Page:Makers of British botany.djvu/102

 72 some slight interest, for Newton died on March 20, and Vegetable Staticks must have been one of the last books he signed.

The dedication is to George Prince of Wales, afterwards George III. The author cannot quite avoid the style of his day, for instance: "And as Solomon the greatest and wisest of men, deigned to inquire into the nature of Plants, from the Cedar of Lebanon, to the Hyssop that springeth out of the wall. So it will not, I presume, be an unacceptable entertainment to your Royal Highness," etc.

But the real interest of the dedication is its clear statement of his views on the nutrition of plants. He asserts that plants obtain nourishment, not only from the earth, "but also more sublimed and exalted food from the air, that wonderful fluid, which is of such importance to the life of Vegetables and Animals," etc. We shall see that his later statement is not so definite, and it is well to rescue this downright assertion from oblivion.

His book begins with the research for which he is best known, namely that on transpiration. He took a sunflower growing in a flower-pot, covering the surface of the earth with a plate of thin milled lead, and cemented it so that no vapour could pass, leaving a corked hole to allow of the plant being watered. He did not take steps to prevent loss through the pot, but at the end of the experiment cut off the plant, cemented the stump and found that the "unglazed porous pot" perspired 2 ozs. in 12 hours, and for this he made due allowance.

The plant so prepared he proceeded to weigh at stated intervals. He obtained the area of the leaves by dividing them into parcels according to their several sizes and measuring one leaf of each parcel. The loss of water in 12 hours converted to the metric system is 1.3 c.c. per 100 sq. cm. of leaf-surface; and this is of the same order of magnitude as Sachs' result, namely 2.2 c.c. per 100 sq. cm.