I9I51 



II A R VEY—ETII I 'LENE 



207 



to differ. On the foregoing assumption one may therefore say the 

 nature of the fats in the treated and untreated tissues is the same 

 as regards degree of saturation. 



For acidity determinations the epicotyls were collected as 

 described for the chemical analysis. The wet weight of the sample 

 was determined, but instead of being preserved in alcohol, the 

 tissue was directly triturated with water in a mortar. More water 

 was added to bring the mixture up to a definite volume, and finally 

 the free acids present were titrated with N/10 NaOH, using 

 phenolphthalein as indicator. The entire procedure, from the 

 cutting of the seedlings to the end of the titration, required about 

 one hour. The foregoing method is rather unsatisfactory; in 

 addition to the fact that in this way one estimates only the surplus 

 H-ions, other objections may be offered. However, any marked 

 relative difference can be caught by this method. 



The results obtained are found in table VII, expressed in terms 

 of N/10 NaOH required to neutralize 1 gm. wet weight of the tissue. 

 No consistent difference is evident between the treated and control 

 tissues. 



C. OSMOTIC PRESSURE AND PERMEABILITY 



Osmotic pressure was estimated by two methods, freezing point 

 and plasmolysis. For the former method, the juice was expressed 



