[Vol. 2 



476 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



nutrient solution for the entire period, or those which re- 

 mained in distilled water for a shorter period before being 

 transferred to the full nutrient solution. The growing season 

 of the former is thus prolonged and the date of maturity 



delayed. 



The foregoing series having given evidence of the recovery 

 of plants in full nutrient solution after being in distilled 

 water for 20 days, the question arose as to the maximum 

 length of time plants might remain in distilled water without 

 preventing recovery when subsequently transferred to full 

 nutrient solution. Series 3 was therefore set up. This con- 

 sisted of cultures of Canada field peas grown in distilled water 

 for 10, 20, 30, 40, and 50-day periods before transfer to the 

 full nutrient medium. The condition of the media and dura- 

 tion in each and also the results of the series (as shown by 

 the green weight of tops) are given in table v, Nos. 1-20 in- 

 clusive. Renewals in this series also were made every four 

 days. Nos. 21-28 under different conditions and concen- 

 tration of nutrient solution are given for purposes of com- 

 parison. The maximum time limit in distilled water above 

 referred to is thus seen to be approximately 30 days, and this 

 was practically attained only in case of the cultures in re- 

 newed distilled water. After 40 days in distilled water, 

 whether renewed or unrenewed, the recovery was almost nil, 

 though somewhat better in the renewed, while after 50 days 

 in either renewed or unrenewed distilled water all the cultures 

 were dead. 



In the 10 cases furnishing comparisons between cultures in 

 which the full nutrient solution was preceded on the one hand 

 by renewed and on the other by unrenewed distilled water, 

 greater growth was attained in 7 cases where the distilled 

 water was renewed. The total weight of green tops is more 

 nearly equal in the two sets of cultures, however, being 24.20 

 grams in the case of those in the unrenewed and 22.38 grams 

 in the case of those in the renewed distilled water. We thus 

 see that no injurious effects attend the renewal of the distilled 

 water when compared with the non-renewal of the same; on 

 the other hand, positive benefits are derived from such a 



