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Show 336 DROSOPHYLLUM LUSITANICUM. CHAP. XV. secretion was accumulated in the course of a day that it ran down the tentacles and covered large spaces of the leaves. The glands to which the above nained nitrogenous substances and liquids were given did not, as just stated, secret: more copiously; on .the c_ontrary, they absorbed then own drops of secretion with surprising quickness. Bits of damp fibrin were placed on :five glands, and when they were looked at after an interval of 1 hr. 12 m., the fibrin was almost dry, the secretion having been all absorbed. So it was .with three cubes of albumen after 1 hr. 19m., and with four other cubes, though these latter were not looked at until 2 hrs. 15 m. had elapsed. The same result followed in between 1 hr. 15m. and 1 hr. 30m. when particles both of cartilage and meat were placed on several glands. ~astly, a minute drop ~about !"/o of a Ininim) of a solution of one part of nitrate of ammonia to 146 of water was distributed between the secretion surrounding three glands, so that the ainount of fluid surrounding each was slightly increased; yet when loo1red at after 2 hrs., all three were dry. On the other hand, seven particles of glass and three of coalcinders, of nearly the same size as those of the above nained organic substances, were placed on ten glands; some of them being observed for 18 hrs., and others for two or three days; but there was not the least sign of the secretion being absorbed. Hence, in the fonner cases, the absorption of the secretion n1ust have been due to the presence of some nitroo·enous matter, which was either already soluble or w:s rendered so by the secretion. As the :fibrin was pure, and had been well washed in distilled water after being kept in glycerine, and as the cartilage had been soaked in water, I suspect that these substances must CHAP. XV. ABSORPTION. 337 have been slightly acted on and rendered soluble within the above stated short periods. The glands have not only the power of rapid absorp~ tl.on, but likewise of secreting again quickly; anJ this latter habit has perhaps been gained, inasmuch as insects, if they touch the glands, generally withdraw the drops of secretion, which have to be restored. The exact period of re-secretion was recorded in onJy a few cases. The glands on which bits of meat were placed, and which were nearly dry after about 1 hr. 30 m., when looked ~t after 22 additional hours, were found secreting; so It was after 24 hrs. with one gland on which a bit of .albumen. had been placed. The three glands ·to which a minute drop of a solution of nitrate of ammonia was d~str~buted, ·and which became dry after 2 hrs., were beginning to re-secrete after only 12 additional hours. Tentacles Incapable of Movement.-Many of the tall tentacles, with insects adhering to them, were care~ fully observed; and fragments of insects, bits of raw meat, albumen, &c., drops of a solution of two salts of ammonia and of saliva, were placed on the glands of many tentacles; but not a trace of movement could ever be .detected. I also repeatedly irritated the glands w1th a needle, and scratched and pricked the blades, but neither the blade nor the tentacles became at all inflected. "r e may therefore conclude that they are incapable of movement. On the Power of Absorption possessed by the Glands.! t has . already been indirect! y shown that the glands on ·pedicels absorb animal matter; and this is further shown by their changed colour and by the agoTeo·ation 0 f h . ' 0 b . t 81~ ·contents, after they have been left in contact With nitrogenous substances or liquids. The followino· ob serva tI' ons apply both to the glands supported ouu z |