﻿BOTANICAL GAZETTE 



the results of all tests made by the writers on such waters: Living- 

 ston's tests on bog waters, 0.009; tests by the writers on bog 

 waters, 0.005; Livingston's tests on other surface waters, 0.007; 

 tests by the writers on other surface waters, 0.003. In so far as 

 the data given can be taken to be representative of the regions, it 

 seems that the osmotic pressure of all waters tested is lower in the 

 region worked in by the writers than in the region in which Living- 

 ston worked. The difference between the average for bog waters 

 and for other surface waters in the two regions is exactly the same. 



Livingston (loc. cit.) found "practically no difference in 

 osmotic pressure corresponding to the season." The average of 

 the determinations made by the writers on bog waters during the 

 rainy season and during the dry season is as follows: rainy season, 

 0.006; dry season, 0.002. Here, as elsewhere in this paper, 

 figures beyond the third place are not considered significant. 



Fitting (4) has concluded that xerophytism and difficulty in 

 absorption do not seem to be correlated with high osmotic pressure 

 (the writers have not seen this paper). 



Whatever conclusions the writers would be justified in drawing 

 from their data would be in substantial agreement with those of 

 Livingston and of Fitting. That is, high osmotic pressure is not 

 the cause of the toxicity of the waters of sphagnum bogs. 



Omitting Crystal Lake (since the properties of its waters seem 

 practically identical with those of bog waters), the comparison of 

 the lowering of the freezing point of lake and spring waters for the 

 wet season and the dry season 3 is as follows: average for the wet 

 season, o . 001 ; average for the dry season, o . 004. This is too small 

 a number of tests to be made the basis of any generalization as to 

 seasonal variation in osmotic pressure in this region. The average 

 of the limited data here cited, however, is just the opposite of the 

 average of the data secured by Transeau (ii) for central Illinois 

 in 1 9 13, when there were no rains of consequence from the middle 

 of April to the middle of September. He found that the highest 

 osmotic pressures were recorded during the spring, when the water 

 levels were highest, and that the lowest records were during the 



