520 



[Vol. 2 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



ings were made in the distilled water, the resistance in the re- 

 sistance box was 9,110 ohms. In some media other resistances 

 were used; in such cases the values are given only in tables, 

 and in terms of specific conductivity. 



TABLE I 



EFFECTS OF VARIOUSLY TREATED PLANTS ON THE DISTILLED WATER MEDIUM 



AS SHOWN BY GROWTH OF SECOND CROP 



Culture 



no. 



1 and 2 

 3 

 4 



5 



6 



7 and 8 



9 



10 



11 and 12 



13 and 

 15 and 



14 

 16 

 17 and 18 



19 and 20 



21 and 22 

 23 and 24| 



Controls — no treatment; full nutrient to dist. H 2 . . . 

 Plant tops packed in ice 19 hrs.; dist. H 2 unchanged 

 Plant tops packed in ice 19 hrs.; dist. H 2 changed. . 



In gas incubator at 50°C, 3 . 5 hrs 



In gas incubator at 50°C, 3.5 hrs 



Inoculated with Ascochyta Pisi 



Ilium, gas under bell jar, 6 hrs.; dist. H 2 unchanged.. . 



Ilium, gas under bell jar, 6 hrs.; dist. H2O changed 



N/1 MgClj in full nutrient as the solvent, 7 hrs 



.5% HjSCh in full nutrient as the solvent, 7 hrs 



1% KOH in full nutrient as the solvent, 7 hrs 



Plants grown throughout in dist. H 2 0; replaced by 



fresh seedlings in the unrenewed dist. H 2 



Same as Nos. 17 and 18, except that second crop was 



horse beans , 



Canada field peas in fresh dist. H2O; no second crop . . . 

 Horse beans in fresh dist. HjO; no second crop I 





Green wt. of 



tops of 2nd crop* 



grams 



2.90 



2.80 



1.60 

 2.55 

 2.80 

 2.75 

 2.25 

 5.20 

 2.30 

 8.45 



2.55 



6.85 

 2.82 

 8.15 



*The 2nd crop was 27 days old at time of weighing. 



Canada field 



IV. Preliminary Experiments 



In order to determine in a preliminary way whether the 

 exosmosis from the roots of plants seriously affected by in- 

 jurious agencies was sufficient to noticeably influence a new 

 crop of seedlings in that medium (distilled water plus the ex- 

 creted substances) as compared with control cultures in pure 

 distilled water, the following series was set up. 

 pea seedlings were grown in full nutrient solution until they 

 were 15 days old, at which time they were about 8 inches high, 

 and were green, vigorous, healthy, and in good condition. They 

 were then treated in accordance with the plan given in table i. 

 In some cases, depending on the nature of the agent applied, 

 the treatment was given after the plants had been transferred 

 to distilled water. This was the case with Nos. 3, 4, 5, 6, 9 and 

 10. Cultures 7, 8, and 11-16 were treated while still in the 



