1917] 



HA A S—PROTOPLA SM 



233 



method 



tance. 



M 



6 



crushed 



which is first expressed contains a much lower concentration of 

 electrolytes than that which is obtained when greater pressure is 



crush more 



It is obvious that when 



pressure is first applied and sap is squeezed out through the intact 

 plasma membrane, the electrolytes may largely be retained within 

 the cell because they are not able to pass freely through the 

 membrane. It is desirable, therefore, to grind the tissue and 

 rupture all of the cells. This was accomplished by thoroughly 

 grinding the tissue in a mortar. Only a little tissue was ground 

 at a time, and the grinding was continued until microscopic 

 examination showed that all the cells were ruptured. 



TABLE I 



I 



Material 



Actual acidity 



of CO*-free undiluted 



juice as determined 



by tbe gas chain 



Total acidity as 



determined by ordinary 



titration methods 



Lemon (fruit) 



Cranberries (fruit), fresh material, peeled 

 and unpeeled 



Grapefruit (fruit) 

 Apple (fruit) 



basal part 



Rhubarb (leaf-stalk)^ hltermedi f t K e {*"*•■ " 



v '* green part below\ 



leaf blade /" ' 



Orange (fruit) 



Pineapple (ripe fruit), juice standing 2 

 hours 



Pineapple (ripe fruit), fresh juice 



Green pepper (fruit) 



Eggplant (fruit) 



0.006N 



0.004N 



0.001N 

 0.0004N 

 0.0007N 

 0.0005N 



0.00022N 



0.00016N 



0.00009X 

 0.000035X 

 o 000003 8X 

 0.000002N 



0.9172X (ripe fruit) 

 o . 3 i94N\ (overripe, 

 o.3493N/soft fruit) 



o. 1927X 



O.071 iX 



0.1578* 

 0.1681X 



0.0941X 



0.1377X 



determining 



means 



>nt of hydrogen. The results of the deter- 

 minations are given in table I. The results in all cases represent 

 the average of two or more closely concordant determinations. 



Mameu 



6 



Marie, C. H., and Gatix, C. L., Determinations cryoscopiques effectives sur 



des sues veggtaux. 1912. 



Dixon 



