| OCR Text |
Show 208 DROSERA ROTUNDIFOLIA. CHAP. IX. expanded. The tentacles were now examined, and the aggregated masses were almost wholly redissolved; the cells being filled with homogeneous pnrple fluid, with the exception here and there of a single globular mass. We thus see how completely the protoplasm bad escaped all injury from the poison. As the glands were soon rendered quite white, it occurred to me that their texture might have been modified in such a manner as to prevent the poison passing into the cells beneath, . and consequenHy that the protoplasm within these cells had not been at all affected. Accordingly I placed another leaf, which had been immersed for 48 hrs. in the poison and afterwards for 24 hrs. in water, in a little solution of one part of carbonate of ammonia to 218 of water; in 30m. the protoplasm in the cells beneath the glands became darker, and in the courfle of 24 hrs. the tentacles were filled down to their bases with dark-coloured spherical masses. Hence the glands had not lost thoir power of absorption, as far as the carbonate of ammonia is concerned. From these facts it is manifest that the poison of the cobra, though so deadly to animals, is not at all poisonous to Drosera; yet it causes strong and rapid inflection of the tentacles, and soon discharges all colour from the glands. It seems even to act as a stimulant to the protoplasm, for after considerable experience in observing the movements of this substance in Drosera, I have never seen it on any other occasion in so active a state. I was therefore anxious to learn how this poison affected animal protoplasm; and Dr. Fayrer was so kind as to make some observations for me, which he has since published.* Ciliated epithelium from the mouth of a frog was placed in a solution of ·03 gramme to 4·6 cubic em. of water ; others being placed at the same time in pure water for comparison. The movements of the cilia in the solution seemed at :first increased, but soon languished, and after between 15 and 20 minutes ceased; whilst those in the water were still acting vigorously. The white corpuscles of the blood of a frog, and the cilia on two infusorial animals, a Paramrecium and Volvox, were similarly affected by the poison. Dr. Fayrer also found that the muscle of a frog lost its irritability after an immersion of 20 m. in the solution, not then responding to a strong electrical current. On the other hand, the movements of the cilia on tho mantle of an Unio were not always arrested, even when left for a consider- * 'Proceedings of Royal Society,' Feb. 18, 1875. CHAP. IX. CAMPHOR. 209 able time in a very strong solution. On the whole, it seem8 that the poison of the cobra acts far more injuriously on the protoplasm of the higher animals than on that of Drosera. There is one other point which may be noticed. I have occasionally observed that the drops of secretion round the glands were rendered somewhat turbid by certain solutions, and more especially by some acids, a film being formed on the surfaces of the drops; but I never saw this effect produced in so conspicuous a manner as by the co bra poison. vVhen tho stronger solution was employed, the drops appeared in 10m. like little white rounded clouds. After 48 hrs. the secretion wn,s changed into threads and sheets of a membranous substance, including minute granules of various sizes. Camplwr.-Some scraped camphor was left for a day in a bottle with distilled water, and then filtered. A solution thus made is said to contain 10 1 00 of its weight of camphor; it smelt and tasted of this substance. Ten leaves were immersed in thi~ solution; after 15 m. five of them were well inflected, two showing a first trace of movement in 11 m. and 12 m. ; th ' sixth leaf did not begin to move until 15 m. had elapsed, but was fairly well inflected in 17 m. and quite closed in 24 m. ; the seventh began to move in 17 m., and was completely shut iu 26 m. The eighth, ninth, and tenth leaves were old and of a very dark reel colour, and these were not inflected after an immersion of 24 hrs.; so that in making experiments with camphor it is necessary to avoid such leaves. Some of these leaves, on being left in the solution for 4 hrs., became of a rather clingy pink colour, and secreted much mucus; although their tentacles were closely inflected, the protoplasm within the cells was not at all aggregated. On another occasion, however, after a longer immersion of 24 hrs., there was well marked aggregation. A solution made by adding two drops of camphorated spirits to an ounce of water did not act on one leaf; whereas thirty minims added to an ounce of water acted on two leaves immersed together. M. Vogel has shown* that the flowers of various plants do not wither so soon when their stems are placed in a solution of camphor as when in water; and that if n.lready slightly withered, they recover more quickly. The germination of certain seeds is also accelerated by the solution. So that camphor acts as [L stimulant, and it is the only known stimulant for plants. I * 'Gardener's Chronicle,' 1874, p. 671. Nearly similar observation~ were made in 1798 by B. S. Barton. p |
