OCR Text |
Show 326 ALDROV ANDA VESICULOSA. CHAP. XIV. already soluble animal matter. The included water would thus be pressed out, and the secretion consequently not be too much diluted to act. With respect to the quadrifid processes on the outer parts of the lobes, I was not able to decide whether they had been acted on by the infusion ; for the lining of protoplasm was somewhat shrunk before they were immersed. Many of the points on the infolded rims also had their lining of protoplasm similarly shrunk, and contained spherical granules of hyaline matter. A solution of urea was next employed. This substance was chosen partly because it is absorbed by the q uadrifid processes and more especially by the glands of Utricularia-a plant which, as we shall hereafter see, feeds on decayed animal matter. As urea is one of the last products of the chemical changes going on in the living body, it seems fitted to represent the early stages of the decay of the dead body. I was also led to try urea from a curious little fact mentioned by Prof. Cohn, namely that when rather large crustaceans are caught between the closing lobes, they are pressed so hard whilst making their escape that they often void their sausage-shaped masses of excrement, which were found within most of the leaves. These masses, no doubt, contain urea. They would be left either on the broad outer surfaces of the lobes where the quad- . rifids are situated, or within the closed concavity. In the latter case, water charged with excrementitious and decaying matter would be slowly forced outwards, and would bathe the quadrifids, if I am right in believing that the concave lobes contract after a time like those of Dionrea. Foul water would also be apt to ooze out at all times, especially when bubbles of air were generated within the concavity. A leaf was cut open and examined, and the outer CHAP. XIV. ALDROV ANDA VESICULOSA: 327 cells of the glands were found to contain only limpid fluid. Some of the quaclrifids included a few spherical granules, but several were transparent and empty, and their positions were marked. This leaf was now immersed in a little solution of one part of urea to 146 of water, or three grains to the ounce. After 3 hrs. 40 m. there was no change either in the glands or q uadri:fids ; nor was there any certain change in the glands after 24 hrs. ; so that, as far as one trial goes, urea does not act on them in the same manner as an infusion of raw meat. It was different with the quadri:fids ; for the lining of protoplasm, instead of presenting a uniform texture, was now slightly shrunk, and exhibited in many places minute, thickened, irregular, yellowish specks and ridges, exactly like those which appear within the q uadri:fids of U tricularia when treated with this same solution. Moreover, several of the quadri:fids, which were before empty, now contained moderately sized or very small, more or less aggregated, globules of yellowish matter, as likewise occurs under the same circumstances with U tricularia. Some of the points on the infolded margins of the lobes were similarly affected; for their lining of protoplasm was a little shrunk and included yellowish specks; and those which were before empty now contained small spheres and irregular masses of hyaline matter, more or less aggregated; so that both the points on the margins and the quadri:fids had absorbed matter from the solution in the course of 24 hrs.; but to this subject I shall recur. In another rather old leaf, to which nothing had been given, but which had been kept in foul water, some of the quadri:fids contained aggregated translucent globules. These were not acted on by a solution of one part of carbonate of ammonia to 218 of water ; and this negative result |