OCR Text |
Show 58 DROSERA ROTUNDIFOLIA. CHAP. III. still contained did not undergo aggregation ~ny more than that which had exuded. In these spec1mens, as I may add, the individuality of the life of each c 11 was well illustrated. A full account will be given in the next chapter of the effects of heat on the leaves, and I nee l here only state that leaves immersed for a short time in water at a temperature of 120° Fahr. (48°·8 .Cent.), which, as. we have seen docs not immediately 1nduce aggregation, were then' placed in a few drops of_ a stro~g s_olntiou of one part of carbonate of ammon1a to 10.) of water, and became finely aggregated. On the other hand, leaves after an immersion in water at 1!JOo (G5o·G Cent.): on being placed in the same stron o· . sol n tion, did not undergo aggregation, th cells beeo~1ng filled with brownish, pulpy, or muddy matter. W1th leaves subjected to temperatul.·es b tween these two extr 1nes of 120° and 150° Fahr. ( 48°·8 and 65°·5 Cent.), therC' were gradations in the completeness. of the proc ~· ; the former temperature not preventing aggregat1o11 from the subsequent action of carbonate of ammonia, the latter quite stopping it. Thus, leaves immersed in water, heated to 130° (54°·4 C nt.), and then in the solution, formed perfectly defined spheres, but these were decidedly smaller than in ordinary cases. vVith other leaves heated to 140° (60° Cont.), the spheres were extremely small, yet well defined, but many of the cells contained, in addition, some brownish pulpy matter. In two cases of leaves heated to 145° (62°·7 Cent.), a few tentacles could be found with some of their cells containing a few minute spheres; whilst the other cells and other whole tentacles included· only the brownish, disintegrated. or pulpy matter. The fluid within the cells of the t n tacles must be in an oxygenated condition, in order that the force or CHAP. III. THE PROCESS OF AGGREGATION. 59 influence which induces aggregation should be transmitted at the proper rate from cell to cell. A plant, vi'ith its roots in water, was left for 45 m. in a vessel containing 122 oz. of carbonic acid. A leaf from this plant, and, for comparison, one from a fresh plant, were both immersed for 1 hr. in a rather strong solution of carbonate of ammonia. They were then compared, and certainly there was much less aggregation in the leaf which had been subjected to the carbonic acid than in the other. Another plant was exposed in the same vessel for 2 hrs. to carbonic acid, and one of its leaves was then placed in a solution of one part of the carbonate to 437 of water; the glands were instantly blackened, showing that they had absorbed, and that their contents were aggregated; but in the cells close beneath the glands there was no aggregation even after an interval of 3 hrs. After 4 hrs. 15m. a few minute spheres of protoplasm were formed . in these cells, but even after 5 hrs. 30 m. the aggregation did not extend down the pedicels for a length equal to that of the glands. After numberless trials with fresh leaves immersed in a solution of this strength, I have never seen the aggregating action transmitted at nearly so slow a rate. Another plant was left for 2 hrs. in carbonic acid, but was then exposed for 20 m. to the open air, during which time the leaves, being of a red colour, would have absorbed some oxygen. One of them, as well as a fresh leaf for comparison, were now im1nersed in the same solution as before. The former were looked at repeatedly, and after an interval of 65 m. a few spheres of protoplasm were first observed in the cells close beneath the glands, but only in two or three of the longer tentacles. After 3 hrs. the aggregation had travelled down the pedicels of a few of the tentacl~s |