Dixon and Atkins — Osmotic P^-essures in Plants. 



427 



pressure is needed to obtain the sap, which flows easily from the tissues 

 without requiring the disruption of the cells. At the same time the sap is 

 much freer from the debris of broken cells than that from an untreated leaf. 

 This sap, so far as our experiments have at present gone, has always given a 

 greater depression to freezing-point and usually a higher conductivity than 

 that from the same tissues untreated. Furthermore, these determinations 

 differed from similar measurements made on sap of the same tissues exposed 

 to toluene vapour. The results are tabulated here : — 



These results show conclusively that the concentration of the sap pressed 



