OCR Text |
Show 194 DROSERA ROTUNDIFOLIA. CHAr. VIII. there was no inflection; after 7 hrs. 30 m. two of tho loaves showed some inflection, and the glands were almost white; after 21 hrs. two of the leaves were considerably inflected, and a third slightly; most of the glands were white, the others dark red. After 45 hrs. one leaf had almost every tentacle inflected · a second a large number ; the third and fourth very few ; almost 'an the glands were white, excepting those on tho discs of two of the leaves, and many of these were very dark rod. The leaves appeared dead. Hence lactic acid a.cts ~n a very peculiar manner causing inflection at an extraordinanly slow Tate, and being highly pojsonous. Immersion in even weaker s~lutions, viz. of one part to 1312 and 1~50 of ~ater, apparently killed the leaves (the tentacles after a time being b_owed ?ackwards), and rendered the glands white, but caused no InflectiOn. (Jallic Tannic, Tartaric, and Citric Acids.-One part to 437 of water. 'Three or four leaves were immersed, each in thirty minims of these four solutions, so that each leaf received -f-6 of a grain, or 4·048 mg. No infl?c~ion wa~ caused iJ?- 24 hTs., and tl:e leaves did not appear at all InJured. rhose whiCh had been m the tannic and tartaric acids were placed in a solution (1 gr. to 20 oz.) of phosphate of ammonia, but no inflection ensued in 24 hrs. On the other hand, the four ]eaves which had been in the citric acid, when treated with tho phosphate, became decidedly inflected in 50 m. and strongly inflected after 5 l1rs., and so remained for the next 24 hrs. Mulic Add.-Three leaves were immersed in ninety minims of a solution of one part to 437 of water; no inflection was caused in 8 hrs. 20m., but after 24 hrs. two of them were considerably, and the third slightly, inflected-more so than could be accounted for by the action of water. No great amount of mucus was secreted. They were then placed in water, and after two flays partially re-expanded. Hence this acid .is n?t poi o.n?us. Oxalic Acid.-Three leaves were immersed In ninety mmims of a solution of 1 gr. to 437 of water; after 2 hrs. 10 m. there was much inflection; glands pale; tho surrounding fluid of a dark pink colour; after 8 hrs. excessive inflection. The ]eaves were then placed in water; after about 16 hrs. the te~tacles ~ere .of a very dark red colour, like those of the leaves In acebc aCI~. After 24 additional hours, the three leaves were dead and then glands colourless. . . Benzoic .Ar;id.-Five leaves were immersed, each m thu·ty minims of a solution of 1 gr. to 437 of water. 'fhis solution was so weak that it only just tasted acid, yet, as we shall see, :was highly poisonous to Drosera. After 52 m. the submargmal CHAP. VIII. THE EFFECTS OF ACID 195 tentacles .were somewhat ~nflectecl, and all the glands very palecolou~ ed' the ~urrounding fluid was coloured pink. On one occasiOn the·flm~ became pink in the course of only 12m., and the glands as white as if the leaf had boon dipped in boilinc,. water. After_ 4 hrs. much inflection; but none of the tentacle~ were closely mflectecl, owing, as I believe, to their havincr been paralysed b~fore they had time to complete their mov~ment. An extraordmar~ quantity of mucus was secreted. Some of tho leaves were left In the solution; others, after an immersion of 6 hrs. 3.0 m., were placed in water. Next morning both lots ~ere quito dead; the leaves in the solution being flaccid, tho~e In the water (now coloured yellow) of a pale brown tint and their glands white. ' Succin'i.c .Ac'id.-Throe leaves were immersed in ninety minims of a solutwn of 1 gr. to 437 of water; after 4 hrs. 15 m. considerable and. after 23 hrs. great inflection; many of the glands pale; fl~1d coloured pink. The leaves were then washed and placed In water; after two days there was some re-oxpansion, but many of the glands were still white. This ncid is not nearly so poisonous as oxalic or benzoic. Ur~c Acid.-Three leaves were immersed in 180 minims of a s~lutwn of 1 gr. to 875 of warm water, but all the acid. was not dissolved; so that each received nearly 1\, of a grain. After 25 m. there was some slight inflection, but this never increased ; after 9 hrs. the glands were not discoloured, nor was the solution coloured pink; nevertheless much mucus was secreted. The leaves were then placed in water, and by next morning ~ully ~e-expanded .. I doubt whether this a.cid really cau · u~ 1nflectwn, for the slight movement which at first occunecl may lmve ?een due to the presence of a trace of albuminous matter. But It produces some effect, as shown by the secretion of Ro much mucus. Hippuric Acid.-Four leaves were immersed in 120 minims of a solution of 1 gr. to 437 of water. After 2 hrs. the fluid was coloured pink; glands pale, but no inflection. After 6 hrs. some inflection; after 9 hrs. all four leaves great.Jy inflected; much mucus secreted; all the glands very pale. The leaves were then le~·t in :vater for two days; they remained closely inflected, With thmr glands colourless, and I do not doubt were killed. .li_Yd'l·ocyanic Acid.-Four lea;,ves were immersed, each in thirty minims of one part to 437 of water; in 2 hrs. 45 m. all tho tentacles were considerably inflected, with many of the glands pale ; after 3 hrs. 45 m. all strongly inflected, and tho surroundIng fluid coloured pink; after 6 hrs. all closely inflected. After 0 ~ |