154 TRANSPIRATION AND ASCENT OF SAP ch. vii 



not lose their lustrous appearance or roll at the edges 

 till pressures between 26 and 38 atmospheres were 

 applied. Hence, under normal conditions we may believe 

 that the leaves of these plants will not show signs of 

 fading till tensions equivalent to 20-30 atmospheres are 

 generated. 



By means of this method useful results were obtained, 

 but danger attended the determinations. Despite the 

 strength of the glass cylinders used, two explosions occurred, 

 fortunately attended by delay in the work only, so that 

 after a comparatively small number of observations, a 

 more suitable method was looked for. 



Literature. 



Dixon, H. H., "On the Osmotic Pressures in the Cells of Leaves," Proc. 

 Roy. Irish Acad. vol. iv (Ser. 3), p. 61, and Notes from the Botanical School 

 Trinity College, Dublin, vol. i, p. 44. 



Id. "On the Physics of the Transpiration Current," Notes from the 

 Botanical School, Trinity College, Dublin, vol. i, p. 57. 



Id. " A Transpiration Model," Proc. Bog Dublin Soc. 1903, vol. x (N. S.), 

 p. 114, and Notes from the Botanical School, Trinity College, Dublin, vol. i, 



p. 217. 



Dixon, H. H.,and Joly, J., "On the Ascent of Sap," Phil. Trans. Roy. 

 Soc. London, 1895, vol. 186 B, p. 563. 



