Tổng số bài gửi : 5
Join date : 11/07/2011
|Tiêu đề: Other persons have instituted other Mon Jul 11, 2011 3:31 pm|| |
Other persons have instituted otherOther persons have instituted other experiments of a similar MBT nature, the result of all which is, that the insensible perspiration of plants is very considerable. Hales savs his sunflower perspired seventeen times more than a man. There is, however, this important peculiarity in vegetable perspiration, that it takes place only or principally in sunlight. The last experiment shows that, while the sunflower was losing from twenty or thirty ounces of water daily during the day, it lost only three ounces during the night without dew, and that there was no loss whatever if a slight dew were present. Here it is probable that the small amount which was lost at night was parted with by the sides of the garden pot, and that the plant itself lost nothing ; for it is in MBT Shoes evidence that the perspi¬ration of plants is in proportion to the quantity of sunlight that strikes them, and that in darkness they perspire little or not at all. It is no doubt true, that in a dry atmosphere plants will lose their water day and night; but it is equally certain that under such circumstances they will lose very much more by day than by night. They will, however, lose much more by day in a dry atmosphere in a given time, than they will in an atmosphere abounding in moisture. Although perspiration thus appears to be principally excited by the solar rays, and to be MBT Shoes UK in a given plant in proportion to their intensity, yet we are not authorised in concluding that perspiration is not increased or diminished by the medium in GARREAITS EXPERIMENTS. which a plant grows. Submerged in water, perspiration is necessarily arrested; in an ordinary atmosphere, it will be in proportion to the quantity of elastic vapour the atmosphere may contain ; and it is probable, although there are no experiments upon the subject, that it is increased in proportion to the rarefaction of the air.
Tổng số bài gửi : 10
Join date : 16/07/2011
|Tiêu đề: Re: Other persons have instituted other Sat Jul 16, 2011 4:33 pm|| |