1902] 



ELECTRICAL CONDUCTIVITY OF PLANT JUICES 



87 



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I 



The specific conductivity for the aerial stems is higher than 

 that for either leaves or tubers, while the amount of crude ash 

 follows the general law already stated that the amount of ash 

 increases from the roots upwards to the leaves. Repeated 

 determinations of the conductivity of the juice taken from dif- 

 ferent specimens showed similar results, hence it is evident that 

 the conditions here are different from what was found for Beta 

 vulgaris. ■ Considering only the tubers and the leaves, the results 

 again show the conductivity to be a rough estimate of the rela- 

 tive amount of ash ; but for the aerial stems the conductivity is 

 higher than it should be if ash alone is concerned. How then 

 IS the greater conductivity of the juice from the aerial stems to 

 be explained ? It is quite probable that it is due in part at least 

 to the greater amount of organic acids present. Titrations of 

 the juice are extremely difficult on account of the color, even 

 when the juice is considerably diluted, but the titrations made 

 mdicated more acid than in either leaves or tubers, Vv^hich are 

 rather alkaline. This conclusion is also substantiated by the 

 specific conductivity of the ash solution, which is considerably 

 less than obtained for the original juice. The relative amount 

 of ash obtained bv 



by Wolff'' for leaves and tubers was slightly 

 different from the above table. His analyses show that the 

 leaves contain nearly three times as much crude ash as the 

 tubers, but a considerable difference was shown by plants taken 

 at different periods in their growth. The different proportions 

 obtained may then be due to the different times and conditions 

 of growth. 



3, Allium cepa. 



The juice obtained from both leaves and bulbs was measured 

 with the following results : - 



Leaves 



Eulb 



Sp. conf', of 

 juice 



Crude ash from 



cc 



0.0125 



0.00525 



0.047 



0.0229 



Sp. cond. of ash 

 sol. 



0.00921 



. 00446 



zx 



Wolff, Aschenanalysen, p. 75. 



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