On the rise of the sap in the spring / Edwin Sidney.

  • Sidney, Edwin, 1798?-1872.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: On the rise of the sap in the spring / Edwin Sidney. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Ino and Bacchus—Little Nell—Psyche, in Cheverton’s Machine Sculpture. [Exhibited by W. T. Copeland, Esq.] Partridge and Woodcock, worked in Leather, in imitation of Wood- Carving, by Mr. W. Sanders. Portraits of John Dalrymple, Esq., F.R.S. and of Dr. Holland, F R.S , by J. Z. Bell, Esq. Mr. C. Varley exhibited several interesting objects by the Micro- scope. WEEKLY EVENING MEETING, Friday, May 14. Sir Charles Fellows, Vice-President, in the Chair. The Rev. Edwin Sidney, / On the Rise of the Sap in the Springy After a few prefatory observations, the speaker divided the subject into four parts which he proposed to consider in order. 1. A short description of certain physical phenomena to be regarded as preparatory. 2. Their application to the known organism of vege- table structures. 3. The circumstances under which these organisms will be called into that activity which may be regarded as the proximate cause of the rise of the sap in the spring. 4. The diffusion of the sap through the plant. The inquiry was limited of course to plants of our own climate. 1. In directing attention to the first part of the subject, it was observed that vitality must not be disregarded. The most chemical and physical forces fail to explain all. Vital force is mysterious, it is true, but so are all forces. If there were not a living formative force su- peradded above dead physical forces, all the varieties of organized sub- stances could not originate as they do from a simple vesicle. The phe- nomena now to he considered were those of capillarity and endosmosis. The former is greatly affected by temperature, and the imbibition due to it dift'ers much in different liquids and solutions. Endosmosis is known as the phenomenon of the mixture of two liquids of unequal density through a membrane, aecompanied by a change of volume. It is called endosmosis when the volume increases, exosmosis when [t diminishes. It is generally, but not always, found that when the iieavier liquid is above the lighter, mixture is accelerated by the nterposition of the membrane. Other things equal, the force of he current varies as the excess of the density of the interior iquid proportional to water. A current with a pressure of several