THE EXTRACTION OF SAP FROM PLANT TISSUES 



BY PRESSURE 



ROSS AIKEN GORTNER, JOHN V. LAWRENCE and J. ARTHUR 



HARRIS 



{Station for Experimental Evolution, Cold Spring Harbor, N. Y.) 



(WITH PLATE l) 



(Received for publication, June 8, 1915). 



In a paper of great importance to those engaged in the study 

 of the properties of vegetable saps, Dixon and Atkins^ have shown 

 that a sample of sap obtained by pressing untreated tissues cannot 

 be regarded as typical of that contained in the tissue-mass, but that 

 fractions extracted successively differ essentially in their electrical 

 conductivity and depression of the f reezing point. Dixon and Atkins 

 have, furthermore, provided a method of obtaining typical samples 

 of sap by rendering tissues permeable by freezing in liquid air, and 

 have extended the application of this method to the extraction of 

 zymase from yeast.^ 



In the course of our work on the properties of vegetable saps we 

 have had occasion to repeat these studies of Dixon and Atkins on an 

 extensive scale. 



Dixon and Atkins contented themselves with methods vvhich 

 were qualitative rather than quantitative so far as the squeezings 

 are concerned. Such methods were, of course, quite sufficient for 

 their purposes. 



Our primary purpose has been to determine something con- 

 cerning the nature, amount, and regulär ity, of the change in the 



1 Dixon and Atkins : Osmotic pressures in plants. i. Methods of extracting 

 sap from plant organs. Sei. Proc. Roy. Dublin Soc. (n. s.), 13: 422-433, 1913. 

 Also, Notes from Bot. Seh. Trinity Coli. Dublin, 2: 154-172, 1913. 



2 Dixon and Atkins : The extraction of zymase by means of liquid air. Sei. 

 Proe. Roy. Dublin Soe. (n. s.), 14: 1-8, I9I4- Also, Notes from Bot. Seh. Trin- 

 ity Coli. Dublin, 2: 177-184, 1914. 



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