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enters into

leaves that bear the flowers.

The line of life say intense study: though till now I have not had the courage to lay the result before the public, till I found, that my discoveries were likely to be superseded and published from the study of others: as I discovered, six years ago, the second organ in plants, which was so well explained in a paper in your excellent Journal, though rather too obscure. I have not mentioned the sensitive plants, because I have not yet completed my study of them; but I must observe, they so intirely confirm my idea, that "the motion of plants is caused almost wholly by the spiral nerves," that when I lay them before the public, they will I hope eradicate every remaining doubt that may be left in the mind: and that they are only more or less sensitive, as the length to which they are fastened is more or less extended. DEAR SIR,

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Your obliged Servant,

Belleveu, June 12th.

A. IBBETSON.

Explanation of the Figures.

Plate VIII, Fig. 7. Divisions of the wood in the stem of trees; a, the rind; b, the bark: e, the inner bark; d, the wood; e, the spiral nerves; f, the line of life; g, the pith; h, h, the silver grain; o, o, o, the bastard grain. Fig. 8. Cylinders of the inner bark.

Fig. 9. Cylinders of the wood.

Plate IX. Fig. 10. Part of a branch showing the manner in which the line of life, cc, enters into the flower bud, a, and passes by the leaf buds bb; also the manner in which it runs to avoid an injured part.

Fig. 11. A flower bud, showing the line of life, cc, running up to each flower, a, a, a, a, a, a, a, and the pith terminating at b.

Fig. 12. A seed vessel of the class syngenesia; a, the calyx, b, female florets, c, male and female florets.

Fig. 13. Section just above the seed vessel of the dianthus. a, the calyx proceeding from the bark; b, the corolla, from the inner bark; c, c, c, c, c, ten stamens from the wood; d, the seed vessel; e, the pistil from the circle of life.

III. On

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III.

On the supposed Perspiration of Plants. By Mrs.

SIR,

AGNES IBBETSON.

To Mr. NICHOLSON,

A FRIEND has suggested to me, that, to avoid all mis- Moisture mis

taken for perspiration should

enormous.

takes, I should have described the various kinds of moisture, that might be taken for the perspiration of plants; lest the be described. subject, from their appearance, should be given up as a dream of the author's, without a fair and candid trial. It is certainly worth it, for great must be its influence on Perspiration as cribed to plants the atmosphere, and immense the calculation of the water necessary to afford such a perspiration, if we take into account also the quantity wanted for their growth. But, I may say, if leaves exude, in proportion to their surface, as much moisture as a healthy man, they must often drop water in the driest days; which I never could perceive they did. But if (as is insisted on) they yield 17 times as much as a robust subject, every tree must be a shower bath, and we could not sit under one without a complete wetting *.

moisture on

Of the various appearances of moisture, which the solar Different kinds microscope so completely elucidates, I shall first mention of apparent the honey dew, though there are few not acquainted with plants. its appearance. Beside this, there are three others, ons the bladder in which a small insect infolds its larva; another sort in which an insect lays her eggs; and the third is. the sickness of a plant; for there are few plants, that, do not give out a sort of sugar when ill. After these I must mention the egg of some insect. It is found on the proteas, and one or two other plants. I have preserved the eggs till the animals showed themselves. The next is the cryptogamia found on the pea, the sun flower leaf, the mimulusy and a few others; of these I have given a sketch, just as I took them from the solar microscope, that every one may judge whether this looks like the perspiration of a

This does not follow, unless some cause were present, to condense the aqueous vapour perspired. C..

plant.

No perspiration visible with a very high magifying power.

the cryptoga.

mian plants on leaves,

and causes unnatural secre

plant*. I have also seen the beginning of the hairs of the leaf taken for it.

In the three or four years that I have been (as long as the leaves last) endeavouring to discover perspiration, it appears to me impossible I should not have found it, if it did exist: but I have sought it with microscopes that magnified so extremely, as to prevent my being deceived by other objects. I regret indeed the little use made of an instrument now carried to a degree of perfection, which must daily bring new wonders to our admiring senses. With respect to perspiration, it is so little shown, though the smallest hairs of the leaf are enlarged to the size of a ruler, and the water is seen running up as the rarefaction of the air forces it from the increased warmth of the glass. Nay, the pores of the leaf are so enlarged, that an object five times as small could be seen and examined: why then should I not see moisture, if it existed?

In my former papers (which were written a long time. since,) I did not mention (because I was not fully aware of it) the very defective manner made use of to try the quantity of perspiration given by plants, and to evince its existence, till the desire of studying the effect of various degrees of heat on plants, made me a constant attendant on the hotHeat increases house, green house, hot walls, and glasses, &c. I then found, that any increase of heat helped greatly to increase the number of cryptogamian plants on those leaves, on which they were not at all inclined to grow; and that, beside this, they produced secretions unknown to the plant in its natural situation. The melon gives a very curious one, found on the edge of the leaf of the plant every morning: but, instead of covering the plant from all air, leave it a little by raising the glass, and the moisture intirely ceases. It is the The cucumber, same, though not so much, with the cucumber. There is not the smallest appearance of moisture without the plant is first rendered ill, to study its secretions. It is objected to me, that I left the plant so long (being three hours) that

tions.

The melon.

*See Plate IX, Figs. 15, and 16, the cryptogamian plant on the mimulus, or monkey flower: fig. 17, those on the pea, which are recumbent: fig. 18, those on the sunflower. They seldom appear on young leaves, or on any leaf, till the plant is near flowering.

the

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