476 Theory of the Nutrition [BOOK in. 



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 *, 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 trans- 

 lations ; 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 investi- 

 gations. An abundance of new experiments and observations, 



1 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 ' His- 

 toire de 1' Academic Royale des Sciences,' 1762. 



