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494 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



and continued growth better after being placed in a full 



nutrient solution. 



(b). The period between 5 and 10 days in distilled water 

 is a crucial one for plants; if they remain longer in this 

 medium they are unable to recover normally or completely 

 when subsequently placed in a full nutrient solution. 



(c). By keeping the plants in distilled water a certain 

 period before transferring to full nutrient solution the ma- 

 turity of the plants is delayed. 



. The longest period during which plants can be kept 

 in distilled water and later recover on being placed in full 

 nutrient solution was found to be 30-40 days. For certain 

 dilute toxic solutions this period was much less, thus indicat- 

 ing that the so-called toxicity of distilled water is, if it exists 



at all, very slight. 



(e). The lateral roots of " boundary cultures' ' were 



characteristically long and thread-like. 



(f ). Sterilizing the distilled water by boiling one-half hour 

 every 4 days exercised a beneficial effect upon the growth of 

 plants in that medium as compared with the growth of those 

 in unsterilized distilled water. 



g). Greater total exosmosis was obtained in the renewed 

 than in the unrenewed distilled water. 



(h). Normal plants which have been grown for some time 

 in full nutrient medium and then transferred to distilled water 

 exhibit at first greater excretion than absorption of elec- 

 trolytes. After one or two days, however, there is greater 

 absorption than excretion and the conductivity curve declines. 

 This condition may be maintained for a considerable period. 



( i ) . The conductivity curve of the full nutrient solution in 

 which plants were grown rapidly fell during the first 15 days 

 or so; then it was more or less horizontal for a period, and 

 finally began to incline after about 50 days. The growth 



general opposite in character to the conducts 



curve. 



(j). The conductivity of the distilled water in one series in 

 which the roots of pea seedlings were placed was practically 

 the same on the 10th as on the 5th day. After the 10th day 



