Transpiration and the Ascent of Sap. 13 



tracheae. W e s t e r m a i e r 's hypothesis also, as has been often pointed 

 out, is quite inapplicable to Conifers, for in their wood there is no 

 vertical connection of cells placing- the medullary rays of various 

 levels in communication with one another. 



One of the most remarkable features in the discussion of the 

 Problem of the Ascent of Sap is that long before these Vital Hypo- 

 theses were conceived they had received decisive experimental refutation. 

 Boucherie^) in 1840, while experimenting on methods of injecting 

 timber for various technical ends, found that if a tree were cut across 

 at the base and supplied with a poisonous fluid, it not only drew 

 this fluid up to its highest leaves, but afterwards would draw up a 

 second solution when the latter was supplied. 



It is strange how the bearing of Boucherie's experiments 

 appears to have completely escaped the notice of Botanists, and it 

 may be noted that B i o t -), when commenting on Boucherie's work, 

 seems to find no special interest in it in connexion with the problem 

 of the elevation of the water of the transpiration current, but occupies 

 himself with other questions. B o u c h e r i e 's experiments did not wait 

 long for confirmation. A few years afterwards J. Schultz^) injected 

 trees in the same manner, but his results were also overlooked by 

 Botanists. 



It appears however to have remained for Strasburger to 

 point out the full significance of these experiments and to confirm 

 them with many more of his own, carried out with all possible 

 precautions. 



Godlewski, it will be remembered, held the view that the 

 function of the radial intercellular passages is to supply air to the 

 radial medullary ray cells, and to thus enable them b}'' respiration 

 to utilize their energetic substances in raising the sap. Stras - 

 burger^) tested this hj^^pothesis by coating a branch of Wistaria 

 sinensis 14 meters long for a length of 12"5 m with grafting wax. By 

 this means gaseous exchanges between the medullary ray cells and 

 the outer air must have been practically completely suspended. Yet 

 during 6 days of observation no marked change in the leaves above 

 appeared. At the end of this time the branch was cut across at its 



') Rapport sur une mémoire de M. le docteur Boucherie relatif à la conser- 

 vation des Bois. Compt. Rend., 11, 1840, pp. 894 et seq. 



^) J. B. B i 1 , Remarques scientifiques à l'occasion de la lettre de M. B o u c h e r i e 

 insérée au dernier numéro du Compte rendu. Compt. Rend., 12, 1841, pp. 357 et seq. 



*) J. A. Schultz, Neues, wohlfeiles und bewährtes Verfahren, das Holz zu 

 conserviren, dasselbe auch gegen Fäulniss, Schwamm und Wurmstich zu schützen 

 etc. Weimar 1844. Quoted byE. Strasburg er in Ueber den Bau und Verrichtungen 

 der Leitungsbahnen in den Pflanzen. Jena 1891, p. 624. 



*) E. Strasburger, Ueber den Bau und Verrichtungen der Leitungsbahnen 

 in den Pflanzen. Jena 1891, p. 609. 



