air and the capillarity of the woody tubes as his moving forces.
He agrees decidedly with those who postulated a returning
sap as well as an ascending crude sap, but he appeals in this
matter to Major, Perrault, and Mariotte, and not to Malpighi;
yet like Malpighi he notices the growth of trees set upside
down as a proof that the juices can move in opposite directions
in the conducting organs, and with Mariotte he ascribes the
enlargement of growing organs to the expanding power of the
juices which force their way into them.
But these well-meant efforts on the part of Christian Wolff, and indeed all that was done from Malpighi and Mariotte to Ingen-Houss to advance the knowledge of the nutrition of plants, was thrown into the shade by the brilliant investigations of Stephen Hales[1], in whom we see once more the genius of discovery and the sound original reasoning powers of the great explorers of nature in Newton's age. His 'Statical Essays,' first published in 1727, reappeared in two new editions in English, and afterwards in French, Italian and German translations; in the last with a preface by Christian Wolff. This was the first work devoted to a more complete account of the nutrition of plants and of the movements of the sap in them, and while it noticed what had been already written on the subject, it was chiefly composed of the author's own investigations. An abundance of new experiments and observations,
- ↑ Stephen Hales was born in the county of Kent in 1677 and was educated at home without showing any special ability. At the age of nineteen he became a member of Christ's College in Cambridge, and there showed his taste for physics, mathematics, chemistry, and natural history. Nevertheless he took orders and held Church preferment in different counties. He became a Member of the Royal Society in 1718, and read before it his 'Statical Essays.' His 'Haemostatics ' appeared in 1733. He made and published other investigations and discoveries of very various kinds before his death in 1761. He was buried in his church at Riddington, which he had rebuilt at his own cost, and the Princess of Wales caused an inscription to his memory to be placed in Westminster Abbey. See his Eloge in 'Histoire de l'Academic Royale des Sciences,' 1762.
