SOME RELATIONS OF PLANTS TO DISTILLED 



WATER AND CERTAIN DILUTE 



TOXIC SOLUTIONS 



M. C. MERRILL 



Formerly Research Assistant to the Missouri Botanical Garden 



I. Introduction 



In view of the extensive use of distilled water as a medium 

 in which to grow control plants for comparative purposes in 

 solution-culture work, there is well-grounded justification for 

 the performance of considerable experimental work in order 

 to determine more definitely the relations of plants to this 

 medium. The subject is an important one, and it will require 

 much experimentation for the ultimate solution of all phases 

 of the problem involved. While the results herewith reported 

 are only preliminary in their nature, the fact that they give 

 positive indications along certain lines has been deemed 

 sufficient warrant for their publication at this time. In addi- 

 tion to determining the growth relations of plants in this and 

 other media, consideration has also been given to the effect 

 produced by growing plants in this medium as determined 

 by means of electrical conductivity measurements. 



II. Historical Aspects of the Subject 



The relation of plants to distilled water is a matter that 

 has been under more or less serious consideration at differ- 

 ent periods for a long time. Woodward (1699), who first em- 

 ployed the method of water culture in 1691-1692 in his interest- 

 ing experiments, found that plants grew better in river 

 water than in either rain water, spring water, or distilled 

 water. The difference was of course due to the quantity of 

 plant food contained in the medium, and this idea, coupled 

 also with the character of the nutrients, has been the basis 

 for a vast amount of physiological work since that time. 



Coming down to more modern times, there has been a 

 diversity of opinion among the investigators 



Ann. Mo. Bot. Gard., Vol. 2, 1915 



of the subject 



(459) 



