Insectivorous Plants

20

Sachs remarks ('Trait de Bot.' 1874, p. 774), that cells which are killed by freezing, by too great heat, or by chemical agents, allow all their colouring matter to escape into the surrounding water.

21

As a control experiment bits of albumen were placed in the same glycerine with hydrochloric acid of the same strength; and the albumen, as might have been expected, was not in the least affected after two days.

22

'Leons phys. de la Digestion,' 1867, tom. ii. pp. 114-126.

23

'Leons phys. de la Digestion,' tom. ii. p. 145.

24

Dr. Lauder Brunton, 'Handbook for the Phys. Laboratory,' 1873, pp. 477, 487; Schiff, 'Leons phys. de la Digestion,' 1867, p. 249.

25

Dr. Lauder Brunton gives in the 'Medical Record,' January 1873, p. 36, an account of Voit's view of the indirect part which gelatine plays in nutrition.

26

'Leons,' &c. tom. ii. page 151.

27

Dr. Lauder Brunton, 'Handbook for Phys. Lab.' p. 529.

28

'Leons' &c. tom. ii. page 153.

29

Mr. A.W. Bennett found the undigested coats of the grains in the intestinal canal of pollen-eating Diptera; see 'Journal of Hort. Soc. of London,' vol. iv. 1874, p. 158.

Watts' 'Dict. of Chemistry,' vol. ii. 1872, p. 873.

30

Watts' 'Dictionary of Chemistry,' vol. ii. page 874.

I may add that Dr. Sanderson prepared some fresh globulin by Schmidt's method, and of this 0.865 was dissolved within the same time, namely, one hour; so that it was far more soluble than that which I used, though less soluble than fibrin, of which, as we have seen, 1.31 was dissolved. I wish that I had tried on Drosera globulin prepared by this method.

31

See, for instance, Schiff, 'Phys. de la Digestion,' 1867, tom. ii., p. 38.

32

'Leons phys. de la Digestion,' 1867, tom. ii., p. 304.

33

'Phys. de la Digestion,' 1867, tom. ii. pp. 188, 245.

34

See the classification adopted by Dr. Michael Foster in Watts' 'Dictionary of Chemistry,' Supplement 1872, page 969.

35

It is scarcely possible to realise what a million means. The best illustration which I have met with is that given by Mr. Croll, who says, "Take a narrow strip of paper 83 ft. 4 in. in length, and stretch it along the wall of a large hall; then mark off at one end the tenth of an inch. This tenth will represent a hundred, and the entire strip a million.

36

When my first observations were made on the nitrate of ammonia, fourteen years ago, the powers of the spectroscope had not been discovered; and I felt all the greater interest in the then unrivalled powers of Drosera. Now the spectroscope has altogether beaten Drosera; for according to Bunsen and Kirchhoff probably less than one 1/200000000 of a grain of sodium can be thus detected (see Balfour Stewart, 'Treatise on Heat,' 2nd edit. 1871, p. 228). With respect to ordinary chemical tests, I gather from Dr. Alfred Taylor's work on 'Poisons' that about 1/4000 of a grain of arsenic, 1/4400 of a grain of prussic acid, 1/1400 of iodine, and 1/2000 of tartarised antimony, can be detected; but the power of detection depends much on the solutions under trial not being extremely weak.

37

Miller's 'Elements of Chemistry,' part ii. p. 107, 3rd edit. 1864.

38

My son, George Darwin, has calculated for me the diameter of a sphere of phosphate of ammonia (specific gravity 1.678), weighing the one-twenty-millionth of a grain, and finds it to be 1/1644 of an inch. Now, Dr. Klein informs me that the smallest Micrococci, which are distinctly discernible under a power of 800 diameters, are estimated to be from .0002 to .0005 of a millimetre – that is, from 1/50800 to 1/127000 of an inch – in diameter. Therefore, an object between 1/31 and 1/77 of the size of a sphere of the phosphate of ammonia of the above weight can be seen under a high power; and no one supposes that odorous particles, such as those emitted from the deer in the above illustration, could be seen under any power of the microscope.)

39

Miller's 'Elements of Chemistry,' 3rd edit. pp. 337, 448. inflection. After describing the experiments, a few concluding remarks will be added.

40

See articles on Glycerine and Oleic Acid in Watts' 'Dict. of Chemistry.'

41

According to M. Fournier ('De la Fcondation dans les Phanrogames.' 1863, p. 61) drops of acetic, hydrocyanic, and sulphuric acid cause the stamens of Berberis instantly to close; though drops of water have no such power, which latter statement I can confirm;

42

Miller's 'Elements of Chemistry,' part i. 1867, p. 87.

43

'Quarterly Journal of Microscopical Science,' April 1874, p. 185.