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Show 38 DROSERA ROTUNDIFOLIA. 0HAP. III. CHAPTER III. N O .F THE PROTOPLASM WITHIN TilE CELLS OF THE AGGREGATIO TENTACLES. Nature of the con tents of the cells before aggregation- V.a r. iou. s causes wh 1. c h ex c1'te aggregation -The process comm. enc. e w1thm the lands and travels down the tentacles-Descnptwn of the g t d ses and of their spontaneous movements-Currents afggregta el masalong the walls of the cells- Action of carbonate 0 pro op asm 1 · h fl 1 of ammom· a-'rhe g1·an· ules in the protoplasm w .n c ows a ong th ll coalesce with the central masse - Mmuteness of the e wa s . t· A t" quantity of carbonate of ammonia causmg aggrcga 10n -:- f{c ·1~n of other salts of ammonia - Of oth~r su~stancc , orgamc m s, & -Of water-Of heat-Redissolutwn of the ag(Yrcgated masses ~Proximate causes of the aggregation of the protopla ~Summary and concluding remarks-Supplementary ou · rvat10ns on aggregation in the roots of plants. I WILL here interrupt my account of the movements of the leaves, and describe the phenom non of aggregation, to which subject I hav alr ady alluded. If the tentacles of a young, yet fully matur cl 1 af, that has never been excited or become infloctecl, be exa1nined, the cells forming the p die ls are seen to be filled with homogeneous, purpl fluid. The walls are lined by a layer of colourless, circulating pr.ot?plasm; but this can be seen with 1nuch gr ater distinctness after the process of aggregation has been partly effected than before. The purple fluid which exudes from a crushed tentacle is somewhat coherent, and does not mingle with the surrounding water; it co~tains 1nuch flocculent or granular matter. But this 1natter may have been generated by the cells hav~ng been crushed; some degree of aggregation having l)een thus almost instantly caused. • CHAP. III. THE PROCESS OF AGGREGATION. 39 If a tentacle is examined some hours after the 1 d h b . d gan as .e en excite . by rep. eated touches, or b y an I·n - organic or organic particle placed on it or b th b . f . ' y e a sorption o certain fluids, it presents a wholly c~anged appearance. The cells, instead of being filled with homogeneous purple fluid, now contain variously shaped masses of purple matter, suspended in a colourless ~r almost colourless fluid. The change is so conspicuous that it is visible through a weak lens and even sometimes by the naked eye ; the tentacle~ now have a mottled appearance, so that one thus affected ~an be picked out with ease fron1 all the o~hers. . r~e sam~ result follows if the glands on the disc are Irntated In any manner, so that the exterior tentacles become inflected; for their contents will the~ be found in an aggregated condition, although theu g~a~ds have not as yet touched any object. But aggregation may occur independently of inflection, as we shall presently see. By whatever cause the process may have been excited, it commences within the glands, and then travels down the tentacles. It can be observe~ much more distinctly in the upper cells of the pedicels than within the glands, as these are somewhat opaque. Shortly after the tentacles have re-~xpanded, the little masses of protoplasm are all redissolved, and the purple fluid within the cells becomes as homogeneous and transparent as it was at first. The process of redissolution travels upwards from the .bases of the tentacles to the glands, and the~efore In a reversed direction to that of aggregation. Tentacles in an aggregated condition were shown to Prof. Huxley, Dr. Hooker, and Dr. Burdon S~nderson, who observed the changes under the microscope, and were much struck with the whole phenomenon. |