456 Theory of the Nutrition [BOOK in. 



weighing five pounds was set in this pot, which was protected 

 by a cover from dust, and daily watered with rain-water. In 

 five years' time the willow had grown to be large and strong, 

 and had increased in weight by a hundred and sixty-four pounds, 

 though the earth in the pot, when once more dried, only showed 

 a loss of two ounces. Van Helmont concluded from this 

 experiment that the considerable increase of weight in the plant 

 had been gained entirely at the cost of the water, and conse- 

 quently that all the materials in the plant, though distinct from 

 water, nevertheless come from it. 



These objections to Aristotelian teaching on the part of 

 Jung and Van Helmont remained isolated and unproductive. 

 But an incentive to new investigations in vegetable physiology 

 was supplied from a different quarter, and its influence lasted 

 till far into the i8th century. This was the suggestion, that 

 not only does a nutrient sap taken up by the roots ascend to 

 the leaves and fruits of plants, but that there is also a move- 

 ment of the same sap in the opposite direction in the rind. 

 But this idea assumed from the first two different forms. Some 

 botanists, evidently resting on the analogy of the circulation of 

 the blood in animals, supposed that there was also an actual 

 circulation of the sap in plants ; others on the contrary were 

 content with supposing that while the watery sap absorbed by 

 the roots rises in the wood, an elaborated sap capable of 

 ministering to growth moves in the rind, the laticiferous vessels, 

 and the resin-ducts. The two views were at a later time 

 repeatedly confounded together, and those who refuted the 

 first believed that they had refuted the other also. It appears 

 that a physician from Breslau, Johann Daniel Major 1 , Pro- 



1 J. D. Major, who was born at Breslau in 1639, an ^ died a ^ Stockholm 

 in 1693, is quoted by Christian Wolff, as well as by Reichel (' De vasis 

 plantarum,' 1758, p. 4) and others, as the founder of the theory of circula- 

 tion, which he propounded in 1665 in his ' Dissertatio Botanica de planta 

 monstrosa Gottorpiensi,' etc. Kurt Sprengel (' Geschichte der Botanik, ii. 

 p 7) classes him also among the defenders of the doctrine of palingenesia, a 



