Essays and observations on natural history, anatomy, physiology, psychology, and geology / by John Hunter, being his posthumous papers on those subjects, arranged and revised, with notes ; to which are added the introductory lectures on the Hunterian collection of fossil remains delivered in the theatre of the Royal College of Surgeons of England, March 8th, 10th and 12th, 1855 / by Richard Owen.
- John Hunter
- Date:
- 1861
Licence: Public Domain Mark
Credit: Essays and observations on natural history, anatomy, physiology, psychology, and geology / by John Hunter, being his posthumous papers on those subjects, arranged and revised, with notes ; to which are added the introductory lectures on the Hunterian collection of fossil remains delivered in the theatre of the Royal College of Surgeons of England, March 8th, 10th and 12th, 1855 / by Richard Owen. Source: Wellcome Collection.
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![similar to those whose stalks only live the same summer, but the roots live, and shoot out new stalks; however, it is never the last or former year's shoots that throw out leaves, it is a new shoot. The second is what may he called , or the second season of its age, or when it has finished the second growth. This would be similar to the Raspberry ; for the Raspberry does not die in the same season of growth, as many vegetables do, but in the second season, as do the leaves of .the Scotch and Weymouth Pines, Laurel, &c. The third may be called , or the third season of its age, or when it has finished its third shoot, as in the There may be a fourth, a fifth, a sixth difference in regard to the times of casting the leaves; the last of which seems to be the case with the Spruce. Every winter exemplifies the first class, and in all of the Pine-kind this fact is easily known; but in most others of the second, third, &c. [difference as to times] the facts can only be known by a succession of observations. The casting of the leaves of plants is most probably similar to sloughing or exfoliation in animals. It is at least an operation of the plant, producing a separation of the leaf; and the only thing that proves it is, that the leaf will not fall off if the plant, and of course the leaf, be dead; but if the leaf dies, although long before its destined time, it withers, is separated, and falls off; but if both the plant and leaves die at the same time, viz. before the separation has taken place, then the leaf will not fall off, even when dried. These facts show gardeners whether a new transplanted plant is dead or alive. If the leaves fall off by passing the hand over them, then they are sure the plant is alive; but if they do not fall off of themselves, nor can be separated by passing the hand over them, then it is most probable that the plant is dead. Of the Change of the Colour of Leaves and StalJcs of Vegetables from the Green to the Yellow when dying.—This change is an operation of the living powers of the plant, and not simply death taking place. It is extremely gradual when the part is as it were allowed to die a natural death ; but either a great drought or a few frosty evenings will hasten on the decline, and they die sooner or faster. That it is an operation of the plant arising from debility or the stimulus of death, is, I think, evident; for if a plant in full vigour, in which it is at the greenest, be killed immediately, by putting it into boiling water or by electricity, it retains its green coloiu-, and will die green, and even dry that colour : whence we may suppose that the strongest plants, or those with the greatest powers of action of any one species, will be of the deepest green ; and I believe that this is shown every day by experience.](https://iiif.wellcomecollection.org/image/b21182656_0390.jp2/full/800%2C/0/default.jpg)
