[Vol. 2 



470 



ANNALS OK THE MISSOURI IIOTANICAL GARDEN 



renewed distilled water, and the same conditions for the dry 

 weight of tops and roots, gave the results to be seen in table n. 

 The total weight in all cases is therefore greater in the cul- 

 tures in which the distilled water was renewed. 



TABLE II (Series 1) 



EFFECT OF RENEWED VS. UNRENEWED DISTILLED WATER ON GROWTH OF 



HORSE BEANS 

 (Summarized Results of Part of Table I) 



Medium 



Green wt. of 

 tops in 

 grams 



Dry wt. of 

 tops in 

 grams 



Dry wt. of 



roots in 

 grams 



Water renewed . . . 

 Water unrenewed 



110.30 

 99.56 



13.219 

 12.287 



3.315 

 2.772 



These 



therefore indicate that the so-called injury 



to plants in distilled water cannot be entirely or even satis- 

 factorily explained on the basis of extraction of solutes from 



s. If that were the case we should have the 



and least recovery in those cultures in which 



periodically renewed 



the t)lant 



the distilled water was renewed, the per 

 water effecting in toto a greater exosmosis of the salts than 

 the water which is not renewed. This statement will receive 

 verification under the section on conductivity measurements. 

 It would therefore seem that we must seek other explanations 

 for the phenomena observed when plants are placed in dis- 

 tilled water. This phase of the subject will also be discussed 

 later. 



The points noted will be clear from an examination of pi. 13 



figs. 1 and 2. Plate 13 fig. 1 shows the various stages of 

 recovery after varying periods in the distilled water. The 

 better growth is to be noted of both tops and roots of No. 2, 

 in which the distilled water was renewed, as contrasted with 

 No. 1, in which it was not renewed. It is interesting to ob- 

 serve how plants, even after 20 days in distilled water, will 

 recover in full nutrient solution and then give even better 

 growth than plants in unrenewed full nutrient solution the 

 entire period, and that after 10 days in distilled water, plants 

 will recover in renewed full nutrient solution and equal in 



