatin- Indigestible substances- Epidermic productions_ Fibro-elastic tissue- Mucin- Pepsin-Urea- Chi tine- Cellulose --:- Gun-cotton- Chlorophyll- Fat and oil- Starch- Action of the secretion on living seeds- Summary and concludin(J' remarks. b ~s we have seen that nitrogenous fluids act very drfferently on the leaves of Drosera from non-nitrogenous fluids, and as the leaves remain clasped for a much longer time over various organic bodies than over inorganic bodies, such as bits of glass, cinder, wood, &c., it becomes an interesting inquiry, whether they c~n only absorb matter already in solution, or render It· soluble,-that is, have the power of digestion. We shall immediately see that they certainly have this power, and that they act on albuminous compounds in exactly the same manner as does the gastric juice of mammals; ~he digested matter being afterwards absorbed. This fact, which will be clearly proved, is a wonderful one in the p4ysiology of plants. I wust here state ~hat I have been aided throughout all my lat~r expenments by many valuable suggestions and assistance given me with the greatest kindness by Dr. Burdon Sanderson. |