﻿i 9 i6] RIGG, TRUMBULL, LINCOLN—TOXIC SOLUTIONS 415 



middle of September, when the levels for the year were the lowest. 

 He found that the osmotic pressure of the waters tested (expressed 

 in mm. of mercury) varied from 59 to 407. Those tested by the 

 writers (table II) varied from o to 70. The waters of the Puget 

 Sound region are soft, possessing very little of even temporary 

 hardness. 



In so far as the data given in this paper are concerned, the 

 seasonal variation of osmotic pressure in the waters of the sphagnum 

 bogs in the Puget Sound region seems to be the opposite of that of 

 the waters of springs and lakes. 



The surface tension of bog water was measured in order to deter- 

 mine whether it might be low enough to cause exosmose from the 

 root cells of plants growing in the bogs. Blackman (i) and 

 Czapek (2) find that when liquids having a surface tension of 0.66 

 or less (pure water being taken as 1 . 00) are applied to plant cells 

 most of the cells are injured and die. The results shown in table III 

 show surface tensions so far above 0.66 that there seems to be no 

 reason whatever for supposing that low surface tension could be a 

 factor in the toxicity of the waters of sphagnum bogs. 



It has been noted in the field by Sherff (10) that rhizomes of 

 Sagittaria are killed when they grow into the decaying portion 

 of the rhizomes of Nymphaea advena. It has also been found by 

 Rigg (loc. cit.) that solutions resulting from the decay of Nymphaea 

 rhizomes are toxic to Tradescantia cuttings and to agricultural 

 plants, even in very dilute solution. 



There is no indication in the data here published that either 

 high osmotic pressure or low surface tension can be a factor of any 

 importance in the toxicity of the solutions resulting from the decay 

 of Nymphaea rhizomes in the extreme dilutions which proved toxic 

 to Tradescantia cuttings and to agricultural plants. 



Summary 



1. The osmotic pressure of bog water in th< 



higher during the rainy season than at the close of the dry season. 



2. The osmotic pressure of the waters tested from lakes and 

 springs was lower during the rainy season than at the close of the 



