CHAPTER I. 



METHODS OF MEASURING ELECTRICAL 



CONDUCTIVITY 



SINCE the conclusions set forth in this work depend 

 largely upon researches on the electrical conductivity of 

 organisms it seems desirable to give an account of the 

 methods of conducting such investigations. 



In the experiments of some investigators 1 platinum 

 electrodes have been applied directly to the tissue. It 

 is difficult to obtain good contact by this method and 

 there is danger that some of the platinum black may be 

 rubbed off. Kodis (1901) states that it is impossible 

 to obtain trustworthy results in this manner. He there- 

 fore placed the tissue in a U-tube in each arm of which 

 was a funnel plugged at the bottom with plaster of Paris. 

 Each funnel was filled with a solution of NaCl into which 

 an electrode dipped (Fig. 1). 



In measuring the conductivity of red blood corpuscles 

 or of unicellular organisms the electrodes are placed 

 directly in a suspension of the cells, either with or with- 

 out previous centrifugation. 2 (Fig. 2.) 



In experiments of the writer on unicellular plants 

 (such as Euglena and Chlorella) the organisms were 



Regarding methods see Galeotti (1903), Alcock (1905, 1906), Polacci 

 (1907), Mamelli (1909), Stone and Chapman (1912), Henri et Calugareanu 

 (1902, A, B), McClendon (1912), Stiles and Jorgensen (1914), Hober 

 (1914) pp. 381, 440, Small (1918). 



'See R6th (1897), Bugarsky und Tangl (1897), Stewart (1897, 1899, 

 1909-10), Woelfel (1908), McClendon (1910), Gray (1913, 1916), 

 Shearer (1919, A, B, C). 



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