CHAPTER VI. 

 CONDUCTIVITY AND PEEMEABILITY 



It is well known that death is accompanied by an 

 increase of permeability. Thus a slice of red beet kept 

 in water will live for a long time without giving off pig- 

 ment, but as soon as it is killed the color begins to escape 

 from the cells. In this case the coloring matter is dis- 

 solved in the large central vacuole which fills the interior 

 of the cell. In order to escape, it must pass out through 

 the layer of protoplasm which surrounds the vacuole. 

 As long as the protoplasm remains in its normal condi- 

 tion it is impermeable to the dissolved pigment, but as 

 soon as death occurs it become freely permeable and the 

 color escapes. 



We meet the same condition if we study the penetra- 

 tion of substances from without. It is a matter of 

 common observation that cells may resist the penetration 

 of certain dyes as long as they 'are alive, but absorb 

 them readily as soon as they are killed. 



The increase in permeability which accompanies 

 death is paralleled in a striking manner by a simultaneous 

 increase in electrical conductivity.^ This suggests that 



'An apparent exception to this statement is found in two articles by 

 Galeotti (1901, 1903) who states that death produces an increase in the 

 electrical resistance of muscle, kidney, etc., followed by a decrease. He 

 suggests that the increase is due to the fixation of electrolytes by the 

 tissues. In Galeottl's experiments the tissues were not Immersed in solu- 

 tions and in consequence the electrodes had to be applied directly to the 

 surfaces of the tissue. It is possible that his results were due in part to 

 faulty technique (bubbles of gas readily form in dying tissue, increasing 

 the resistance). The matter requires further investigation. 



Kodis ( 1901 ) whose technique seems to be decidedly preferable to 

 that of Galeotti, (see page 21) found that dead frog muscle had less 

 electrical resistance than living. The writer has confirmed this, using the 

 method employed by Kodis. 



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