1915] 



MERRILL DISTILLED WATER 483 



spite of it the renewal of the water shows no baneful effects, 

 or indeed produces beneficial results, then may we well con- 

 clude, and with increasing assurance, that extraction of 

 nutrient salts is in no way responsible for any injury plants 

 undergo in distilled water. The results obtained strongly 

 substantiate that conclusion. 



A series of cultures (series 6) was set up in which healthy 

 plants of Canada field peas were grown in full nutrient solu- 

 tion for about three weeks and then transferred, after care- 

 fully rinsing the roots, to doubly distilled water. In half of 

 the cultures the distilled water was renewed at certain definite 

 intervals for each culture, while in the other half of the cul- 

 tures the water was not renewed. Conductivity determina- 

 tions were then made of the water under both conditions- 

 renewal and non-renewal— at certain regular intervals, vary- 

 ing for each set of cultures, for several days after the plants 

 had been placed in this medium. 



By numerous readings it was ascertained that with a resis- 

 tance of 9,110 ohms in the resistance box the average value of 

 x on the Wheatstone bridge for the water in the vessel after 

 being rinsed and before placing the roots therein was approxi- 

 mately 6.0, rarely varying 1 cm. either way. Considering that 

 figure, then, as the basis or the starting point for the exos- 

 mosis, and subtracting it from the different values found for 

 the renewed, and from only the final value obtained for the 

 unrenewed distilled water, we get the figures in the last column 

 of table viii. 



The plan of the experiment with respect to renewal of the 

 distilled water and the time of readings, the values of the 

 individual readings, and the comparative amounts which 

 represent the total exosmosis of the electrolytes under the 

 various conditions of the experiment are all given in table 

 viii. The numbers given are the values of x on the Wheat- 



ohms 



bridge when the resistance inserted in the box was 9 



It is thus seen that by far the greater exosmosis was ob- 

 tained in the case of those cultures in which the distilled water 

 was renewed. Another point of interest was the reabsorp- 



