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Show 94 DROSERA ROTUNDIFOLIA. CHAP. VI. ·ned after 21 hrs. 30 m., and all four leaf. These were examlfter 46 hrs. the two cubes on the one were found rounded. . fi d the fluid being perfectly transleaf were completely hqu~ e ' e opaque white streaks could parent; on the other .lea s~~h fluid. After 72 hrs. these still be seen in the midst t~ere ~as still a little viscid fluid streaks disaap·p eared, but .t was almost all absorbed on the left on the 1sc; wh ereas 1 w beginning to re-expan d . first leaf. Both leaves were no . The best an d a1 m os t sole test of the presence · of 1 to pepsin in the secretion some ferment ana ogouts lise tho acid of the secretion ·ed to be to neu ra a~pear r and to observe whether the proce.ss w1tb an ~lka I, d. d then to add a little acul 0 f digestion cease ' an d Th. h th the process recommence . IS and observe 'd!V e ere shall see with success, but it was done, an ' as w ' 1 · ts · ( ar first to try two con tro expenm n '. was n1e cessh eyth er the a dd1't .I on of minute drops of namt e. Yo' f wth e same si.z e as those of the dis so.l vecl walak aelri es to be used wou ld s t op t.h e process of digc·s]-~ ti.o n . and, secon dl y' wh ether minute dropsd of . wo,t \_ hydr'o chlon.c ac1. d ' 0 f the some strength an sizeT ha s those to b e use d ' would inJ· ure th. e .l eav.e· s._, ._ e .{! two 101 1 ow1. n g experiments were therefore tneu. . Small cubes of albumen were put on three Expen~ent.6~te drops of distilled water on the head of a pin ]ea:es, dand dm;~ro or three times daily. These did not in the were a e 48 b th bes were comleast l de~! t~e ~r~~s:h f~r~~tefeaves.rs.On ethc: third day tl~c plelaevtee sy be gISaSnO vtoe re-expand ' and on the fourth day all the fluid was absorbed. f lbumen were put on two E xpe'rimeu t 7. -Small cubes o a . . t crth f leaves and minute drops of hydrochlonc aCid, of the. s reno , ~ ' 437 of water were added two or three times. 'Ihis J~d ~~t i~ the least delay, but seemed rather to hasten, th~ f dl.gesti· on . for every trace of the albumen disa ppeare p. roc2e4:s sh ol' 30 m 'A fter three days the leaves pal· t· 11 · re- Ia y . In d ;· nd b; this time almost all the viscid fluid on theu ~~~:n :a~ aabsorbed. It is almost superfluous to state that CHAP. VI. DIGESTION. 95 cubes of albumen of the same size as those above used, left for seven days in a little hydrochloric acid of the above strength, retained all their angles as perfect as ever. Experiment 8.-Cubes of albumen (of ~~ of an inch, or 2·54 rom.) were placed on five leaves, and minute drops of a solution of one part of carbonate of soda to 437 of water were added at intervals to three of them, and drops of carbonate of potash of the same strength to the other two. The drops were given on the head of a rather large pinJ and I ascertained that each was equal to about 1 1 0 of a minim ("0059 ml.)J so that each contained only 48 1 00 of a grain ("0135 mg.) of the alkali. This was not sufficient) for after 46 hrs. all five cubes were dissolved. Experiment 9.-The last experiment was repeated on four leaves, with this difference, that drops of the same solution of carbonate of soda were added rather oftener, as often as the secretion became acid, so that it was much more effectually neutralised. And now after 24 hrs. the angles of three of the cubes were not in the least rounded, those of the fourth being so in a very slight degree. Drops of extremely weak hydrochloric acid (viz. one part to 84 7 of water) were then added, just enough to neutralise the alkali which was still present; and now digestion immediately recommenced) so that after 23 hrs. 30 m. three of the cubes were completely dissulvedJ whilst the fourth was converted into a minute sphere) surrounded by transparent fluid; and thi~ sphc~re next day disappeared. ExpeTiment 10.-Stronger solutions of carbonate of soda and of potash were next used, viz. one part to 109 of water; and as tbe same-sized drops were given as before, each drop contained 1 / 00 of a grain ('0539 mg.) of either salt. Two cubes of albumen (each about 4~ of an inchJ Ol' ·635 mm.) were placed on the same leaf, and two on another. Each leaf received, as soon as the secretion became slightly acid (and this occurred four times within 24 hrs. ), drops either of the soda or potash, and the acid was thus effectually neutralised. The experiment now succeeded perfectly, for after 22 hrs. the angles of the eubes were as sharp as they were at first, and we know from experiment 5 that such small.cubes would have been completely rounded within this time by the secretion in its natural state. Some of the :fluid was now removed with blotting-paper from tbe discs of the leaves, and minute drops of hydrochloric acid of tbe strength of one part to 200 of water was added. Acid of this greater strength was used as tho solutions of the alkalies were stl·onger. The |