[Vol. 2 



522 ANNALS OF THE MISSOURI BOTANICAL GARDEN 





ilar and comparable to the untreated controls. Marked injury 

 resulted in the case of the heat, illuminating gas, MgCh, and 

 H2SO4, all in characteristic manner. The injury from KOH 

 was rather slow in manifesting itself, but the coloration of the 

 roots was a noticeable feature. An interesting condition to be 

 noted here, which holds true also in the later experiments, is 

 in regard to the effect of the heat and the illuminating gas. 

 It should be borne in mind that during these treatments the 

 roots remained in water. The tops only were affected and 

 died ; the roots remained white, turgid, and normal in appear- 

 ance even though the exosmosis from them had been exces- 

 sive, thus indicating a transfer of some electrolytes from the 

 tops and down into the medium through the roots. Later ex- 

 periments also substantiated the fact that abundant exosmosis 

 sometimes occurs from roots which remain normal in appear- 

 ance. The other agents (MgCh, H 2 S0 4 , and KOH) caused 

 more or less injury to both tops and roots. The exosmosis of 

 nutrients into the water from the affected plants is evident by 

 the greater growth of fresh pea seedlings placed in such water 

 as compared with the controls. Both peas and horse beans 

 grew somewhat better in fresh distilled water than in distilled 

 water in which pea seedlings had already been grown for 21 

 days. 



Further preliminary experiments along this line gave sim- 

 ilar results. Thus in another series, vigorous, thrifty plants 

 of Canada field peas grown 10 days in full nutrient solution 

 were transferred, after rinsing the roots, to distilled water, 

 some being untreated and others treated. The treatment con- 

 sisted in placing some of the cultures in an atmosphere of 



illuminating gas for 3 and 6 hours, and others in a gas-heated 

 oven for 1 and 2 hours where it was not aimed to keep the 

 temperature constant. For those cultures in the oven 1 hour 

 the temperature at the outset was 53 °C. and at the end 33 °C, 

 while for those remaining in the oven 2 hours the initial tem- 

 perature was 60° C. and the final 33° C. The conductivity of 

 the water was measured soon after the plants were placed in 

 it but before the treatment, and again 5 days after treatment, 





