Insectivorous Plants

44

Binz found several years ago (as stated in 'The Journal of Anatomy and Phys.' November 1872, p. 195) that quinia is an energetic poison to low vegetable and animal organisms. Even one part added to 4000 parts of blood arrests the movements of the white corpuscles, which become "rounded and granular." In the tentacles of Drosera the aggregated masses of protoplasm, which appeared killed by the quinine, likewise presented a granular appearance. A similar appearance is caused by very hot water.

45

Dr. Fayrer, 'The Thanatophidia of India,' 1872, p. 150.

46

'Proceedings of Royal Society,' Feb. 18, 1875.

47

'Gardener's Chronicle,' 1874, p. 671. Nearly similar observations were made in 1798 by B. S. Barton.

48

See Dr. M. Traube's curious experiments on the production of artificial cells, and on their permeability to various salts, described in his papers: "Experimente zur Theorie der Zellenbildung und Endosmose," Breslau, 1866; and "Experimente zur physicalischen Erklrung der Bildung der Zellhaut, ihres Wachsthums durch Intussusception," Breslau, 1874. These researches perhaps explain my results. Dr. Traube commonly employed as a membrane the precipitate formed when tannic acid comes into contact with a solution of gelatine. By allowing a precipitation of sulphate of barium to take place at the same time, the membrane becomes "infiltrated" with this salt; and in consequence of the intercalation of molecules of sulphate of barium among those of the gelatine precipitate, the molecular interstices in the membrane are made smaller. In this altered condition, the membrane no longer allows the passage through it of either sulphate of ammonia or nitrate of barium, though it retains its permeability for water and chloride of ammonia.

49

Dr. Fayrer, 'The Thanatophidia of India,' 1872, p. 4.

50

Sachs, 'Trait de Bot.' 1874, pp. 846, 1037.

51

'Bot. Zeitung,' 1860, p. 234.

52

'Bot. Zeitung.' 1860, p. 437.

53

'Bot. Zeitung,' 1860, p. 240.

54

M. Ziegler made similar experiments by cutting the spiral vessels of Drosera intermedia('Comptes rendus,' 1874, p. 1417), but arrived at conclusions widely different from mine.

55

'Videnskabelige Meddelelser de la Soc. d'Hist. nat. de Copenhague,' Nos. 10-12, 1872, woodcuts iv. and v.

56

Sachs, 'Trait de Bot.' 3rd edit. 1874, p. 1038. This view was, I believe, first suggested by Lamarck. Sachs, ibid. p. 919.

57

'Abhand. der Schles. Gesell. fr vaterl. Cultur,' 1861, Heft i. An excellent abstract of this paper is given in the 'Annals and Mag. of Nat. Hist.' 3rd series, 1863, vol. xi. pp. 188-197.

58

Mrs. Treat has given an excellent account in 'The American Naturalist,' December 1873, p. 705, of Drosera longifolia (which is a synonym in part of Drosera anglica), of Drosera rotundifolia and filiformis.

59

'American Naturalist,' December 1873, page 705.

60

'Gardener's Chronicle,' 1874, p. 209.

61

Dr. Hooker, in his address to the British Association at Belfast, 1874, has given so full an historical account of the observations which have been published on the habits of this plant, that it would be superfluous on my part to repeat them.

'Gardener's Chronicle,' 1874, p. 464.

62

Dr. W.M. Canby, of Wilmington, to whom I am much indebted for information regarding Dionaea in its native home, has published in the 'Gardener's Monthly,' Philadelphia, August 1868, some interesting observations. He ascertained that the secretion digests animal matter, such as the contents of insects, bits of meat, &c.; and that the secretion is reabsorbed. He was also well aware that the lobes remain closed for a much longer time when in contact with animal matter than when made to shut by a mere touch, or over objects not yielding soluble nutriment; and that in these latter cases the glands do not secrete. The Rev. Dr. Curtis first observed ('Boston Journal Nat. Hist.' vol. i., p. 123) the secretion from the glands. I may here add that a gardener, Mr. Knight, is said (Kirby and Spencer's 'Introduction to Entomology,' 1818, vol. i., p. 295) to have found that a plant of the Dionaea, on the leaves of which "he laid fine filaments of raw beef, was much more luxuriant in its growth than others not so treated."

63

According to Dr. Curtis, in 'Boston Journal of Nat. Hist,' vol. i 1837, p. 123.

64

Dr. Canby remarks ('Gardener's Monthly,' August 1868), "as a general thing beetles and insects of that kind, though always killed, seem to be too hard-shelled to serve as food, and after a short time are rejected." I am surprised at this statement, at least with respect to such beetles as elaters, for the five which I examined were in an extremely fragile and empty condition, as if all their internal parts had been partially digested. Mrs. Treat informs me that the plants which she cultivated in New Jersey chiefly caught Diptera.

65

Proc. Royal Soc.' vol. xxi. p. 495; and lecture at the Royal Institution, June 5, 1874, given in 'Nature,' 1874, pp. 105 and 127.

66

Since his original publication, Stein has found out that the irritability of the leaves was observed by De Sassus, as recorded in 'Bull. Bot. Soc. de France,' in 1861. Delpino states in a paper published in 1871 ('Nuovo Giornale Bot. Ital.' vol. iii. p. 174) that "una quantit di chioccioline e di altri animalcoli acquatici" are caught and suffocated by the leaves. I presume that chioccioline are fresh-water molluscs. It would be interesting to know whether their shells are at all corroded by the acid of the digestive secretion.

I am greatly indebted to this distinguished naturalist for having sent me a copy of his memoir on Aldrovanda, before its publication in his 'Beitrge zur Biologie der Pflanzen,' drittes Heft, 1875, page 71.

67

There has been much discussion by botanists on the homological nature of these projections. Dr. Nitschke ('Bot. Zeitung,' 1861, p. 146) believes that they correspond with the fimbriated scale-like bodies found at the bases of the petioles of Drosera.