ABSORPTION AND MOVEMENT OF WATER 119 



empty spaces; second, upon the living cells of the aerial 

 parts, in the leaves, branches, and stems, in which the solu- 

 tions are worked over and from which the water is given off. 

 The living parenchyma cells near the absorbing cells in the 

 roots, and the living parenchyma cells composing the food- 

 making tissues in other parts may be many metres apart. 

 The absorbing and consuming tissues of herbaceous plants 

 are usually close together; in tall trees they are separated,* 

 but are farthest from each other in some of the "lianes." 

 How is the water raised from the low levels at which it enters 

 the vascular bundles, in the region where it is absorbed from 

 the soil, to the cells needing it but far removed?! This ques- 

 tion has occupied botanists from the time when physiolog- 

 ical experiments were first undertaken until now. Despite 

 the most acute study, the question — one of the most allur- 

 ing and important in botany — is still unanswered. Hy- 

 potheses, deserving respectful consideration both because of 

 their reasonableness, and also because of the fame of their 

 authors, have succeeded one another in the text-books, have 

 been accepted and then discarded, according to the prevail- 

 ing fashion. As Sachs was for many years the leading 

 plant-physiologist, so his idea, laid down in his writings 

 with all his brilliant power, that the water ascended only 

 through the walls of the wood-elements, J was the only one 

 echoed by the smaller text-books. Then followed § Godlew- 



* From Kerner and Oliver's Natural History of Plants these "certified 

 estimates" of heights and lengths are quoted: — 



Eucalyptus amygdalina — 140-152 metres — page 722, vol. I., part 2. 



Sequoia gigantea 79-142 " " " " " " " 



Calamus Eotang 200 " " 677, " " " " 



In his Silva of North America, Vol. X., p. 141, Sargent makes the 

 following statement regarding Sequoia sempervirens : "The Redwood, 

 which is the tallest American tree, probably occasionally attains the height 

 of four hundred feet or more. The tallest specimen I have measured was 

 three hundred and forty (340) feet high." 



f While this book is in the press, Copeland is publishing in the Botanical 

 Gazette, vol. 34, 1902, ' The rise of the transpiration : an historical 

 and critical discussion." 



X Sachs, J. von. The Physiology of Plants, Oxford, 1887, pp. 241-242. 



§ Godlewski, E. von. Zur Theorie der Wasserbewegung in den Pflanzen. 

 Jahrb. f. wiss. Bot., 1884. 



