1915] 



MERRILL ELECTROLYTIC DETERMINATION OF EXOSMOSIS 



557 



At the end of 13 days in distilled water following the treat- 

 ment, the tops of Nos. 11-20 were of the same appearance 

 throughout, i. e., normal. The roots were also nracticallv nor- 



mal in the case of Nos 



20, except for a brownish 



those of Nos. 12, 13, 15, and 16-18, being: especially evident 



the case of No 



In addition to being brown, however 



the roots of No. 11 were considerably flaccid. 



Figure 18 shows similar relations for NaCl, KC1, and CaCl 2 . 

 It is seen that KC1 is more effective than NaCl in causing exos- 

 mosis. Far from ameliorating the exosmotic condition, the 

 treatment with combined NaCl and KC1 likewise yields high 

 conductivity readings of the medium, the N/10 concentration 

 of each combined giving the highest. It can not be argued 

 that this effect is due solely to the osmotic pressures of the 

 solutions of the agents in question, for if that were the case 

 we should expect more comparable results on the basis of the 

 osmotic effects of the various solutions at the concentrations 

 used. There is a reduction in the effect when the NaCl and 

 KC1 used singly are reduced to concentrations of N/20. 



The condition of the plants 16 days after first applying the 

 treatment, or 13 days after being in distilled water, is shown 

 in table ix, from which it is evident that there was great exos- 

 mosis with but little or no visible effect accompanying it. 



TABLE IX 



CONDITION OF PLANTS TREATED WITH VARIOUS SALTS FOR 



DIFFERENT PERIODS OF TIME 



Culture no 



Condition of tops 



Condition of roots 



21 and 22 

 23 



24-28 



Normal 

 Dead — badly wilted at end of 



29 and 30 



treatment 



Normal 



Normal 



Slightly brown and 

 very slightly flaccid 



Very limp and flaccid 

 and brownish 



Very slightly brown- 

 ish but practically 

 normal 



Practically normal 



That osmotic effects play practically no part in the phe- 

 nomenon under consideration is indicated from the results of 

 Loeb ('03) on Gammarus and those of True ('14) on Lupinus 

 seedlings. The writer also performed experimental work to 



