470 Theory of the Nutrition [book in. 



of growth. It found a new supporter in 1680 in the person of 

 Claude Perrault, who does not however appear 1 to have added 

 anything essentially new to Malpighi's conclusive arguments 

 for a returning sap. Nor did his opponent Magnol in his very 

 weak treatise published in 1709 succeed in saying anything 

 that will bear examination against the theory of circulation, 

 which he too ascribed to Malpighi. 



Among the phenomena of vegetation in woody plants, there 

 is scarcely one so striking as the outflow of watery sap from 

 wounded vines and from some tree-stems in the spring. This 

 phenomenon, like the outflow of milky juice, gum, resin and 

 the like, could not fail to be regarded with lively interest by 

 those who occupied themselves with vegetable physiology in the 

 17th century. Even supposing the movements of water in the 

 wood and of the milky and other juices in their passages not 

 to be necessary accompaniments of the nutrition of plants, yet 

 it was natural that the physiologists of the 17th century should 

 see in them striking proofs of that movement of the sap which 

 is connected with nutrition, and should therefore make them 

 a subject of study. It might also seem to them that the 

 problem in question was easy to solve, for it was not till long 

 after that it came to be understood that these movements are 

 in reality one of the most difficult questions of vegetable 

 physiology. We discover the interest taken in these matters 

 from a series of communications in the form of letters from 

 Dr. Tonge, Francis Willoughby, and especially from Dr. 

 Martin Lister, to be found in the Philosophical Transactions 

 for 1670 2 . The phenomenon to which these men chiefly 

 directed their attention was just the one best calculated to 



1 His views are known to me only from Magnol's paper in the ' Histoire 

 de l'Academie Royale des Sciences,' 1709, and Sprengel's 'Geschichte der 

 Botanik,' ii. 20. Perrault's treatise is according to Pritzel's • Thesaurus' of 

 the date of i6So, but is published in the ' GEuvres divers de Perrault' of 

 1721. 



3 Especially in pages 1165, 1201, 2067, 2119. 



