[Vol. 2 



472 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



of Nos. 1 and 2, especially as regards length and the amount 

 of lateral root development. The root growth in No. 13 at 

 the end of the experiment was also greater than that in 

 No. 11 ; but in Nos. 12 and 14 it was about equal. The plants 

 of No. 17 also showed greater root growth than did those of 

 No. 15, and this difference was more marked than in the case 

 of the tops. The lateral roots in No. 17 were produced all 

 along the main roots, while in No. 15 they were practically 

 confined to the upper or older portion of the main roots. An- 

 other interesting difference observed was that in No. 17 the 

 main root tips were not permanently injured in the distilled 

 water and when placed in the full nutrient solution they con- 

 tinued growth. This was not the case in No. 15. In general 

 there was not much difference between the roots in Nos. 16 

 and 18; the plants in No. 18, however, had slightly greater 

 growth of roots and showed less injury and some continua- 

 tion of growth of the tips, whereas those in No. 16 did not. 

 The same condition of the roots above noted for Nos. 15 and 

 17 held also in Nos. 19 and 21 respectively ; but the difference 

 in favor of the renewal of the distilled water though less 

 marked was nevertheless evident. Likewise, Nos. 18 and 20 

 were similar to Nos. 16 and 18 respectively. 



Strong evidence was therefore afforded by the cultures of 

 horse beans that renewing the distilled water has a favorable 

 effect upon the plants. 



& 



Series 2 is in every respect a duplicate of series 1 except 

 that Canada field peas (Pisum sativum) were used instead 

 of horse beans (Vicia faba), and that the dry weight of the 

 tops was not determined; furthermore, the length of the ex- 

 perimental period was different. The condition of the media 

 and duration of growth, the green weight of tops, and the 

 dry weight of roots are given in table in, seven plants being 

 grown in each culture. An examination of this table reveals 

 results similar in many cases to those contained in table i; 

 plants recovered even after 20 days in distilled water, but 

 after 10 days in this medium the recovery was not so com- 

 plete as in the case of the horse beans, for the plants so treated 

 did not equal in growth similar ones which had remained in 



